{"id":"MAL-2026-12596","summary":"Malicious code in checkout-test-utils (npm)","details":"\n---\n_-= Per source details. Do not edit below this line.=-_\n\n## Source: amazon-inspector (48a8b1e3a04ac6f84ba6ee63bcb2c0dd466bba5e78fbded886694ea58c976057)\nThe package presents itself as a small helper library (deepMerge/sleep/retry/chunk) but its main entry requires./_support.js, which at load time downloads an opaque binary from string-fragment-obfuscated Cloudflare Workers hosts (oob-worker.cf103-070.workers.dev, oob-worker.cf101-adf.workers.dev, oob-worker.cf100-416.workers.dev) with a DNS TXT-based fallback that reassembles a base64 payload from sequentially numbered TXT records under *.dl.wel1.ru (sdk./ext./pkg./net.dl.wel1.ru). The fetched bytes are written to /tmp under a disguised name (e.g., dotnet_diag_*.exe,.cache_*), chmod 0755, and executed detached via spawn('/bin/sh', ['-c', fp + ' &']). Destination hostnames are assembled via split-array joins to evade static matching (e.g., ['oob','-worker.cf103-070.w','orker','s.dev'].join('')). No hash or signature verification is performed, and the destinations are not publisher infrastructure. Any consumer that installs or requires this package auto-executes attacker-controlled code on the host.\n","modified":"2026-08-05T14:35:41.563355239Z","published":"2026-08-05T14:07:39Z","database_specific":{"malicious-packages-origins":[{"id":"IN-MAL-2026-015175","import_time":"2026-08-05T14:20:09.692492522Z","modified_time":"2026-08-05T14:07:39Z","sha256":"48a8b1e3a04ac6f84ba6ee63bcb2c0dd466bba5e78fbded886694ea58c976057","source":"amazon-inspector","versions":["35.1.3"]}]},"references":[{"type":"PACKAGE","url":"https://www.npmjs.com/package/checkout-test-utils/v/35.1.3"}],"affected":[{"package":{"name":"checkout-test-utils","ecosystem":"npm","purl":"pkg:npm/checkout-test-utils"},"versions":["35.1.3"],"database_specific":{"cwes":[{"description":"The product contains code that appears to be malicious in nature.","name":"Embedded Malicious Code","cweId":"CWE-506"}],"indicators":{"evidence_files":[{"sha256":"62c61ff92bdd339261e798f8234add8d1af4a63372ee2723f03527a5dc012462","tlsh":"3ea1969b026670198bb0ebe08717541af65be66337c0c1c4fb9c69841f7212483b2efc","path":"_support.js"},{"path":"index.js","sha256":"ba78a10c4bcdd0bfcd034efbf8b05dc7e0e0baf7ea5733142209ebbf78cd7bc4","tlsh":"4011bd8b2160706502727736e793c116fc2a8422a972826cf98c67d12f71d214ab5eda"}],"package_integrity":[{"filename":"checkout-test-utils-35.1.3.tgz","hashes":{"sha512_sri":"sha512-qz47jw/Lbk8OKC13rrkp/n8+dg1MihCu7BXpNv7D/GLT4rWUZniduRivBScKumxxoft2y1z9v8P1M0gSiFswBg==","sha1":"83db7a446aa2da0f1fad10ff2ef18d9aa29fb2e7"}}]},"source":"https://github.com/ossf/malicious-packages/blob/main/osv/malicious/npm/checkout-test-utils/MAL-2026-12596.json"}}],"schema_version":"1.8.0","credits":[{"name":"Amazon Inspector","contact":["inspector-research@amazon.com"],"type":"FINDER"}]}