MAL-2026-12651

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Import Source
https://github.com/ossf/malicious-packages/blob/main/osv/malicious/npm/cobrowsing-cobrowsing-core/MAL-2026-12651.json
JSON Data
https://api.osv.dev/v1/vulns/MAL-2026-12651
Published
2026-08-05T13:59:23Z
Modified
2026-08-05T14:36:08.301915893Z
Summary
Malicious code in cobrowsing-cobrowsing-core (npm)
Details

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

Source: amazon-inspector (c27e38e295cce55b33b75d72a22db6deb6a851e7739111a1979f8317961465b9)

cobrowsing-cobrowsing-core@35.5.8 is a binary dropper disguised as a platform core package. On require()/import (index.js loads polyfill.js), the package selects a platform-specific payload for linuxx64, linuxarm64, darwin, or win32, fetches attacker-controlled bytes from Cloudflare Workers hosts under oob-worker.cf1xx-*.workers.dev, writes them to /var/tmp or %TEMP% under a disguised name (.cache<rand> on POSIX, dotnetdiag<rand>.exe on Windows), chmods to 0755, and spawns them detached via /bin/sh -c or cmd.exe. No signature or hash verification is performed. A DNS-TXT covert channel provides a fallback delivery path: loadViaDns() reads a count from a c.<domain> TXT record, then concatenates N numbered TXT records from sdk.dl.wel1.ru / ext.dl.wel1.ru / pkg.dl.wel1.ru / net.dl.wel1.ru, base64-decodes the result, and executes it. C2 hostnames and dangerous API names are reassembled at runtime from split fragments (e.g. ["oob-worker.cf103-070.w","ork","ers.","dev"].join(""), require("child_"+"process"), fs["chmod"+"Sync"]) as anti-scanner obfuscation. lib/telemetry.js is a second dropper implementation styled as a Sentry-like analytics SDK, containing the same primitives and confirming intent. Any consumer that installs and require()s this package executes attacker-controlled code on the installer's host.

Database specific 
{
    "malicious-packages-origins": [
        {
            "modified_time": "2026-08-05T13:59:23Z",
            "source": "amazon-inspector",
            "id": "IN-MAL-2026-015120",
            "import_time": "2026-08-05T14:20:04.106735242Z",
            "sha256": "c27e38e295cce55b33b75d72a22db6deb6a851e7739111a1979f8317961465b9",
            "versions": [
                "35.5.8"
            ]
        }
    ]
}
References
Credits

Affected packages

npm / cobrowsing-cobrowsing-core

Package

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

Affected ranges

Affected versions

35.*
35.5.8

Database specific

indicators 
{
    "package_integrity": [
        {
            "filename": "cobrowsing-cobrowsing-core-35.5.8.tgz",
            "hashes": {
                "sha512_sri": "sha512-Rb+0jiW9xPENm2MCBypgGAxs2U9xOjE3XS5MuE0t+s/x826FANt/pEI/qwtHbI/7y4uOdg87dt7DvanFdeZocg==",
                "sha1": "8ae1482ef0dc51f350f5ea30d134f91289de0050"
            }
        }
    ],
    "evidence_files": [
        {
            "tlsh": "5da1879a026b71198bb0d7e4c7175416f65bf663338082d8fa5c69981fb312443b2efc",
            "sha256": "5cba9994c402a51d91247bac24a0204d4812ba437aaa741da4fc3b1584f51d5c",
            "path": "_polyfill.js"
        },
        {
            "tlsh": "b2835055566a242186b2b368df234107ff3685272643429dbafc82dc1fbd72092a5ffc",
            "sha256": "f8b93e1d8ca5d015682184bcf24972a80fbf71cf60b2fe5cfecda0fa93f03eee",
            "path": "lib/telemetry.js"
        }
    ]
}
source 
"https://github.com/ossf/malicious-packages/blob/main/osv/malicious/npm/cobrowsing-cobrowsing-core/MAL-2026-12651.json"
cwes 
[
    {
        "name": "Embedded Malicious Code",
        "description": "The product contains code that appears to be malicious in nature.",
        "cweId": "CWE-506"
    }
]