Which versions of ultrafasttelethon are malicious?

The following PyPI versions of ultrafasttelethon are flagged malicious: 1.39.0, 1.39.0.1, 1.39.0.2, 1.39.0.3. Treat any of these as compromised.

How do I remediate ultrafasttelethon if I installed it?

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

If ultrafasttelethon 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 ultrafasttelethon part of a known attack campaign?

Yes — ultrafasttelethon is associated with the 2025-04-fastgram 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 ultrafasttelethon across my projects, lockfiles, and CI pipelines?

Search your lockfiles and build artifacts for ultrafasttelethon (4 malicious versions).

Malicious package

ultrafasttelethonPyPI

Advisory published Apr 4, 2025Updated Dec 12, 2025

ultrafasttelethon is a confirmed malicious PyPI package (MAL-2025-191915) that steals credentials and exfiltrates sensitive data (malicious versions 1.39.0, 1.39.0.1, 1.39.0.2…). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in ultrafasttelethon (PyPI)

MAL-2025-191915

Immediate action

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

pip uninstall ultrafasttelethon

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

4 flagged

1.39.01.39.0.11.39.0.21.39.0.3

Indicators of compromise (SHA-256)

2f2335d63eb797b5edb8c95d3c5c088e72acab99487bbea8294706207e379ad0

73a960b0cd2d21f8bde61f22f956a4c2a02ccddd9e1277eef23d3d8e0406cba4

29602e2cd7f36a4d478bdcd0bb75c12f7c61a35d253b73bd36f9a1e6975adab2

Detection & response playbook

Credential / info stealer

Find it
Search your lockfiles and build artifacts for ultrafasttelethon (4 malicious versions).
If you installed it — respond
ultrafasttelethon 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 ultrafasttelethon 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. ultrafasttelethon on PyPI has been identified as a malicious package (versions 1.39.0, 1.39.0.1, 1.39.0.2, 1.39.0.3 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

2025-04-fastgram

References

bad-packages.kam193.eu

Credits

Kamil Mańkowski (kam193)

Detect & block this

O3 blocks ultrafasttelethon-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

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