Malicious code in solidity-testing-utils (npm)
solidity-testing-utils, an npm package masquerading as a Solidity testing helper, contained malicious code that spawned a detached child process to fetch and execute arbitrary code from an attacker-controlled remote JSON storage endpoint. The package used base64-encoded URLs and hardcoded credentials to retrieve and execute payloads with full Node.js require access during installation.
- Disclosed
- Last updated
- Blast radius
- Any npm user who installed solidity-testing-utils
- Ecosystems
- Attack vectors
- Affected entities
- solidity-testing-utilsnpm package
The npm package solidity-testing-utils presented itself as a chai/Solidity testing helper and pino-style logger, but its actual behavior was malicious. When the exported middleware factory in index.js was invoked, it silently spawned a detached child process running lib/caller.js via child_process.spawn() with stdio redirected to /dev/null.
The spawned lib/caller.js process base64-decoded a hardcoded URL pointing to https://api.jsonstorage.net/v1/json/2ef8c758-a96f-459e-b036-b3b90379a165/f89e8264-86c2-4684-94da-c3f82d59370f and performed an HTTP GET request with a hardcoded 'x-secret-key' header. It then extracted the .data.cookie field from the JSON response and passed it to Function.constructor(), granting the fetched payload arbitrary code execution with full require access in the installer's Node.js process.
Because the payload was stored in a mutable attacker-controlled JSON blob, the malicious code could be swapped or updated at any time after installation. The package name and README did not correspond to its actual behavior, making detection difficult for users.
This incident was identified and credited to the OpenSSF's malicious-packages repository.
Indicators of compromise
- Packages
- solidity-testing-utils
- Domains
- api.jsonstorage.net
Remediation
- Immediately uninstall solidity-testing-utils from all environments
- Audit npm install logs and package-lock.json to identify when and where the package was installed
- Assume any system that installed this package may have been compromised; rotate credentials, API keys, and secrets used in those environments
- Review process logs and network traffic from affected systems for signs of unauthorized code execution
- Update to a clean version if a legitimate replacement package is available, or use an alternative testing library
- Implement npm package verification and scanning in CI/CD pipelines to detect malicious packages before installation
Sources
- GitHub Advisory GHSA-g5g4-w6x5-58j4 · GitHub Advisory Database
Cite this entry
"Malicious code in solidity-testing-utils (npm)." supplychainattack.org, Supply Chain Attack Incident Catalog. Disclosed August 23, 2026; last updated August 23, 2026. https://supplychainattack.org/incident/malicious-code-in-solidity-testing-utils-npm-as3jwz
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