Malicious Code Injection in my-ctf-helper-script-9921: Exposing User Cookies
Summary
MAL-2026-16365: Malicious code in my-ctf-helper-script-9921 (npm). Affects my-ctf-helper-script-9921 versions 1.0.0. No fix is published. How to fix ↓
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Background
The package 'my-ctf-helper-script-9921' is an npm module designed for use in Capture The Flag (CTF) competitions. It is intended to assist users in managing various tasks related to CTF challenges. However, this package has been found to contain malicious code that executes upon import, compromising user security by sending sensitive cookie data to an external server.
Vulnerability Detail
The vulnerability originates from the package's main module, which executes a top-level fetch to a hardcoded URL (https://webhook.site/99e9df7b-fe86-4c60-822a-5352b1f9edf0/) when required or imported. This fetch appends the document.cookie as a query-string parameter, effectively leaking the user's cookies to a third-party webhook endpoint controlled by malicious actors. The implications of this vulnerability are severe, as it can lead to unauthorized access to user sessions and sensitive information.
How To Fix
This package is malicious. Remove it and rotate any credentials it could have accessed.
npm uninstall my-ctf-helper-script-9921If it arrived as a transitive dependency, remove the package that pulled it in, then reinstall.
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Workaround
As a temporary measure, you can avoid using the 'my-ctf-helper-script-9921' package altogether until a secure version is released. Additionally, consider using alternative packages that provide similar functionality without the risk of malicious code.
Conclusion
The 'my-ctf-helper-script-9921' package contains a serious vulnerability that exposes user cookies to malicious actors. Immediate action is required to remove the package and safeguard user data. Regular monitoring and updates are essential to maintain application security.
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FAQ
The vulnerability allows the package to send user cookies to a malicious third-party server, potentially compromising user sessions.
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Remove the package from your project immediately and monitor for any updates or patches that may be released.
As of now, there is no safe version available. It is best to avoid using this package until a patched version is released.
Regularly audit your dependencies for vulnerabilities, use tools like Vulert to monitor your packages, and keep your libraries up to date.
