{"answers":{"affected":"1 open source package ship an affected version, including checkout-base-test.","exploited":"There is no known exploitation of MAL-2026-12544 in the wild and no public exploit code.","fix":"Remove the package from your dependencies and lockfiles, then rotate any secrets on machines where it was installed.","what":"MAL-2026-12544 is a malicious package in checkout-base-test, published on 5 Aug 2026."},"fix_prompt":"MAL-2026-12544 is a malicious package: checkout-base-test (npm). Every version was published to cause harm.\n\nTask:\n1. Search this repository's dependency manifests and lockfiles for the package, including transitive dependencies.\n2. If it is present, remove it, regenerate the lockfile with the project's package manager, and replace whatever it was used for.\n3. List any CI runners, developer machines or containers that installed it, so their secrets can be rotated.\n4. If the package is not used anywhere, say so and change nothing.\n\nReference: https://insights.sbomify.com/MAL-2026-12544/ (Markdown: https://insights.sbomify.com/MAL-2026-12544/index.md)","id":"MAL-2026-12544","markdown":"https://insights.sbomify.com/MAL-2026-12544/index.md","name":"MAL-2026-12544","record":{"aliases":[],"analysis":null,"analysis_generated_by":null,"assigner":null,"cpe":[],"cvss":{"score":null,"severity":null,"source":null,"vector":null,"version":null},"cwes":[],"description":"On require() of this package, index.js loads _helpers.js which runs at import time. The module assembles three attacker-controlled hostnames from split string fragments joined at runtime (oob-worker.cf99-9b3.workers.dev, oob-worker.cf101-adf.workers.dev, oob-worker.cf102-baf.workers.dev), selects a platform-specific endpoint, fetches an opaque binary via https.get, writes it to /var/tmp or %TEMP% under a disguised filename (.cache_\u003chex\u003e on POSIX, dotnet_diag_\u003chex\u003e.exe on Windows), chmods it 0755, and spawns it detached via spawn(\"/bin/sh\", [\"-c\",...]) or spawn(\"cmd\",...). A DNS-TXT chunked base64 covert-channel fallback contacts *.dl.wel1.ru when the HTTPS hosts are unreachable. Additional evasion: require(\"child_\" + \"process\") string concatenation in lib/telemetry.js, environment-variable gating on DISABLE_TELEMETRY / ANALYTICS_OPT_OUT / DO_NOT_TRACK, and a filesystem session stamp to fire once per host. The disguised filenames (dotnet_diag_,.cache_) impersonate legitimate diagnostic artifacts. The package name resembles a checkout/test utility but ships no functionality matching that purpose.","ecosystems":["npm"],"exploits":{"exploitdb":null,"first_seen":null,"github_poc":null,"max_poc_stars":null,"metasploit":null,"nuclei":null,"refs":[],"tier":null},"has_fix":false,"headline":"Malicious code in checkout-base-test (npm)","id":"MAL-2026-12544","indexable":true,"kev":null,"kind":"malicious","links":{"ecosystem":"npm","product":null,"products":[],"type":null,"year":"2026"},"n_packages":1,"n_references":null,"packages":[{"ecosystem":"npm","fixed":[],"introduced":[],"last_affected":[],"package":"checkout-base-test","purl":"pkg:npm/checkout-base-test","source":"MAL-2026-12544"}],"products":null,"published":"2026-08-05","related":[],"sources":[{"class":"attribution","licence":"Apache-2.0","name":"OpenSSF Malicious Packages","prefix":"MAL"}],"ssvc":{"automatable":null,"exploitation":null,"technical_impact":null},"state":null,"updated":null,"vendors":null},"summary":null,"url":"https://insights.sbomify.com/MAL-2026-12544/"}