MAL-2026-12654

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Import Source
https://github.com/ossf/malicious-packages/blob/main/osv/malicious/npm/cobrowsing-exception-filter/MAL-2026-12654.json
JSON Data
https://api.osv.dev/v1/vulns/MAL-2026-12654
Published
2026-08-05T13:59:16Z
Modified
2026-08-05T14:36:09.642389301Z
Summary
Malicious code in cobrowsing-exception-filter (npm)
Details

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

Source: amazon-inspector (715fc9a652bf5d69755ea21ef2a906c318c511fe433df0721a13e266c3646832)

On require() of cobrowsing-exception-filter, index.js unconditionally loads support.js, which selects a platform-specific endpoint from a hardcoded list of obfuscated hosts (Cloudflare Workers subdomains such as oob-worker.cf*.workers.dev, with a DNS-TXT fallback under *.dl.wel1.ru). The endpoint hostnames are reassembled at runtime from split fragments (e.g. ["oob-worker.cf100-416.workers.de","v"].join("") and ["sdk.dl.wel1.r","u"].join("")) to evade static analysis. The code downloads opaque bytes, writes them to /var/tmp or %TEMP% under disguised filenames (.cache<hex>, dotnetdiag<hex>.exe), chmods 0755, and spawns the binary detached via /bin/sh or cmd.exe. A TTL marker (analyticsstate) rate-limits re-execution, and a DISABLETELEMETRY gate is used as cover-story framing. No hash/signature verification is performed, the hosts are attacker-controlled and mutable, and neither the fetched bytes nor the sibling 81KB lib/telemetry.js match any declared library purpose. The package name suggests an error-handling utility, but the shipped code has no such functionality.

Database specific 
{
    "malicious-packages-origins": [
        {
            "modified_time": "2026-08-05T13:59:16Z",
            "id": "IN-MAL-2026-015119",
            "import_time": "2026-08-05T14:20:04.022386811Z",
            "versions": [
                "35.8.3"
            ],
            "source": "amazon-inspector",
            "sha256": "715fc9a652bf5d69755ea21ef2a906c318c511fe433df0721a13e266c3646832"
        }
    ]
}
References
Credits

Affected packages

npm / cobrowsing-exception-filter

Package

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

Affected ranges

Affected versions

35.*
35.8.3

Database specific

cwes 
[
    {
        "cweId": "CWE-506",
        "name": "Embedded Malicious Code",
        "description": "The product contains code that appears to be malicious in nature."
    }
]
indicators 
{
    "package_integrity": [
        {
            "hashes": {
                "sha512_sri": "sha512-BOI/gXCMUsT7l3EJvAnAisz1xNBzTOIuDdDwaE2HwYeEJ2VXnInPuepmfNCuzYTQXbZzXSz6F29+TmvyXUBN+Q==",
                "sha1": "99d9106aa9e19e56789cefb2c7511856c25d7174"
            },
            "filename": "cobrowsing-exception-filter-35.8.3.tgz"
        }
    ],
    "evidence_files": [
        {
            "path": "_support.js",
            "tlsh": "fca1a66a15a670088b70d7e4c6175416f66bf6633781d288fb9c55880fb712883f2efc",
            "sha256": "310a56d19cb5a15a545de379ca2e1e307404be0ac27ec22d0147304efe25b083"
        },
        {
            "path": "lib/telemetry.js",
            "tlsh": "3c835056566a142186b2b368df234107ff3685272643429dbafc82dc1fbd72092a5ffc",
            "sha256": "38541bbd5a884c437c24e2769bc38872cb905792c3f928aad438e781c4cd7027"
        }
    ]
}
source 
"https://github.com/ossf/malicious-packages/blob/main/osv/malicious/npm/cobrowsing-exception-filter/MAL-2026-12654.json"