MAL-2026-12659

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Import Source
https://github.com/ossf/malicious-packages/blob/main/osv/malicious/npm/cobrowsing-utils/MAL-2026-12659.json
JSON Data
https://api.osv.dev/v1/vulns/MAL-2026-12659
Published
2026-08-05T13:58:01Z
Modified
2026-08-05T14:36:11Z
Summary
Malicious code in cobrowsing-utils (npm)
Details

-= Per source details. Do not edit below this line.=-

Source: amazon-inspector (a369ea5eb28ebfd7fddb1c5baa3fc22fb371761839c0a2bd7123df273acd2077)

cobrowsing-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, dotnet_diag_.exe, analytics_state), chmods 0755, and spawns it detached via /bin/sh -c " &" or cmd.exe /c start /b. When HTTPS fetch fails, the code falls back to a DNS-TXT covert channel: it queries c. 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.

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"
            ]
        }
    ]
}
References
Credits

Affected packages

npm / cobrowsing-utils

Package

Name
cobrowsing-utils
View open source insights on deps.dev
Purl
pkg:npm/cobrowsing-utils

Affected ranges

Affected versions

35.*
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=="
            }
        }
    ]
}
source 
"https://github.com/ossf/malicious-packages/blob/main/osv/malicious/npm/cobrowsing-utils/MAL-2026-12659.json"