Supply chain · pip · High

Malicious pip package 'urc' exfiltrates host data upon installation

Threat Engine Auto-Feed · data current as of 2026-09-19

The 'urc' package (version 99.99.99) in the PyPI ecosystem contains malicious code designed to exfiltrate basic host information. Installation of this package or importing its module triggers the data exfiltration, posing a supply-chain risk to Python development environments.

  • Package: pip / urc
  • Affected versions: = 99.99.99
  • Severity: critical
  • Reach: unknown
  • Exposure: 65/100 (High)

What happened — Credential / secret theft

A malicious package named 'urc' (version 99.99.99) was published to PyPI. This package's primary function is to exfiltrate basic information about the host system upon installation or module import. It achieves this by overriding the install command in `setup.py` to execute malicious code during the installation process.

How the attack works

This is a software supply-chain attack where a malicious package is introduced into a public registry. When developers or automated systems install this package, the embedded malicious code executes. In this specific case, the code is designed to collect and transmit basic system data, such as IP address or username, to an external location.

Who's exposed

Profiles most at risk

  • Development teams using Python and PyPI
  • CI/CD pipelines that pull dependencies from PyPI
  • Organizations with internal package mirrors that sync from PyPI

Conditions that increase exposure

  • Projects with unpinned dependencies that might inadvertently pull the malicious version
  • Environments lacking `requirements.txt` or `Pipfile.lock` to ensure deterministic dependency resolution
  • Automated build systems that install packages without strict version constraints
  • Developers who manually install packages without prior vetting

Blast-radius scenarios

  • An attacker gains basic reconnaissance data about the compromised host, including IP address and username, which can be used for further targeted attacks.
  • The installation of this package could serve as an initial foothold for more sophisticated attacks, even if the immediate data exfiltration is limited.
  • Compromised build environments could lead to tainted artifacts being deployed downstream.

What to do (defensive)

Detect

  • Scan `requirements.txt` and `Pipfile.lock` for `urc==99.99.99`.
  • Monitor network traffic for unusual outbound connections from build systems or development machines after package installations.
  • Review `setup.py` files of newly introduced or updated packages for suspicious `install` command overrides.

Contain

  • Immediately quarantine any systems or build environments found to have installed `urc==99.99.99`.
  • Block `urc` version `99.99.99` at your network perimeter or internal package proxy/mirror.
  • Revoke any credentials that may have been present on compromised systems during the package installation.

Remediate

  • Remove `urc==99.99.99` from all project dependencies.
  • Rebuild affected applications and environments with clean dependencies.
  • Implement strict dependency version pinning (e.g., using `requirements.txt` with exact versions or lock files) to prevent similar incidents.
  • Educate developers on vetting new packages and understanding the risks of supply-chain attacks.

Frontier verdict — High

Prioritize immediate detection and removal of 'urc' version 99.99.99 due to its critical severity and host data exfiltration capabilities.

Sources

For detection-engineering and awareness only · point-in-time · not security advice · sourced from the GitHub Advisory Database.