Which versions of crc32fast are malicious?

The following PyPI versions of crc32fast are flagged malicious: 1.0.99. Treat any of these as compromised.

How do I remediate crc32fast if I installed it?

crc32fast 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.

I already installed crc32fast — how do I know if it already compromised me?

If crc32fast 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.

Is crc32fast part of a known attack campaign?

Yes — crc32fast is associated with the GENERIC-standard-pypi-install-pentest campaign. Packages in the same campaign often share infrastructure and payloads, so check whether any related packages are also in your dependency tree.

How do I find crc32fast across my projects, lockfiles, and CI pipelines?

Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for crc32fast (version 1.0.99). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging crc32fast across your stack and pipelines.

Malicious package

crc32fastPyPI

Malicious code in crc32fast (PyPI) Remove it immediately and rotate any exposed credentials.

MAL-2026-902

Immediate action

Remove the package, then rotate any secrets the build/runtime could reach.

pip uninstall crc32fast

What this malware does

Installing the package or importing the module exfiltrates basic information about the host, and the package has no other purpose.

Category: PROBABLY_PENTEST - Packages looking like typical pentest packages, but also anything that looks like testing, exploring pre-prepared kits, research & co, with clearly low-harm possibilities.

Campaign: GENERIC-standard-pypi-install-pentest

Reasons (based on the campaign):

The package contains code to exfiltrate basic data from the system, like IP or username. It has a limited risk.
The package overrides the install command in setup.py to execute malicious code during installation.

The OpenSSF Package Analysis project identified 'crc32fast' @ 1.0.99 (pypi) as malicious.

It is considered malicious because:

The package communicates with a domain associated with malicious activity.
The package executes one or more commands associated with malicious behavior.

Malicious versions

1 flagged

1.0.99

Indicators of compromise (SHA-256)

01c9a259f7b88e992aee84db09b728b15f74a517857ab5b3aaa16f725a9debbd

3b89c674974bf58c7388a27bf1c6ea954a890de45a3e9ba4830c1eada3a3ea6a

Detection & response playbook

Credential / info stealer

Find it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for crc32fast (version 1.0.99). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging crc32fast across your stack and pipelines.
If you installed it — respond
crc32fast 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 crc32fast 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.
How O3 protects you
O3 blocks crc32fast 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. crc32fast on PyPI has been identified as a malicious package (version 1.0.99 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

GENERIC-standard-pypi-install-pentest

References

bad-packages.kam193.eu

Credits

Kamil Mańkowski (kam193) · reporter
OpenSSF: Package Analysis · finder

Detect & block this

O3 blocks crc32fast-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.

Malware detection Runtime egress monitoring