MAL-2026-6543

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Import Source
https://github.com/ossf/malicious-packages/blob/main/osv/malicious/npm/express-initial/MAL-2026-6543.json
JSON Data
https://api.osv.dev/v1/vulns/MAL-2026-6543
Published
2026-06-26T21:40:14Z
Modified
2026-06-26T22:46:40.509248856Z
Summary
Malicious code in express-initial (npm)
Details

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

Source: amazon-inspector (a8d292a4664135ed1869f907d62fb6472839ab54a59aedb2f3a88022a0c70095)

package.json declares "postinstall": "node index.js", so npm install express-initial automatically runs the package's main script. index.js is heavily obfuscated (obfuscator.io-style 317-entry RC4-encoded string array, base64 decoder, array-rotation self-shuffle, control-flow flattening) which hides the destination URL, AES key material, and command strings from any plain-text inspection. At runtime the script imports http/https, fs, path, os, crypto, and child_process, performs an HTTPS GET against a hard-coded remote host, splits the response on ':' into IV and ciphertext, decrypts via crypto.createDecipheriv('aes-256-...', <sha256-derived key>, Buffer.from(iv,'base64')), writes the decrypted bytes into path.join(os.tmpdir(), <name>) with flag 'w+', and immediately invokes the dropped file via child_process.exec/execFile with windowsHide: true. This is a fetch-decrypt-and-execute dropper firing on default install. The package name also leverages the popular express framework while shipping empty author/description/repository metadata and a generic README that itself notes the script is obfuscated — consistent with a deliberate supply-chain lure rather than a legitimate helper.

Database specific 
{
    "malicious-packages-origins": [
        {
            "versions": [
                "12.1.9"
            ],
            "source": "amazon-inspector",
            "modified_time": "2026-06-26T21:40:14Z",
            "sha256": "1ba96d5070924af79839d4dbc950b28c3f59ad9515890cf83f1d631a6678c120",
            "id": "IN-MAL-2026-007670",
            "ranges": [
                {
                    "type": "SEMVER",
                    "events": [
                        {
                            "introduced": "0"
                        }
                    ]
                }
            ],
            "import_time": "2026-06-26T22:30:41.298649551Z"
        },
        {
            "versions": [
                "12.1.10"
            ],
            "source": "amazon-inspector",
            "modified_time": "2026-06-26T21:40:25Z",
            "sha256": "a8d292a4664135ed1869f907d62fb6472839ab54a59aedb2f3a88022a0c70095",
            "id": "IN-MAL-2026-007671",
            "ranges": [
                {
                    "type": "SEMVER",
                    "events": [
                        {
                            "introduced": "0"
                        }
                    ]
                }
            ],
            "import_time": "2026-06-26T22:30:41.346416062Z"
        }
    ]
}
References
Credits

Affected packages

npm / express-initial

Package

Name
express-initial
View open source insights on deps.dev
Purl
pkg:npm/express-initial

Affected ranges

Type
SEMVER
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

12.*
12.1.9
12.1.10

Database specific

cwes 
[
    {
        "cweId": "CWE-506",
        "description": "The product contains code that appears to be malicious in nature.",
        "name": "Embedded Malicious Code"
    },
    {
        "cweId": "CWE-506",
        "description": "The product contains code that appears to be malicious in nature.",
        "name": "Embedded Malicious Code"
    }
]
indicators 
{
    "package_integrity": [
        {
            "filename": "express-initial-12.1.9.tgz",
            "hashes": {
                "sha512_sri": "sha512-VDv/DISstAYC5rkKglhg5QD1Tc6GX/j1wpRT1AKh/p0MtIwf8Ta8TtFbVUAgfgDTJfI0s1kZ4BpZBTPJ8f3R/g==",
                "sha1": "e60bc20725873207cc80e2d5ad3b47a5e4acbea4"
            }
        }
    ],
    "evidence_files": [
        {
            "path": "index.js",
            "tlsh": "c682778c3fd1b0a15633b0f77a1b6496f1795c88b38d8948f796f058fd28318e496b68",
            "sha256": "9ecade5bfc69696b2077c067bcb38d77ca75563ad1432b8a43acef5e87f0010b"
        },
        {
            "path": "package.json",
            "tlsh": "9bd097220e920a3366b046962c3a818bb2a04f2f24307c0b71ff053c42e33318cee718",
            "sha256": "1a736723cd34a5e32c8301b6a6858e3329712eeb6306f3f3962e5cb5f64cf9e5"
        }
    ]
}
source 
"https://github.com/ossf/malicious-packages/blob/main/osv/malicious/npm/express-initial/MAL-2026-6543.json"