hdkey-derive-helperRubyGems

RubyGems runs this gem's native extension script ext/hdkey-derive-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 presents itself as a BIP32/mnemonic derivation helper but ships only a wordlist stub and a 56-byte empty C file (ext/hdkey-derive-helper/hdkey-derive-helper.c, body void Init_HdkeyDeriveHelper(void) {}) registered as a native extension. Because RubyGems auto-executes extconf.rb during gem install, the extension exists solely as an execution vehicle. extconf.rb contains no build logic; it base64-decodes a Ruby payload, reconstructs a destination URL by XOR-decoding a hex blob with a 4-byte key, and in a detached fork downloads a tarball with curl, extracts it to /tmp/.w1, and runs bash wg_install.sh on the extracted contents. The reconstructed destination is http://45.138.127.89:8092/wgkit.tar.gz — a bare-IP endpoint over plain HTTP, unrelated to any publisher. Execution is gated by anti-analysis checks that refuse to run under CI environment variables, ephemeral/sandbox hostnames, generated usernames matching patterns such as uA\d+/sandbox/tester/analys/scanner, temp or analysis cwd paths, or machine uptime under 30 minutes, and that require developer artifacts (~/.ssh, ~/.gitconfig, ~/.npmrc, ~/.gem/credentials, ~/.bundle) to be present. A randomized 20–40 minute sleep further delays detonation. The combination of a cover-story crypto-wallet name, an empty native extension used purely to trigger install-time shell, multi-layer obfuscation of the C2 URL, developer-workstation targeting, and sandbox evasion is a confirmed install-time dropper against developer machines.

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

It is considered malicious because:

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