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Malicious package

fastertelethonPyPI

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

MAL-2025-191723
Immediate action
Remove the package, then rotate any secrets the build/runtime could reach.
pip uninstall fastertelethon

What this malware does

Clone of Telethon package that exfiltrates credentials. See client/telegrambaseclient.py L608-626 (exfiltration function) and client/auth.py L163 (usage).

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

Campaign: 2025-04-fastgram

Reasons (based on the campaign):

  • clones-real-package

  • action-hidden-in-lib-usage

  • exfiltration-generic

Malicious versions

2 flagged
1.0.01.0.5

Indicators of compromise (SHA-256)

b24babfe443100b225270a7cc7bff07ed10e39121be0694653ec59a91ef88a3b
3ccfc281c2541df7e1354e6de8c64624fdc75dcc229d33962b171b0a95087edf
ca8244ca6a84b757f58716bc8bb3a219e381ba136bb9c637d29fc549f928cef6
8ab64081fd1ef60d3b7ca9424cbe8653e1b3716d9fc8bb721919501ccef08714

Detection & response playbook

Credential / info stealer
  1. Find it

    Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for fastertelethon (2 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging fastertelethon across your stack and pipelines.

  2. If you installed it — respond

    fastertelethon 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.

  3. Did it already run?

    If fastertelethon 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 fastertelethon 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. fastertelethon on PyPI has been identified as a malicious package (versions 1.0.0, 1.0.5 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

2025-04-fastgram

References

Credits

  • Kamil Mańkowski (kam193)

Detect & block this

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

fastertelethon (PyPI) malicious package — MAL-2025-191723 | O3 Security