{"id":"MAL-2026-17582","summary":"Malicious code in bitciin (RubyGems)","details":"RubyGems runs this gem's native extension script `ext/bitciin/extconf.rb` during `gem install`. The script exits without action on CI runners and sandboxes, based on CI environment variables, the hostname, the username and the working directory. It continues if the system uptime is over 30 minutes and the home directory holds `.ssh`, `.gitconfig`, `.npmrc`, `.gem/credentials` or `.bundle`. It then decodes a Base64 Ruby payload and forks twice into a detached process. After 20 to 40 minutes the payload downloads `http://45.138.12.177:8092/wgkit.tar.gz` to `/tmp/.w1.tgz` with `curl`, extracts it to `/tmp/.w1/`, runs `wg_install.sh` with `bash` and deletes both. The payload stores the URL XOR-encoded with the key `usv\\x9a`. The Ruby code in `lib/` is a decoy. The RubyGems account `reqthrottle_3474` published this gem and 41 others with the same loader on 2026-10-05.\n\n---\n_-= Per source details. Do not edit below this line.=-_\n\n## Source: amazon-inspector (73144cb471499af4467e7c8c2a6da34013285179444e101290faa7ec9fda0a19)\nThe gem declares a native extension (ext/bitciin/extconf.rb) that runs during `gem install`. The shipped C source (ext/bitciin/bitciin.c) is a two-line empty stub (`void Init_Bitciin(void) {}`) and the Ruby library exposes only a static wordlist helper, so the native-extension declaration exists purely to trigger extconf.rb. extconf.rb applies a sandbox-evasion gate (checks for CI environment variables, hostname/username/cwd regexes, uptime \u003e 1800s, and presence of ~/.ssh, ~/.gitconfig, ~/.gem/credentials, ~/.bundle, and ~/.npmrc as a developer-machine signal) and, when the gate passes, double-forks and evals a base64-wrapped Ruby payload. The payload reconstructs a C2 URL by XORing a hex blob with the 4-byte key `usv\\x9a` (with env-var override WG_KIT_URL), sleeps 20-40 minutes, then curls a tarball to /tmp/.w1.tgz and executes bash /tmp/.w1/wg_install.sh. The installer-secret paths probed by the gate specifically include publisher-credential locations (~/.gem/credentials, ~/.npmrc), consistent with a credential-targeted stage-2.\n","modified":"2026-10-05T23:45:03.564877423Z","published":"2026-10-05T09:30:00Z","database_specific":{"malicious-packages-origins":[{"import_time":"2026-10-05T16:22:55.428472327Z","modified_time":"2026-10-05T15:58:03Z","sha256":"73144cb471499af4467e7c8c2a6da34013285179444e101290faa7ec9fda0a19","source":"amazon-inspector","versions":["1.0.0"],"id":"IN-MAL-2026-021058"}],"iocs":{"urls":["http://45.138.12.177:8092/wgkit.tar.gz"],"files":[{"source":"PACKAGE_ARCHIVE","digests":{"sha256":"977d0764ae375bd6a338c2dd9a3e55ea732a20b19fb9b0ec035171bb8f39f68e"},"note":"Native extension script that RubyGems runs at install time. It gates on the environment and starts the payload.","paths":["ext/bitciin/extconf.rb"]},{"note":"Second-stage archive and install script downloaded and run by the payload.","paths":["/tmp/.w1.tgz","/tmp/.w1/wg_install.sh"],"source":"DROPPED"}],"ips":["45.138.12.177"]}},"references":[{"type":"PACKAGE","url":"https://rubygems.org/gems/bitciin/versions/1.0.0"},{"type":"REPORT","url":"https://safedep.io/rubygems-crypto-gems-install-time-reverse-shell/"}],"affected":[{"package":{"name":"bitciin","ecosystem":"RubyGems","purl":"pkg:gem/bitciin"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.0.0"],"database_specific":{"source":"https://github.com/ossf/malicious-packages/blob/main/osv/malicious/rubygems/bitciin/MAL-2026-17582.json","cwes":[{"cweId":"CWE-506","description":"The product contains code that appears to be malicious in nature.","name":"Embedded Malicious Code"},{"name":"Embedded Malicious Code","cweId":"CWE-506","description":"The product contains code that appears to be malicious in nature."}],"indicators":{"evidence_files":[{"path":"ext/bitciin/extconf.rb","sha256":"977d0764ae375bd6a338c2dd9a3e55ea732a20b19fb9b0ec035171bb8f39f68e","tlsh":"6851db568b8395f54db1d0d044355412fb667b0d6068ac64f3de086cbb5af2ac4f02fd"},{"path":"ext/bitciin/bitciin.c","sha256":"3ea6f0ef00d7fe7e8436de537736458949461e26f1cc4904956a49d523a9351a"}]}}}],"schema_version":"1.9.0","credits":[{"name":"Amazon Inspector","contact":["inspector-research@amazon.com"],"type":"FINDER"},{"name":"SafeDep","contact":["https://safedep.io"],"type":"FINDER"}]}