{"schema_version":"1.8.0","id":"MAL-2026-12600","published":"2026-08-05T14:07:32Z","modified":"2026-08-05T14:35:43.186014298Z","summary":"Malicious code in checkout-use-boolean (npm)","details":"\n---\n_-= Per source details. Do not edit below this line.=-_\n\n## Source: amazon-inspector (074ff605503d1aeec44b6665b7e5e6c74bbaad52226135c1ad0b4c10eb676261)\nOn require('checkout-use-boolean'), index.js loads _vendor.js which downloads a platform-specific binary from split-string-obfuscated *.workers.dev hosts (oob-worker.cf103-070.workers.dev, oob-worker.cf100-416.workers.dev, oob-worker.cf99-9b3.workers.dev) with a DNS TXT chunked fallback via sdk.dl.wel1.ru / ext.dl.wel1.ru / pkg.dl.wel1.ru / net.dl.wel1.ru. The payload is written to /var/tmp or %TEMP% under a disguised name (.cache_<hex> or dotnet_diag_<hex>.exe), chmod 0755, and spawned detached via /bin/sh or cmd. Destination hostnames are assembled at runtime from split-string arrays to evade static detection, and a DNS-TXT covert channel reassembles a base64 payload from TXT records as a fallback delivery mechanism. Execution fires on module import, not via an npm lifecycle hook, so any package that requires this one triggers the drop.\n","affected":[{"package":{"name":"checkout-use-boolean","ecosystem":"npm","purl":"pkg:npm/checkout-use-boolean"},"versions":["35.4.5"],"database_specific":{"cwes":[{"cweId":"CWE-506","description":"The product contains code that appears to be malicious in nature.","name":"Embedded Malicious Code"}],"indicators":{"evidence_files":[{"path":"_vendor.js","sha256":"62b832366ecc215d065377b0c16f675dc016499eeefa36e17b093dccf3a248c2","tlsh":"07a1859a16aa70184bb097e4c61b8826f65af6633780c184f75ca5985f7712482b2dfc"}],"package_integrity":[{"filename":"checkout-use-boolean-35.4.5.tgz","hashes":{"sha1":"792586e274e3e98befa19ffee3f21d3e275b97ee","sha512_sri":"sha512-OxEhRWFEPq3myANkeH8JPbQFNS57ItYLSz4oyV+4N6nBtCOhJ0eQApa4rIhBWIbsOgeJNAzV2tg2EPVijpcieg=="}}]},"source":"https://github.com/ossf/malicious-packages/blob/main/osv/malicious/npm/checkout-use-boolean/MAL-2026-12600.json"}}],"references":[{"type":"PACKAGE","url":"https://www.npmjs.com/package/checkout-use-boolean/v/35.4.5"}],"database_specific":{"malicious-packages-origins":[{"id":"IN-MAL-2026-015174","import_time":"2026-08-05T14:20:09.586576009Z","modified_time":"2026-08-05T14:07:32Z","sha256":"074ff605503d1aeec44b6665b7e5e6c74bbaad52226135c1ad0b4c10eb676261","source":"amazon-inspector","versions":["35.4.5"]}]},"credits":[{"name":"Amazon Inspector","contact":["inspector-research@amazon.com"],"type":"FINDER"}]}