Malicious code in @rbx-ts/services (npm)
The npm package @rbx-ts/services contained obfuscated malicious code in scripts/postinstall.js that downloads and executes a Windows binary from an external file host on npm install. The package was advertised as Roblox TypeScript type definitions but contained no legitimate need for executable payloads.
- Disclosed
- Last updated
- Blast radius
- npm package ecosystem; Windows systems executing npm install
- Ecosystems
- Attack vectors
- Affected entities
- @rbx-ts/servicesnpm package containing malicious postinstall script
The npm package @rbx-ts/services contained malicious code hidden in its postinstall.js script using hex-escaped identifiers and base64-encoded strings to obfuscate standard Node.js API names and a download URL.
Upon npm install on Windows systems (process.platform === 'win32'), the script decodes the base64-encoded URL to https://files.catbox.moe/9bppy2.zip, downloads the archive to the system TEMP directory, expands it using PowerShell's Expand-Archive cmdlet, recursively searches for the first .exe file in the extracted tree, and spawns that binary as a detached process before deleting the archive.
The package was advertised as providing Roblox TypeScript type definitions, which have no legitimate requirement for Windows executable payloads. The attacker used files.catbox.moe, an anonymous throwaway file host that permits mutable content with no version pinning, hash verification, or publisher identity matching.
The incident was identified and credited to the OpenSSF malicious-packages project.
Indicators of compromise
- Packages
- @rbx-ts/services
- Domains
- files.catbox.moe
Remediation
- Immediately uninstall @rbx-ts/services from all systems
- Audit npm install logs and process execution history on Windows systems for suspicious activity
- Scan systems for the presence of first.exe or other executables downloaded from files.catbox.moe
- Review npm audit logs for the affected package version
- Use npm package integrity verification and consider using npm lockfiles with hash verification
- Monitor for similar obfuscated postinstall scripts in dependencies
Sources
- GitHub Advisory GHSA-2846-4m8r-rvv5 · GitHub Advisory Database
Cite this entry
"Malicious code in @rbx-ts/services (npm)." supplychainattack.org, Supply Chain Attack Incident Catalog. Disclosed August 8, 2026; last updated August 8, 2026. https://supplychainattack.org/incident/malicious-code-in-rbx-ts-services-npm-10ccau
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