Which versions of fernets are malicious?

The following PyPI versions of fernets are flagged malicious: 0.0.1. Treat any of these as compromised.

How do I remediate fernets if I installed it?

fernets 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 fernets — how do I know if it already compromised me?

If fernets 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.

Is fernets part of a known attack campaign?

Yes — fernets is associated with the 2025-05-fernets 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 fernets across my projects, lockfiles, and CI pipelines?

Search your lockfiles and build artifacts for fernets (version 0.0.1).

Malicious package

fernetsPyPI

Advisory published May 27, 2025Updated Dec 12, 2025

fernets is a confirmed malicious PyPI package (MAL-2025-191728) that steals credentials and exfiltrates sensitive data (malicious version 0.0.1). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in fernets (PyPI)

MAL-2025-191728

Immediate action

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

pip uninstall fernets

What this malware does

If imported, the module starts a multi-stage infostealer, exfiltrating browser data as well as crypto wallets, and also attempts to monitor clipboard looking for crypto wallets addresses

Category: MALICIOUS - The campaign has clearly malicious intent, like infostealers.

Campaign: 2025-05-fernets

Reasons (based on the campaign):

infostealer
clipboard-stealing
exfiltration-generic
obfuscation
exfiltration-browser-data
exfiltration-crypto
typosquatting

Malicious versions

1 flagged

0.0.1

Indicators of compromise (SHA-256)

dd3b7424b135987d6afd4a7db4a598da28ae35e6bb3f23479895719e7259167e

95fc75ed8a4cfcccc988b2241772effbc15eb3700a6a96f3183981a1b4c7fba7

33de23a7d91f271bac26de71646bc5fa1929e08997ce7ef81d5bdc0bbc45f0d6

Detection & response playbook

Credential / info stealer

Find it
Search your lockfiles and build artifacts for fernets (version 0.0.1).
If you installed it — respond
fernets 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 fernets 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

No. fernets on PyPI has been identified as a malicious package (version 0.0.1 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

2025-05-fernets

References

bad-packages.kam193.eu

Credits

Kamil Mańkowski (kam193)

Detect & block this

O3 blocks fernets-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

Explore

All malware advisories How O3 detects malware Vulnerability database