stubsoutPyPI
Advisory published Updated
stubsout is a confirmed malicious PyPI package (MAL-2025-191879) that steals credentials and exfiltrates sensitive data (malicious versions 0.0.1, 0.0.2). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in stubsout (PyPI)
What this malware does
While described as telemetry, importing the package attempts to send out some basic info as well as quite sensitive environmental variables.
Category: MALICIOUS - The campaign has clearly malicious intent, like infostealers.
Campaign: 2025-06-stubsout
Reasons (based on the campaign):
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The package contains code to exfiltrate basic data from the system, like IP or username. It has a limited risk.
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exfiltration-env-variables
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Credential / info stealerFind it
Search your lockfiles and build artifacts for stubsout (2 malicious versions).
If you installed it — respond
stubsout is built to steal secrets, so assume every credential the build or runtime could read is compromised. Remove it from your project and lockfile, then rotate ALL exposed secrets — npm/registry tokens, cloud keys, CI/CD secrets, SSH keys, and any .env values — from a known-clean machine. Audit logs for unauthorized use of those credentials.
Did it already run?
If stubsout was installed, its post-install payload may already have run. Removing the package does not undo that — check outbound connections and credential use from the install window onward.
Frequently asked questions
Campaign
References
Credits
- Kamil Mańkowski (kam193)
Detect & block this
O3 blocks stubsout-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.