Supply chain · npm · High

Critical npm Package 'cc-skills-helper' Delivers Windows-Only Dropper

Threat Engine Auto-Feed · data current as of 2026-08-13

The npm package `cc-skills-helper` version 1.0.0 is a malicious Windows-only supply-chain dropper designed to fetch and execute attacker-controlled native code. It attempts to evade detection and install a Defender exclusion, posing a significant risk to Windows environments where it was installed.

  • Package: npm / cc-skills-helper
  • Affected versions: = 1.0.0
  • Severity: critical
  • Reach: ~454/wk
  • Exposure: 70/100 (High)

What happened — Credential / secret theft

The npm package `cc-skills-helper` version 1.0.0 contains malicious code that, upon installation, acts as a dropper. It fetches a configuration from a hard-coded command-and-control (C2) server, downloads a password-protected ZIP archive containing a Windows executable, decrypts it, and then stages and executes the payload on the victim's system. The package attempts to evade antivirus detection and even instructs users on how to manually add a Defender exclusion.

How the attack works

This attack leverages a malicious software package to deliver a secondary payload. The initial package, when installed, executes a post-installation script. This script connects to an external server to retrieve instructions and a password-protected archive. The archive, containing the final malicious executable, is then downloaded, decrypted, and executed on the host system. The process includes steps to avoid detection by security software and establish persistence or further compromise.

Who's exposed

Profiles most at risk

  • Organizations and development teams using npm in Windows environments
  • Developers who installed `cc-skills-helper` version 1.0.0 directly or as a dependency
  • CI/CD pipelines running on Windows that pulled `cc-skills-helper` version 1.0.0

Conditions that increase exposure

  • Unpinned dependencies that allowed `cc-skills-helper` version 1.0.0 to be installed
  • Lack of lockfiles (e.g., `package-lock.json`) in projects
  • Running `npm install` from an elevated shell on Windows, which could allow Defender exclusions
  • Systems that installed the package between 2026-04-25 and the C2 neutralization

Blast-radius scenarios

  • An attacker gains remote code execution on Windows systems where the package was installed.
  • The attacker can deliver various payloads, as the C2 can serve different executables.
  • Compromised systems may have security software exclusions, making further detection difficult.

What to do (defensive)

Detect

  • Scan Windows systems for the presence of `cc-skills-helper` executable under `%LOCALAPPDATA%\cc-skills-helper\bin\helper-<8-hex>.exe`.
  • Review npm project dependencies for `cc-skills-helper` version 1.0.0.
  • Monitor network traffic for connections to `https://kiro-cheap.pro/api/config` or other suspicious external domains from build environments or developer machines.
  • Check Windows Defender exclusion lists for `%LOCALAPPDATA%\cc-skills-helper`.

Contain

  • Immediately quarantine or isolate any Windows systems identified with the `cc-skills-helper` package installed.
  • Block network access to `https://kiro-cheap.pro` at the perimeter.
  • Remove `cc-skills-helper` from all `package.json` files and dependency trees.
  • Review and update dependency pinning strategies to prevent installation of unvetted packages.

Remediate

  • Remove `cc-skills-helper` from all affected projects and rebuild applications with clean dependencies.
  • Perform a full forensic analysis on any Windows system that installed `cc-skills-helper` version 1.0.0 to identify the extent of compromise.
  • Reset credentials and secrets on any system that installed the package, especially if those systems had access to sensitive data.
  • Ensure Windows Defender exclusions are reviewed and any suspicious exclusions related to `cc-skills-helper` are removed.

Frontier verdict — High

Prioritize immediate detection and removal of `cc-skills-helper` due to its critical severity as a Windows-only supply-chain dropper with evasion capabilities.

Sources

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