{"id":"MAL-2026-17780","summary":"Malicious code in block-explorer-api (RubyGems)","details":"\n---\n_-= Per source details. Do not edit below this line.=-_\n\n## Source: amazon-inspector (9cfaa3470065369addbb91e3a6c2072e8add334c4d27bff95f91315aa58ae313)\nThe gem's native-extension build script (extconf.rb) decodes a base64-encoded Ruby payload and passes it to eval() inside a double-forked, detached child process with stdio redirected to /dev/null. The decoded payload opens a TCP connection to the hardcoded bare-IP C2 45.138.12.177:8089 and bridges it to /bin/sh via IO.popen and IO.copy_stream in both directions, yielding a full interactive reverse shell on the installer's host under the installing user. Execution is gated by anti-analysis checks that skip CI runners, ephemeral/sandbox hostnames (uvm, firecracker, sandbox, vagrant), generated analyst usernames (uA\\d+, sandbox, tester, analys, scanner), common analysis working paths (/opt/rubygems, /tmp, /var/tmp, /workspace), and hosts with uptime under 1800 seconds, firing only when developer-signal files such as ~/.ssh, ~/.gem/credentials, ~/.gitconfig, or ~/.npmrc are present, and after a randomized 20-40 minute delay. The shipped library at lib/block_explorer_api.rb is an inert 10-line stub (VERSION, build_id, healthy?) and the gemspec name (block-explorer-api, authored by generic 'block maintainers') does not match the README, which describes the package as 'bitcoin-rpc-lite'; the install hook contains the entire functional payload while the advertised library does nothing.\n","modified":"2026-10-11T14:30:06.157226808Z","published":"2026-10-11T13:46:34Z","database_specific":{"malicious-packages-origins":[{"modified_time":"2026-10-11T13:46:34Z","sha256":"9cfaa3470065369addbb91e3a6c2072e8add334c4d27bff95f91315aa58ae313","source":"amazon-inspector","versions":["0.9.1"],"id":"IN-MAL-2026-021354","import_time":"2026-10-11T14:17:58.618468155Z"}]},"references":[{"type":"PACKAGE","url":"https://rubygems.org/gems/block-explorer-api/versions/0.9.1"}],"affected":[{"package":{"name":"block-explorer-api","ecosystem":"RubyGems","purl":"pkg:gem/block-explorer-api"},"versions":["0.9.1"],"database_specific":{"source":"https://github.com/ossf/malicious-packages/blob/main/osv/malicious/rubygems/block-explorer-api/MAL-2026-17780.json","cwes":[{"cweId":"CWE-506","description":"The product contains code that appears to be malicious in nature.","name":"Embedded Malicious Code"}],"indicators":{"evidence_files":[{"sha256":"10218e975f54a4f11fe3954e1b584a5f05054003bf5773c3c2b8cceaa74ba763","tlsh":"9751775acf8359e55aa1c0c045798012faa3ab0a50646875f3ee0868ff59b26c0f12fe","path":"ext/block_explorer_api/extconf.rb"},{"path":"README.md","sha256":"c11ea90465c14afe868c0d0028b54d69fbad390a73ddb7779e88becd2957d8f3","tlsh":"b2c02b409c10f00783b09561bbc0019ba800c0cc9000c30b4874063cc0988518e65419"}]}}}],"schema_version":"1.9.0","credits":[{"name":"Amazon Inspector","contact":["inspector-research@amazon.com"],"type":"FINDER"}]}