MAL-2026-12596

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Import Source
https://github.com/ossf/malicious-packages/blob/main/osv/malicious/npm/checkout-test-utils/MAL-2026-12596.json
JSON Data
https://api.osv.dev/v1/vulns/MAL-2026-12596
Published
2026-08-05T14:07:39Z
Modified
2026-08-05T14:35:41Z
Summary
Malicious code in checkout-test-utils (npm)
Details

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

Source: amazon-inspector (48a8b1e3a04ac6f84ba6ee63bcb2c0dd466bba5e78fbded886694ea58c976057)

The package presents itself as a small helper library (deepMerge/sleep/retry/chunk) but its main entry requires./support.js, which at load time downloads an opaque binary from string-fragment-obfuscated Cloudflare Workers hosts (oob-worker.cf103-070.workers.dev, oob-worker.cf101-adf.workers.dev, oob-worker.cf100-416.workers.dev) with a DNS TXT-based fallback that reassembles a base64 payload from sequentially numbered TXT records under *.dl.wel1.ru (sdk./ext./pkg./net.dl.wel1.ru). The fetched bytes are written to /tmp under a disguised name (e.g., dotnet_diag.exe,.cache_), chmod 0755, and executed detached via spawn('/bin/sh', ['-c', fp + ' &']). Destination hostnames are assembled via split-array joins to evade static matching (e.g., ['oob','-worker.cf103-070.w','orker','s.dev'].join('')). No hash or signature verification is performed, and the destinations are not publisher infrastructure. Any consumer that installs or requires this package auto-executes attacker-controlled code on the host.

Database specific 
{
    "malicious-packages-origins": [
        {
            "id": "IN-MAL-2026-015175",
            "import_time": "2026-08-05T14:20:09.692492522Z",
            "modified_time": "2026-08-05T14:07:39Z",
            "sha256": "48a8b1e3a04ac6f84ba6ee63bcb2c0dd466bba5e78fbded886694ea58c976057",
            "source": "amazon-inspector",
            "versions": [
                "35.1.3"
            ]
        }
    ]
}
References
Credits

Affected packages

npm / checkout-test-utils

Package

Name
checkout-test-utils
View open source insights on deps.dev
Purl
pkg:npm/checkout-test-utils

Affected ranges

Affected versions

35.*
35.1.3

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": "_support.js",
            "sha256": "62c61ff92bdd339261e798f8234add8d1af4a63372ee2723f03527a5dc012462",
            "tlsh": "3ea1969b026670198bb0ebe08717541af65be66337c0c1c4fb9c69841f7212483b2efc"
        },
        {
            "path": "index.js",
            "sha256": "ba78a10c4bcdd0bfcd034efbf8b05dc7e0e0baf7ea5733142209ebbf78cd7bc4",
            "tlsh": "4011bd8b2160706502727736e793c116fc2a8422a972826cf98c67d12f71d214ab5eda"
        }
    ],
    "package_integrity": [
        {
            "filename": "checkout-test-utils-35.1.3.tgz",
            "hashes": {
                "sha1": "83db7a446aa2da0f1fad10ff2ef18d9aa29fb2e7",
                "sha512_sri": "sha512-qz47jw/Lbk8OKC13rrkp/n8+dg1MihCu7BXpNv7D/GLT4rWUZniduRivBScKumxxoft2y1z9v8P1M0gSiFswBg=="
            }
        }
    ]
}
source 
"https://github.com/ossf/malicious-packages/blob/main/osv/malicious/npm/checkout-test-utils/MAL-2026-12596.json"