cobrowsing-utils

{"modified":"2026-08-05T13:58:01Z","published":"2026-08-05T13:58:01Z","schema_version":"1.7.4","id":"MAL-2026-12659","summary":"Malicious code in cobrowsing-utils (npm)","details":"\n---\n_-= Per source details. Do not edit below this line.=-_\n\n## Source: amazon-inspector (a369ea5eb28ebfd7fddb1c5baa3fc22fb371761839c0a2bd7123df273acd2077)\ncobrowsing-utils@35.7.3 executes a binary dropper as a side effect of requiring the package. index.js loads _helpers.js which auto-runs main() at import time. main() assembles Cloudflare Workers hostnames from split string fragments (e.g. oob-worker.cf101-adf.workers.dev, oob-worker.cf99-9b3.workers.dev, oob-worker.cf102-baf.workers.dev), fetches a platform-specific binary via https.get, writes it to /var/tmp or %TEMP% under masquerading names (.cache_<hex>, dotnet_diag_<hex>.exe, analytics_state), chmods 0755, and spawns it detached via /bin/sh -c \"<path> &\" or cmd.exe /c start /b. When HTTPS fetch fails, the code falls back to a DNS-TXT covert channel: it queries c.<domain> under *.dl.wel1.ru subdomains (sdk.dl.wel1.ru, ext.dl.wel1.ru, pkg.dl.wel1.ru, net.dl.wel1.ru) for a chunk count, reassembles indexed TXT records, base64-decodes the payload, writes it to disk, and executes it. Hostnames, discovery domains, file names, and function identifiers are chosen to blend with legitimate telemetry (_l, _p, _activate, analytics_state, dotnet_diag_). The package advertises itself as shared utilities; the fetched binary has no relation to that stated purpose.\n","affected":[{"package":{"ecosystem":"npm","name":"cobrowsing-utils"},"versions":["35.7.3"],"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":"_helpers.js","sha256":"a7b492b417a1b23a86ca5b0d7780f214f3e156b979364b7c73c8f65fde1ac214","tlsh":"b7a1a45a16aa70098bb09be0c7175819f65ef6633380c2d4fb5c65981fb716483b2efc"}],"package_integrity":[{"filename":"cobrowsing-utils-35.7.3.tgz","hashes":{"sha1":"17658e62415bad39f31f0f01246f8a32838c9212","sha512_sri":"sha512-y+FDhIDSieYrKwDoIRH2L0zQsquRSaF6X/XPX5WIGGiX5TI7wTUi65tEUT/ojGe5E7Q6aRmNfinBrf/MDe28rw=="}}]}}}],"references":[{"type":"PACKAGE","url":"https://www.npmjs.com/package/cobrowsing-utils/v/35.7.3"}],"credits":[{"name":"Amazon Inspector","type":"FINDER","contact":["inspector-research@amazon.com"]}],"database_specific":{"malicious-packages-origins":[{"id":"IN-MAL-2026-015111","import_time":"2026-08-05T14:20:03.180661966Z","modified_time":"2026-08-05T13:58:01Z","sha256":"a369ea5eb28ebfd7fddb1c5baa3fc22fb371761839c0a2bd7123df273acd2077","source":"amazon-inspector","versions":["35.7.3"]}]}}