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Malicious package

zlib1g-devPyPI

Malicious code in zlib1g-dev (PyPI) Remove it immediately and rotate any exposed credentials.

MAL-2025-41804
Immediate action
Remove the package, then rotate any secrets the build/runtime could reach.
pip uninstall zlib1g-dev

Malicious versions

1 flagged
99.99.99

Indicators of compromise (SHA-256)

596e416d52cf2672fafc3d006ded7573bb839370bdec71701ec85c9e466e9adc

Detection & response playbook

Malicious package
  1. Find it

    Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for zlib1g-dev (version 99.99.99). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging zlib1g-dev across your stack and pipelines.

  2. If you installed it — respond

    Remove zlib1g-dev from your project and lockfile, then assume any secrets accessible to the build or runtime were exposed: rotate API keys, tokens, and credentials, and audit for unexpected outbound activity or persistence.

  3. Did it already run?

    If zlib1g-dev was ever installed, its post-install/runtime payload may have already executed. O3's L7 egress monitoring and runtime eBPF sensors detect the credential exfiltration or command-and-control callback after install and block the malicious outbound channel, so you catch and contain the actual compromise — not just the presence of the package.

  4. How O3 protects you

    O3 blocks zlib1g-dev before install through its supply-chain scanner, and if it has already run, detects and severs the exfiltration or C2 callback at runtime through L7 egress monitoring and eBPF.

Frequently asked questions

No. zlib1g-dev on PyPI has been identified as a malicious package (version 99.99.99 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

RLMA-2025-04302

Credits

  • ReversingLabs · finder

Detect & block this

O3 blocks zlib1g-dev-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the malicious outbound activity and severs the channel.

zlib1g-dev (PyPI) malicious package — MAL-2025-41804 | O3 Security