MAL-2026-17610 Malicious code in solaan-ruby (RubyGems)

RubyGems runs this gem's native extension script ext/solaan-ruby/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 build script (extconf.rb) carries a base64-encoded Ruby payload that executes at gem install time via the standard mkmf build hook. The accompanying C source is a 2-line empty stub, so building a native extension is not the real purpose of the file — the gem exists to run the embedded payload. The payload XOR-reconstructs a URL pointing at the hardcoded bare-IP endpoint http://45.138.12.177:8092/wgkit.tar.gz, curls the tarball to /tmp/.w1.tgz with no integrity check, extracts it to /tmp/.w1, and runs bash /tmp/.w1/wg_install.sh, giving the operator of that IP arbitrary code execution on the installer's host. Execution is gated by evasion checks that abort on CI environments, hostnames matching uvm/firecracker/sandbox/vagrant, usernames matching scanner patterns, working directories under /tmp or /opt/rubygems, and /proc/uptime under 1800 seconds, and only proceeds when developer artifacts are present on disk (~/.ssh, ~/.gitconfig, ~/.gem/credentials, ~/.bundle). The dropper additionally forks a detached child and sleeps a randomized 20–40 minutes before the fetch to evade install-time observation. The combination of obfuscated remote URL, bare-IP HTTP source, pipe-to-bash execution, sandbox evasion, and developer-workstation targeting is an install-time remote code execution attack against developer machines that install the gem.

The OpenSSF Package Analysis project identified 'solaan-ruby' @ 1.0.0 (rubygems) as malicious.

It is considered malicious because:

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