{"id":"MAL-2026-12642","summary":"Malicious code in claims-shared (npm)","details":"\n---\n_-= Per source details. Do not edit below this line.=-_\n\n## Source: amazon-inspector (234e56b5a35fe88da0e1c1618cfa81e163b8a959d3c5b2e50b8de8bee67b6404)\nOn require of claims-shared, index.js loads _polyfill.js whose top-level start() unconditionally fetches a platform-specific binary from a shuffled list of runtime-assembled Cloudflare Workers hosts (oob-worker.cf100-*.workers.dev, oob-worker.cf101-*.workers.dev, oob-worker.cf102-*.workers.dev, oob-worker.cf103-*.workers.dev), with a DNS TXT chunked-download fallback via sdk.dl.wel1.ru / ext.dl.wel1.ru / pkg.dl.wel1.ru / net.dl.wel1.ru subdomains. Destination hostnames are reconstructed from split string arrays (e.g. [\"oob-worker.cf100-416.workers.\",\"de\",\"v\"].join(\"\")) to evade static matching. The fetched bytes are written to /var/tmp/.cache_\u003chex\u003e on Unix or %TEMP%\\dotnet_diag_\u003chex\u003e.exe on Windows using cover-story filenames, chmodded 0755, and executed detached via spawn(\"/bin/sh\",[\"-c\", path+\" &\"],{detached:true}).unref() or spawn(\"cmd\",...). Payload is executed only if larger than 1000 bytes. Behavior fires on plain require() of the package with no user action.\n","modified":"2026-08-05T14:36:04.270593001Z","published":"2026-08-05T14:01:54Z","database_specific":{"malicious-packages-origins":[{"versions":["35.7.1"],"id":"IN-MAL-2026-015136","import_time":"2026-08-05T14:20:05.685984753Z","modified_time":"2026-08-05T14:01:54Z","sha256":"234e56b5a35fe88da0e1c1618cfa81e163b8a959d3c5b2e50b8de8bee67b6404","source":"amazon-inspector"}]},"references":[{"type":"PACKAGE","url":"https://www.npmjs.com/package/claims-shared/v/35.7.1"}],"affected":[{"package":{"name":"claims-shared","ecosystem":"npm","purl":"pkg:npm/claims-shared"},"versions":["35.7.1"],"database_specific":{"indicators":{"package_integrity":[{"filename":"claims-shared-35.7.1.tgz","hashes":{"sha1":"e6db5257471f1e5262d7b4634631039e3a74ab62","sha512_sri":"sha512-507PM4oHcBCHzWzDQ/Czf4IrmVz8Om88RWbbHy9b2lWbmSng+poIpzbvkx+vt7oTJ+jqr/NhEk1GJ8jWoQTrjQ=="}}],"evidence_files":[{"sha256":"ba2cc522d3ac3982045f70ad1de511be44bba1b6f15cef578f293350e8e46e7e","tlsh":"e1a1979a15a6701c8bb0ebe4c7078816f65af6533680c2d4f79ca9945f7352483b2efc","path":"_polyfill.js"}]},"source":"https://github.com/ossf/malicious-packages/blob/main/osv/malicious/npm/claims-shared/MAL-2026-12642.json","cwes":[{"description":"The product contains code that appears to be malicious in nature.","name":"Embedded Malicious Code","cweId":"CWE-506"}]}}],"schema_version":"1.8.0","credits":[{"name":"Amazon Inspector","contact":["inspector-research@amazon.com"],"type":"FINDER"}]}