MAL-2026-17604 Malicious code in keccka (RubyGems)

RubyGems runs this gem's native extension script ext/keccka/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.

The gem's native extension is a cover: ext/keccka/keccka.c is an empty stub and extconf.rb — auto-executed by gem install — contains a base64-wrapped Ruby payload decoded and passed to eval. The payload XOR-decodes a hardcoded C2 URL (http://45.138.12.177:8092/wgkit.tar.gz), curls the tarball over plain HTTP to a bare IP, and runs bash /tmp/.w1/wg_install.sh from the extracted content. Execution is gated by anti-analysis checks: it skips when CI environment variables are set (CI, GITHUB_ACTIONS, TRAVIS, JENKINS_URL, GITLAB_CI, CODESPACES), when the hostname matches ephemeral/sandbox patterns (firecracker, sandbox, vagrant), when the username looks generated (sandbox, tester, analys, scanner, uA\d+), when the working directory is an analysis path (/tmp, /opt/rubygems, /workspace), or when system uptime is under 1800 seconds, and it requires developer-looking signals on disk (~/.ssh, ~/.gitconfig, ~/.gem/credentials). On a matching host it double-forks a detached child that sleeps 20-40 minutes before fetching and executing. The destination is a plaintext, unauthenticated bare-IP host unrelated to any legitimate publisher; the fetched shell script is unpinned, unverified, and attacker-controlled.

The OpenSSF Package Analysis project identified 'keccka' @ 1.0.0 (rubygems) as malicious.

It is considered malicious because:

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