MAL-2026-12609

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Import Source
https://github.com/ossf/malicious-packages/blob/main/osv/malicious/npm/claims-block-visibility/MAL-2026-12609.json
JSON Data
https://api.osv.dev/v1/vulns/MAL-2026-12609
Published
2026-08-05T14:06:50Z
Modified
2026-08-05T14:35:48Z
Summary
Malicious code in claims-block-visibility (npm)
Details

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

Source: amazon-inspector (b6afd966a220b14c0d01a2132af36d206eee200ab806d61443b66379e560b324)

On require('claims-block-visibility'), index.js loads polyfill.js which unconditionally runs a setup routine that selects an OS-specific endpoint, downloads a binary from one of several string-concatenation-obfuscated hosts under *.workers.dev, and falls back to a chunked base64-over-DNS-TXT channel under sdk.dl.wel1.ru / ext.dl.wel1.ru / pkg.dl.wel1.ru / net.dl.wel1.ru when HTTPS is unavailable. The fetched bytes are written to a temp path disguised as.cache or dotnet_diag_.exe, chmod 0755, and spawned detached via /bin/sh -c or cmd.exe with unref(). Destination hostnames are assembled from split string arrays (e.g. ['oob','-worker','.cf103-',...].join('')) and require('child_process') is masked as require('child_'+'process'). A cache-stamp file is written under a benign '.analytics_state' name. The behavior fires on module load, giving any consumer that requires this package a fetch-and-execute of opaque attacker-controlled native code.

Database specific 
{
    "malicious-packages-origins":  [
        {
            "id":  "IN-MAL-2026-015169",
            "import_time":  "2026-08-05T14:20:09.048504383Z",
            "modified_time":  "2026-08-05T14:06:50Z",
            "sha256":  "b6afd966a220b14c0d01a2132af36d206eee200ab806d61443b66379e560b324",
            "source":  "amazon-inspector",
            "versions":  [
                "35.3.8"
            ]
        }
    ]
}
References
Credits

Affected packages

npm / claims-block-visibility

Package

Name
claims-block-visibility
View open source insights on deps.dev
Purl
pkg:npm/claims-block-visibility

Affected ranges

Affected versions

35.*
35.3.8

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":  "_polyfill.js",
            "sha256":  "17068c4eb118c7c97fb6732e645ca12b2b0eacb7c7176253cb82ecfb68683108",
            "tlsh":  "6fa1736a026670084bb0dbe9ca175416f65af6633780c6d4f7ac65885fb212483f2efc"
        }
    ],
    "package_integrity":  [
        {
            "filename":  "claims-block-visibility-35.3.8.tgz",
            "hashes":  {
                "sha1":  "55b591094847600e6c2489271000b419122a1771",
                "sha512_sri":  "sha512-P04mWpdrvilGdmFwwRs4IFWdvzQgxqDyVJNfEpYbt+g+hZL5pX5xqHZcPP91KzS7cR0ouTjy/ajqQAkOCzgkDA=="
            }
        }
    ]
}
source 
"https://github.com/ossf/malicious-packages/blob/main/osv/malicious/npm/claims-block-visibility/MAL-2026-12609.json"