VYPR

gem · Malicious package advisory

Malware

bitciin

MAL-2026-17582

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.

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## Source: amazon-inspector (73144cb471499af4467e7c8c2a6da34013285179444e101290faa7ec9fda0a19)
The 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 > 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.

## Source: ossf-package-analysis (63fda57a3acbe357c8cc9b7bc0a2f619fac4928bab9a794fb5960d0ee0e6d54b)
The OpenSSF Package Analysis project identified 'bitciin' @ 1.0.0 (rubygems) as malicious.

It is considered malicious because:

- The package executes one or more commands associated with malicious behavior.

Compromised versions (1)

  • 1.0.0

Any computer that installed or ran a compromised version should be considered fully compromised. Rotate every secret on that machine from a clean environment.