GCVE-110-OSM-2026-3259

Backdoors the victim machine at install time by spawning a persistent GitHub-backed C2 agent: postinstall launches a detached background process that decrypts an embedded GitHub PAT, establishes an RSA-2048 key exchange with the attacker via sbaby1997/openaisdk, and polls for encrypted commands every 5 seconds — executing arbitrary shell commands via child_process.exec and exfiltrating results (and arbitrary file contents) back to the C2 repository with RSA-2048+AES-256-GCM encryption. User-agent 'c2-poc' in source confirms intentional C2 design; the C2 repository is now deleted (ephemeral infrastructure). 235 downloads/week at time of detection. **Trigger** (postinstall): postinstall.js checks platform===darwin, then spawns `node client.js -key githubkey@123` with {detached:true}.unref() — the C2 agent survives npm exit. **Key exchange**: client.js decrypts ENCRYPTED_GITHUB_TOKEN (AES-256-GCM, passphrase 'githubkey@123', salt 'c2-github-token-kdf-v1') and POSTs freshly generated RSA-2048 public key + client_boot_id to handshake.json in sbaby1997/openaisdk. **Command loop**: Polls `https://api.github.com/repos/sbaby1997/openaisdk/contents/cmd.json` every 5 seconds. Supports type=shell (child_process.exec of arbitrary command), type=upload (fs.promises.readFile + exfil), type=write (fs.promises.writeFile on victim). **Exfiltration**: Output encrypted with server RSA-2048 public key (OAEP/SHA-256 + AES-256-GCM), written to `https://api.github.com/repos/sbaby1997/openaisdk/contents/data.json` via GitHub Contents API PUT.