{"id":"MAL-2026-17609","summary":"Malicious code in merkle-proof-lite (RubyGems)","details":"RubyGems runs this gem's native extension script `ext/merkle-proof-lite/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.\n\n---\n_-= Per source details. Do not edit below this line.=-_\n\n## Source: amazon-inspector (566447bbe57c81d3ad0e7f640951edd848b5a843c8b423ca370d96938d803cba)\nThe gem declares a native extension whose only real content is a 2-line empty Init stub in ext/merkle-proof-lite/merkle-proof-lite.c; no genuine native code is built. extconf.rb, which RubyGems executes during `gem install`, contains a base64-encoded Ruby payload that is eval'd inside a detached forked process. The decoded payload XOR-decodes a hardcoded URL to http://45.138.128.177:8092/wgkit.tar.gz, downloads it over plain HTTP to /tmp/.w1.tgz via curl, extracts it, and executes wg_install.sh under bash. Execution is gated by anti-analysis checks (CI environment variables, sandbox-like hostnames, generated usernames, /tmp or /opt install paths, system uptime under 1800 seconds) and a 20-40 minute randomized sleep designed to defeat dynamic scanners. The dropper only fires on hosts where developer-signal files such as ~/.ssh, ~/.gitconfig, and ~/.gem/credentials exist. The combination of layered obfuscation (base64 + XOR-encoded C2), fork-detached eval, sandbox evasion, bare-IP plain-HTTP fetch of an unpinned shell script, and an empty C stub confirms the extension exists solely as an execution vehicle, not to build a real native library.\n","modified":"2026-10-05T23:45:04.914593054Z","published":"2026-10-05T09:30:00Z","database_specific":{"iocs":{"ips":["45.138.12.177"],"urls":["http://45.138.12.177:8092/wgkit.tar.gz"],"files":[{"digests":{"sha256":"ddde0158956f75e9090e4a7992528bd281312208cbdc4479dc850e434745e480"},"note":"Native extension script that RubyGems runs at install time. It gates on the environment and starts the payload.","paths":["ext/merkle-proof-lite/extconf.rb"],"source":"PACKAGE_ARCHIVE"},{"note":"Second-stage archive and install script downloaded and run by the payload.","paths":["/tmp/.w1.tgz","/tmp/.w1/wg_install.sh"],"source":"DROPPED"}]},"malicious-packages-origins":[{"id":"IN-MAL-2026-021062","import_time":"2026-10-05T16:22:55.744136085Z","modified_time":"2026-10-05T15:58:41Z","sha256":"566447bbe57c81d3ad0e7f640951edd848b5a843c8b423ca370d96938d803cba","source":"amazon-inspector","versions":["1.0.0"]}]},"references":[{"type":"PACKAGE","url":"https://rubygems.org/gems/merkle-proof-lite/versions/1.0.0"},{"type":"REPORT","url":"https://safedep.io/rubygems-crypto-gems-install-time-reverse-shell/"}],"affected":[{"package":{"name":"merkle-proof-lite","ecosystem":"RubyGems","purl":"pkg:gem/merkle-proof-lite"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.0.0"],"database_specific":{"cwes":[{"name":"Embedded Malicious Code","cweId":"CWE-506","description":"The product contains code that appears to be malicious in nature."},{"cweId":"CWE-506","description":"The product contains code that appears to be malicious in nature.","name":"Embedded Malicious Code"}],"indicators":{"evidence_files":[{"tlsh":"6151ca568b8395f64db1d0d044359412fb667b0e6068a864f3de0868ab5af2ad4f02fd","path":"ext/merkle-proof-lite/extconf.rb","sha256":"ddde0158956f75e9090e4a7992528bd281312208cbdc4479dc850e434745e480"},{"tlsh":"cb9002c3953860434044a6b66329890680e0b6788d547245ad4761e0a5612d53aa61b1","path":"ext/merkle-proof-lite/merkle-proof-lite.c","sha256":"ffc2301e10394df2beb566eeea583de4e229c3ea58390d7dfadf68a14a97f0ae"}]},"source":"https://github.com/ossf/malicious-packages/blob/main/osv/malicious/rubygems/merkle-proof-lite/MAL-2026-17609.json"}}],"schema_version":"1.9.0","credits":[{"name":"Amazon Inspector","contact":["inspector-research@amazon.com"],"type":"FINDER"},{"name":"SafeDep","contact":["https://safedep.io"],"type":"FINDER"}]}