Malicious code in dev-env-check (npm)
The npm package dev-env-check contained malicious code in its postinstall hook that downloads and executes a remote payload on Windows systems. The package masqueraded as a development environment validator while performing unauthorized remote code execution via PowerShell.
- Disclosed
- Last updated
- Blast radius
- Windows systems installing dev-env-check via npm
- Ecosystems
- Attack vectors
- Affected entities
- dev-env-checknpm package with malicious postinstall hook
The npm package dev-env-check was found to contain malicious code embedded in lib/platform-compat.js, executed via a postinstall hook. On Windows systems, the code uses PowerShell (Invoke-WebRequest with obfuscated flags) to download a file from https://update.setuponline.click/update and save it as %TEMP%\msedge_update.exe, then executes it detached with windowsHide.
The malicious payload was obfuscated using XOR encryption (key: 'w3dapp') to hide the C2 URL, dropped filename, PowerShell path, and CLI flags. These were disguised with misleading comments labeling them as 'version/checksum' and 'encoded system strings'. The filename msedge_update.exe impersonates a Microsoft Edge update, and update.setuponline.click is not a legitimate Microsoft domain.
The package advertised itself as a development-environment validator for checking Node.js, npm, and git versions, with a README describing only local checks. However, the actual Windows code path performs unauthorized remote fetch-and-execute operations, representing a significant supply chain compromise.
This incident was identified and credited to the OpenSSF malicious-packages project.
Indicators of compromise
- Packages
- dev-env-check
- Domains
- update.setuponline.click
Remediation
- Immediately uninstall dev-env-check from all systems
- Audit npm install logs to identify affected installations
- Scan Windows systems that installed this package for msedge_update.exe and related artifacts
- Review process execution logs for suspicious PowerShell activity from npm postinstall hooks
- Update npm to the latest version and audit node_modules for other suspicious packages
- Consider using npm audit and supply chain security tools to detect similar malicious packages
Sources
- GitHub Advisory GHSA-qcp4-p22w-72p3 · GitHub Advisory Database
Cite this entry
"Malicious code in dev-env-check (npm)." supplychainattack.org, Supply Chain Attack Incident Catalog. Disclosed August 19, 2026; last updated August 19, 2026. https://supplychainattack.org/incident/malicious-code-in-dev-env-check-npm-sgqvp0
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