Malicious code in block-explorer-api (RubyGems)

{
  "id": "4432809d92b23193b696e185846791ed0e5f703fc06ce256d3010f89ccb27de0",
  "url": "https://osv.dev/vulnerability/MAL-2026-17780",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Malicious code in block-explorer-api (RubyGems)",
    "summary": "--- _-= Per source details. Do not edit below this line.=-_ ## Source: amazon-inspector (9cfaa3470065369addbb91e3a6c2072e8add334c4d27bff95f91315aa58ae313) The 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. ## Source: ossf-package-analysis (a5b9d91f1bb",
    "evidence": "osv:MAL-2026-17780",
    "products": [
      {
        "name": {
          "value": "block-explorer-api",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "0.9.1",
            "evidence": "/affected/0/versions"
          }
        ]
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "MAL-2026-17780",
      "aliases": [
        "MAL-2026-17780"
      ],
      "affected": [
        {
          "package": {
            "name": "block-explorer-api",
            "purl": "pkg:gem/block-explorer-api",
            "ecosystem": "RubyGems"
          },
          "versions": [
            "0.9.1"
          ],
          "database_specific": {
            "cwes": [
              {
                "name": "Embedded Malicious Code",
                "cweId": "CWE-506",
                "description": "The product contains code that appears to be malicious in nature."
              }
            ],
            "source": "https://github.com/ossf/malicious-packages/blob/main/osv/malicious/rubygems/block-explorer-api/MAL-2026-17780.json",
            "indicators": {
              "evidence_files": [
                {
                  "path": "ext/block_explorer_api/extconf.rb",
                  "tlsh": "9751775acf8359e55aa1c0c045798012faa3ab0a50646875f3ee0868ff59b26c0f12fe",
                  "sha256": "10218e975f54a4f11fe3954e1b584a5f05054003bf5773c3c2b8cceaa74ba763"
                },
                {
                  "path": "README.md",
                  "tlsh": "b2c02b409c10f00783b09561bbc0019ba800c0cc9000c30b4874063cc0988518e65419",
                  "sha256": "c11ea90465c14afe868c0d0028b54d69fbad390a73ddb7779e88becd2957d8f3"
                }
              ]
            }
          }
        }
      ],
      "modified": "2026-10-13T23:30:05.074730284Z",
      "provider": "osv",
      "references": [
        "https://rubygems.org/gems/block-explorer-api/versions/0.9.1"
      ],
      "provider_metadata": {
        "malicious-packages-origins": [
          {
            "id": "IN-MAL-2026-021354",
            "sha256": "9cfaa3470065369addbb91e3a6c2072e8add334c4d27bff95f91315aa58ae313",
            "source": "amazon-inspector",
            "versions": [
              "0.9.1"
            ],
            "import_time": "2026-10-11T14:17:58.618468155Z",
            "modified_time": "2026-10-11T13:46:34Z"
          },
          {
            "sha256": "a5b9d91f1bb472b9d7f227bda95ad5ab56761514d73c202baa3ffdfa4f497cc0",
            "source": "ossf-package-analysis",
            "versions": [
              "0.9.1"
            ],
            "import_time": "2026-10-13T23:14:39.441219109Z",
            "modified_time": "2026-10-11T07:05:27Z"
          }
        ]
      }
    },
    "related_cves": [],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 313744,
  "published_at": "2026-10-11T07:05:27+00:00"
}