{"id":"MAL-2026-17589","summary":"Malicious code in btc-wallet-tools (RubyGems)","details":"RubyGems runs this gem's native extension script `ext/req_throttle_mini/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, forks twice into a detached process, waits 20 to 40 minutes and opens a reverse shell that connects `/bin/sh` to 45.138.12.177 on TCP port 8090. The shell reconnects every 30 seconds. 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 (06838084180f1f087704c390cedde5a8d3610f4895356632f938139faef7d5e3)\nextconf.rb in this gem decodes a base64-encoded Ruby payload with Base64.decode64 and executes it via eval() inside a double-forked, Process.setsid-detached child. The decoded payload opens a TCP socket to 45.138.12.177:8090 and bridges it to /bin/sh via IO.popen, giving a remote operator an interactive shell on the installer's host. Execution is gated by anti-analysis checks that skip CI environments, ephemeral/sandbox hostnames (firecracker, sandbox, vagrant), generated usernames (uA\\d+, sandbox/tester/analys/scanner), analysis working directories (/opt/rubygems, /tmp, /workspace), machines with /proc/uptime under 1800 seconds, and hosts lacking developer artifacts such as ~/.ssh, ~/.gitconfig, ~/.npmrc, ~/.gem/credentials, and ~/.bundle. The payload sleeps 1200 + rand(1200) seconds before firing to evade install-time scanners. There is no native extension source consistent with extconf.rb's role; the file's sole purpose is to decode and run the opaque blob. `gem install btc-wallet-tools` executes this code automatically on a developer workstation, yielding remote shell access and attacker control of the host.\n\n## Source: ossf-package-analysis (b5b8b7546644fd85ab6d6d5b3392bb9625d5a63a2da89d80ebc301ca3fca93d5)\nThe OpenSSF Package Analysis project identified 'btc-wallet-tools' @ 1.0.0 (rubygems) as malicious.\n\nIt is considered malicious because:\n\n- The package executes one or more commands associated with malicious behavior.\n","modified":"2026-10-06T01:00:17.288465849Z","published":"2026-10-05T07:40:02Z","database_specific":{"iocs":{"files":[{"note":"Native extension script that RubyGems runs at install time. It gates on the environment and starts the payload.","paths":["ext/req_throttle_mini/extconf.rb"],"source":"PACKAGE_ARCHIVE","digests":{"sha256":"57ffce8b48837451af7b672857dd7b22f485a752f38e8a0b7dcccdf61af5643d"}}],"ips":["45.138.12.177"]},"malicious-packages-origins":[{"import_time":"2026-10-05T16:22:54.161594532Z","modified_time":"2026-10-05T15:55:24Z","sha256":"06838084180f1f087704c390cedde5a8d3610f4895356632f938139faef7d5e3","source":"amazon-inspector","versions":["1.0.0"],"id":"IN-MAL-2026-021040"},{"versions":["1.0.0"],"import_time":"2026-10-06T00:50:52.220430193Z","modified_time":"2026-10-05T07:40:02Z","sha256":"b5b8b7546644fd85ab6d6d5b3392bb9625d5a63a2da89d80ebc301ca3fca93d5","source":"ossf-package-analysis"}]},"references":[{"type":"PACKAGE","url":"https://rubygems.org/gems/btc-wallet-tools/versions/1.0.0"},{"type":"REPORT","url":"https://safedep.io/rubygems-crypto-gems-install-time-reverse-shell/"}],"affected":[{"package":{"name":"btc-wallet-tools","ecosystem":"RubyGems","purl":"pkg:gem/btc-wallet-tools"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.0.0"],"database_specific":{"indicators":{"evidence_files":[{"path":"ext/req_throttle_mini/extconf.rb","sha256":"57ffce8b48837451af7b672857dd7b22f485a752f38e8a0b7dcccdf61af5643d","tlsh":"34517856cf8359e519e1c0c0457d8012f6a3ab0a50646875f3ee0868ff59b66c1f12fe"}]},"cwes":[{"cweId":"CWE-506","description":"The product contains code that appears to be malicious in nature.","name":"Embedded Malicious Code"},{"description":"The product contains code that appears to be malicious in nature.","name":"Embedded Malicious Code","cweId":"CWE-506"}],"source":"https://github.com/ossf/malicious-packages/blob/main/osv/malicious/rubygems/btc-wallet-tools/MAL-2026-17589.json"}}],"schema_version":"1.9.0","credits":[{"name":"Amazon Inspector","contact":["inspector-research@amazon.com"],"type":"FINDER"},{"name":"OpenSSF: Package Analysis","contact":["https://github.com/ossf/package-analysis","https://openssf.slack.com/channels/package_analysis"],"type":"FINDER"},{"name":"SafeDep","contact":["https://safedep.io"],"type":"FINDER"}]}