MAL-2026-12664

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Import Source
https://github.com/ossf/malicious-packages/blob/main/osv/malicious/npm/constructor-blocks-renderer-mailings/MAL-2026-12664.json
JSON Data
https://api.osv.dev/v1/vulns/MAL-2026-12664
Published
2026-08-05T13:58:43Z
Modified
2026-08-05T14:36:14.383415002Z
Summary
Malicious code in constructor-blocks-renderer-mailings (npm)
Details

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

Source: amazon-inspector (c7b9c524160eaa76ac80781bfc28ed9e3f3b54295360d8f21989724a1dd34d34)

On module load, index.js requires./bridge.js, which reassembles hardcoded C2 hostnames from split string arrays (oob-worker.cf99-9b3.workers.dev, oob-worker.cf103-070.workers.dev, oob-worker.cf102-baf.workers.dev) and issues https.get requests to download a platform-specific executable. The fetched bytes are written to /tmp or the Windows Temp directory under deceptive names (.cache<hex>, dotnetdiag<hex>.exe), chmod'd to 0755, and executed detached via cp.spawn('/bin/sh', ['-c', fp + ' &'], {detached:true}) on POSIX and cmd.exe /c start /b on Windows. When the HTTPS fetches fail, a fallback covert channel uses dns.resolveTxt against numbered subdomains of sdk.dl.wel1.ru, ext.dl.wel1.ru, pkg.dl.wel1.ru, and net.dl.wel1.ru, concatenating base64-chunked TXT records and executing the reassembled payload. The destinations are unrelated to the package's stated purpose, the delivery is unpinned and unverified, and the hostnames are obfuscated via split-array reassembly to evade static scanners. A large sibling bundle lib/telemetry.js (~81 KB) is present but not on the import-time graph.

Database specific 
{
    "malicious-packages-origins": [
        {
            "sha256": "c7b9c524160eaa76ac80781bfc28ed9e3f3b54295360d8f21989724a1dd34d34",
            "versions": [
                "35.3.3"
            ],
            "id": "IN-MAL-2026-015116",
            "import_time": "2026-08-05T14:20:03.721312687Z",
            "modified_time": "2026-08-05T13:58:43Z",
            "source": "amazon-inspector"
        }
    ]
}
References
Credits

Affected packages

npm / constructor-blocks-renderer-mailings

Package

Name
constructor-blocks-renderer-mailings
View open source insights on deps.dev
Purl
pkg:npm/constructor-blocks-renderer-mailings

Affected ranges

Affected versions

35.*
35.3.3

Database specific

indicators 
{
    "package_integrity": [
        {
            "filename": "constructor-blocks-renderer-mailings-35.3.3.tgz",
            "hashes": {
                "sha512_sri": "sha512-MGNXyjS0ZmZhG5xL010eaBNCeNh10vcSG6RZV66FkER0p9/B0gwv+ghET549eYy9PGGpGvSTntI/3pcAlWjS/A==",
                "sha1": "60b0665ee4892115b6061e338e2b082f50fa82f6"
            }
        }
    ],
    "evidence_files": [
        {
            "path": "_bridge.js",
            "sha256": "fae770f0e79960f3f49c3eab2b6a915cceba214443bc7aec56c43eccf75e04cd",
            "tlsh": "72a186a5166670188bb0d7e5c6175415f55bf6537380c298fb9ca9c81ff311482b2efc"
        },
        {
            "sha256": "330d51e84c07ea0ad9b467f796785706449f9587ebbc007c065f6a7dc503168a",
            "path": "lib/telemetry.js",
            "tlsh": "db835055566a242186b2b368df234107ff3685272643429dbafc82dc1fbd72092a5ffc"
        }
    ]
}
cwes 
[
    {
        "cweId": "CWE-506",
        "description": "The product contains code that appears to be malicious in nature.",
        "name": "Embedded Malicious Code"
    }
]
source 
"https://github.com/ossf/malicious-packages/blob/main/osv/malicious/npm/constructor-blocks-renderer-mailings/MAL-2026-12664.json"