GHSA-955r-262c-33jc: 
Python vulnerability analysis and mitigation

Summary

On March 27, 2026, a threat actor used compromised PyPI credentials to publish malicious versions 4.87.1 and 4.87.2 of the telnyx Python package directly to PyPI. These versions contain credential-stealing malware and were not published through the legitimate GitHub release pipeline.

Exposure Window

Both versions were quarantined by PyPI at 2026-03-27 10:13 UTC. Note: Version 4.87.1 contained a typo that prevented the malware from executing. Only 4.87.2 was fully functional.

Who Is Affected

You may be affected if:

• You installed or upgraded the telnyx Python package between 03:51 UTC and 10:13 UTC on March 27, 2026
• You ran pip install telnyx without pinning a version and received 4.87.1 or 4.87.2
• A dependency in your project pulled in telnyx as a transitive, unpinned dependencyYou are NOT affected if:
• You pinned to version 4.87.0 or earlier
• You installed before March 27, 2026 and did not upgrade
• You built from GitHub source (malicious code was never committed to the repository)

Attack Details

Root Cause

The attacker obtained the PyPI API token and uploaded malicious packages directly to PyPI, bypassing the GitHub release pipeline entirely. No malicious commits exist in the GitHub repository.

Malicious Behavior

The malware is injected into telnyx/_client.py (74 additional lines) and executes on import telnyx: Linux/macOS:

1. Spawns detached subprocess to survive parent exit
2. Downloads payload hidden inside WAV audio file (steganography) from C2
3. Harvests credentials: SSH keys, AWS/GCP/Azure creds, Kubernetes tokens, Docker configs, .env files, database credentials, crypto wallets
4. If Kubernetes access found, deploys privileged pods to all nodes for lateral movement
5. Encrypts with AES-256-CBC + RSA-4096, exfiltrates to C2

Windows:

1. Downloads binary hidden inside WAV file from C2
2. Drops as msbuild.exe in Startup folder for persistence
3. Executes with hidden window

Version Differences

Verified Safe Version

Recommended Actions

1. Check If You Are Affected

# Check installed version
pip show telnyx | grep Version

# Check pip cache for telnyx versions
pip cache list telnyx 2>/dev/null

# Check when telnyx was installed (modification time)
ls -la $(python -c "import site; print(site.getsitepackages()[0])")/telnyx* 2>/dev/null

2. Remove Compromised Versions

pip uninstall telnyx

3. Rotate All Potentially Exposed Secrets

If there is any possibility that version 4.87.1 or 4.87.2 was installed in your environment, treat all accessible secrets as compromised:

• SSH keys
• AWS/GCP/Azure credentials
• Kubernetes tokens and service accounts
• Docker registry credentials
• Database passwords
• API keys in .env files
• Telnyx API keys

4. Check for Persistence (Linux/macOS)

# Check for malicious systemd service
systemctl --user status audiomon 2>/dev/null
ls -la ~/.config/audiomon/ 2>/dev/null

# Check state file
ls -la /tmp/.initd_state 2>/dev/null

5. Check for Persistence (Windows)

# Check Startup folder
Get-ChildItem "$env:APPDATA\Microsoft\Windows\Start Menu\Programs\Startup\msbuild.exe"

6. Pin to Safe Version

pip install telnyx==4.87.0

Or in requirements.txt:

telnyx==4.87.0

Indicators of Compromise

Malicious Package Hashes

Network

Filesystem

Exfiltration

• Archive name: tpcp.tar.gz
• HTTP header: X-Filename: tpcp.tar.gz
• Encryption: AES-256-CBC + RSA-4096 OAEP

Attribution

This attack is attributed to TeamPCP with high confidence based on:

• Identical RSA-4096 public key as the LiteLLM compromise (March 24, 2026)
• tpcp.tar.gz archive naming convention (TeamPCP signature)
• Identical AES-256-CBC + RSA OAEP encryption scheme
• Same credential harvesting targets and techniquesRSA Key Hash:
• PEM SHA-256: 4eceb569b4330565b93058465beab0e6d5ea09cfba8e7f29d7be1b5a2abd958a

Resources

• https://github.com/team-telnyx/telnyx-python/issues/235
• https://www.endorlabs.com/learn/teampcp-strikes-again-telnyx-compromised-three-days-after-litellm
• https://ramimac.me/teampcp