Critical Vulnerability in @posthog/filter-out-plugin: Malicious Code Injection
Summary
MAL-2025-191290: Malicious code in @posthog/filter-out-plugin (npm). Affects @posthog/filter-out-plugin versions 0.0.8. No fix is published. How to fix ↓
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Background
The @posthog/filter-out-plugin is an npm package designed to enhance data filtering capabilities within PostHog, a product analytics tool. This package allows users to customize and filter analytics data effectively. However, it has recently been compromised, exposing users to significant security risks due to malicious code embedded in the package.
Vulnerability Detail
The vulnerability stems from a compromise by the Sha1-Hulud: The Second Coming NPM worm, which has infected the @posthog/filter-out-plugin package. This malicious payload is designed to steal sensitive tokens and credentials from users and publish them to GitHub. Additionally, the worm can propagate itself to other NPM packages owned by the user and establish persistence through GitHub actions. There is also a risk that the worm may destroy the user's home directory, leading to potential data loss.
How To Fix
This package is malicious. Remove it and rotate any credentials it could have accessed.
npm uninstall @posthog/filter-out-pluginIf it arrived as a transitive dependency, remove the package that pulled it in, then reinstall.
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Workaround
As a temporary workaround, users should consider removing the @posthog/filter-out-plugin package from their project until a secure version is released. This can be done using the following command: npm uninstall @posthog/filter-out-plugin. Additionally, monitor your system for any unauthorized access or changes.
Conclusion
The @posthog/filter-out-plugin has been compromised by a malicious NPM worm, posing serious security risks to users. Immediate action is required to update or remove the package to protect sensitive data and maintain system integrity. Utilizing tools like Vulert can help monitor for such vulnerabilities in the future.
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FAQ
The malicious code is designed to steal sensitive tokens and credentials, potentially leading to unauthorized access to user accounts.
You can use Vulert, which monitors and alerts for open-source vulnerabilities in real-time. Visit Vulert Scanner to check if your application is affected without any signup.
If you have installed the compromised package, you should uninstall it immediately and monitor your system for any signs of unauthorized access.
Regularly update your dependencies, use tools like Vulert to monitor vulnerabilities, and review package sources before installation to mitigate risks.
Failure to address this vulnerability could lead to data breaches, loss of sensitive information, and unauthorized access to your systems.
