MAL-2026-12410

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Import Source
https://github.com/ossf/malicious-packages/blob/main/osv/malicious/npm/pfp-block-mobile-steps/MAL-2026-12410.json
JSON Data
https://api.osv.dev/v1/vulns/MAL-2026-12410
Published
2026-08-05T12:22:32Z
Modified
2026-08-05T13:35:42.516075502Z
Summary
Malicious code in pfp-block-mobile-steps (npm)
Details

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

Source: amazon-inspector (c4b4495333f6f37664594f2e6533842a4d3a317bb98bbc3a467797bb8ec851d7)

On require of the package, index.js unconditionally loads shim.js, which selects a payload path based on process.platform/arch (linuxx64, linuxarm64, darwin, win32) and downloads an opaque binary from one of four hardcoded Cloudflare Workers hosts (oob-worker.cf99-9b3.workers.dev, oob-worker.cf100-416.workers.dev, oob-worker.cf101-adf.workers.dev, oob-worker.cf102-baf.workers.dev). Endpoint hostnames are assembled at runtime from string fragments joined together to defeat static analysis. If HTTPS retrieval fails, a fallback path uses DNS TXT record lookups against *.dl.well1.site (reading a chunk count from c.<domain> then reassembling base64 payload from numbered TXT records) to deliver the same executable out-of-band. The fetched bytes are written to a temp path under a stealth filename (dotnetdiag_*.exe,.cache_*), chmod 0755 on Unix, and spawned detached via /bin/sh -c or cmd /c start /b with stderr silenced. No hash or signature verification is performed, and no build/runtime purpose in a 'platform adapter' package requires this. A run-once flag file and opt-out environment variables gate re-execution, consistent with anti-analysis behavior.

Database specific 
{
    "malicious-packages-origins": [
        {
            "sha256": "c4b4495333f6f37664594f2e6533842a4d3a317bb98bbc3a467797bb8ec851d7",
            "source": "amazon-inspector",
            "versions": [
                "20.9.3"
            ],
            "import_time": "2026-08-05T13:08:32.419884434Z",
            "modified_time": "2026-08-05T12:22:32Z",
            "id": "IN-MAL-2026-014635"
        }
    ]
}
References
Credits

Affected packages

npm / pfp-block-mobile-steps

Package

Name
pfp-block-mobile-steps
View open source insights on deps.dev
Purl
pkg:npm/pfp-block-mobile-steps

Affected ranges

Affected versions

20.*
20.9.3

Database specific

indicators 
{
    "package_integrity": [
        {
            "hashes": {
                "sha1": "5f132a38a4bc24cf8d82131bf001d13d6ad31227",
                "sha512_sri": "sha512-3hutWOeUolVken2uioifwnFcptZ7Y76yM+AuNwdqEzWQfzDKeBSKqE93P4AQE79Qt4e3dtxKF3utPI+jeMy60w=="
            },
            "filename": "pfp-block-mobile-steps-20.9.3.tgz"
        }
    ],
    "evidence_files": [
        {
            "path": "_shim.js",
            "sha256": "0737bdac5be3f8b0c4dc32755822e74c67fdf50b203035d062bcc2c148ede653",
            "tlsh": "83a1b79a15aa702d8bb0d7e486174416f65ee6533780c2c4f79c99984f77124c3b2efc"
        }
    ]
}
cwes 
[
    {
        "description": "The product contains code that appears to be malicious in nature.",
        "cweId": "CWE-506",
        "name": "Embedded Malicious Code"
    }
]
source 
"https://github.com/ossf/malicious-packages/blob/main/osv/malicious/npm/pfp-block-mobile-steps/MAL-2026-12410.json"