Malicious code in dolyame-ui-contextmenu (npm)
The npm package dolyame-ui-contextmenu contained malicious code that downloads and executes platform-specific binaries from attacker-controlled Cloudflare Workers subdomains upon installation. The package used obfuscation techniques and covert DNS-TXT channels to evade detection and fetch payloads.
- Disclosed
- Last updated
- Blast radius
- Any developer or application that installed the malicious dolyame-ui-contextmenu package during the compromise window.
- Ecosystems
- Attack vectors
- Affected entities
- dolyame-ui-contextmenunpm package containing malicious code in _polyfill.js
The npm package dolyame-ui-contextmenu was found to contain malicious code in its polyfill.js file. Upon require() of the package, the code downloads platform-specific binaries from hardcoded Cloudflare Workers subdomains (oob-worker.cf99-9b3.workers.dev, oob-worker.cf101-adf.workers.dev, oob-worker.cf102-baf.workers.dev).\n\nThe malicious code writes the downloaded binaries to temporary paths using cover-story names such as 'dotnet_diag.exe' and '.cache_', sets executable permissions (0755), and spawns them detached via cmd.exe (Windows) or /bin/sh (Unix-like systems). The destination hostnames are assembled from array fragments to evade static analysis, and a base64-over-DNS-TXT covert channel under *.dl.wel1.ru is used to fetch payloads when HTTPS is blocked.\n\nThe Cloudflare Workers subdomains are anonymous and unrelated to any documented purpose of the package, and the delivered bytes represent opaque attacker-controlled code executed with the privileges of the installer. This incident was identified by Amazon Inspector and credited to the OpenSSF malicious-packages project.
Indicators of compromise
- Packages
- dolyame-ui-contextmenu
- Domains
- oob-worker.cf99-9b3.workers.dev
- oob-worker.cf101-adf.workers.dev
- oob-worker.cf102-baf.workers.dev
- dl.wel1.ru
Remediation
- Immediately uninstall dolyame-ui-contextmenu from all affected systems and projects
- Audit npm package.lock or yarn.lock files to identify all installations of this package
- Review system logs and process execution history on machines where this package was installed for signs of unauthorized binary execution
- Consider the affected systems as potentially compromised and perform security assessment
- Use npm audit to check for other malicious packages in your dependency tree
- Implement package verification and scanning in your CI/CD pipeline to detect similar threats
Sources
- GitHub Advisory GHSA-chcw-cjqg-q9hq · GitHub Advisory Database
Cite this entry
"Malicious code in dolyame-ui-contextmenu (npm)." supplychainattack.org, Supply Chain Attack Incident Catalog. Disclosed August 7, 2026; last updated August 7, 2026. https://supplychainattack.org/incident/malicious-code-in-dolyame-ui-contextmenu-npm-rrtjkk
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