web3-sign-helperRubyGems

RubyGems runs this gem's native extension script ext/web3-sign-helper/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 declares a C native extension at ext/web3-sign-helper/extconf.rb, but the shipped C source is a 53-byte empty Init_Web3SignHelper stub and the Ruby library only exposes a static word list — the native-extension declaration exists solely to get extconf.rb executed by RubyGems at install time. Before create_makefile, extconf.rb evaluates a base64-decoded Ruby payload that reconstructs a download URL by XORing a hardcoded hex blob against the key "usv\x9a" (overridable via the WG_KIT_URL environment variable), sleeps for a randomized 20-40 minute delay, curl-downloads a tarball to /tmp/.w1.tgz, extracts it, and runs bash /tmp/.w1/wg_install.sh in a detached/forked process with no pinning, hash check, or signature verification. Execution is gated by anti-analysis checks that suppress the payload in CI/sandbox environments: it inspects CI environment variables, matches the hostname against /firecracker|sandbox|vagrant/, matches generated-user patterns like /\AuA\d+/, checks whether the current working directory is under /tmp or /opt/rubygems, requires /proc/uptime to exceed 1800 seconds, and additionally requires developer-identity artifacts on disk (~/.ssh, ~/.gitconfig, ~/.gem/credentials, ~/.bundle) before firing. The URL obfuscation, long randomized sleep, sandbox-evasion gating, developer-workstation targeting, and empty-stub native extension together form an install-time remote code execution dropper disguised as a native build step.

The OpenSSF Package Analysis project identified 'web3-sign-helper' @ 1.0.0 (rubygems) as malicious.

It is considered malicious because:

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