The zer0onetencent package was published to the npm registry by user 't2423048543' (maintainer email t2423048543@gmail.com). It is described as 'A simple date formatting utility' but ships no such functionality; index.js only exports a hello() stub returning the package name, indicating a package created to deliver an install-time payload.
The package.json declares a postinstall hook ("node postinstall.js") that runs automatically at npm install time. The bundled postinstall.js embeds a shell command chain that performs cloud-metadata SSRF and credential/environment harvesting: it queries a public IP echo service (http://cip.cc), probes a Meituan/Sankuai internal SSRF test endpoint (https://mtsrc-test.sankuai.com/ssrf), requests AWS EC2 instance metadata credentials for the IAM role 'sandyclaw-canary-worker-role' (http://169.254.169.254/latest/meta-data/iam/security-credentials/sandyclaw-canary-worker-role), and reads Tencent Cloud metadata (http://metadata.tencentyun.com/latest/meta-data/ and http://169.254.0.23/latest/meta-data/). It then reads the installing process's environment via /proc/self/environ and exfiltrates the concatenated output, together with a directory listing of /data/, by HTTP POST to the attacker-controlled Burp Collaborator endpoint http://t5z0g2hzoydgi8mz3pfkzg8dm4svgl4a.oastify.com (paths /metadata and /data).
As shipped, the malicious command chain is stored inside postinstall.js as a JSON document (a copy of a package manifest) rather than as executable JavaScript, so the 'node postinstall.js' hook raises a syntax error and the embedded payload does not execute as-published; the intent and payload are nonetheless unambiguously malicious. A sibling package (zer0onetencent2) by the same maintainer carries an identical payload differing only in the Collaborator subdomain.
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The package is presented as 'A simple date formatting utility' with a trivial index.js exporting a hello() function, but its postinstall lifecycle script executes a shell one-liner that queries cloud instance metadata services — the AWS IMDS role credentials endpoint at 169.254.169.254 (path /latest/meta-data/iam/security-credentials/sandyclaw-canary-worker-role), the Tencent Cloud metadata service at metadata.tencentyun.com, and an additional internal SSRF endpoint — writes the responses to /tmp, reads /proc/self/environ, then POSTs the aggregated output to the hardcoded Burp Collaborator subdomain t5z0g2hzoydgi8mz3pfkzg8dm4svgl4a.oastify.com. Running on cloud build infrastructure yields short-lived IAM/STS credentials and installer environment variables to the operator of that collaborator host. The stated package purpose is a decoy for the install-time credential-harvest behavior.
{
"malicious-packages-origins": [
{
"id": "IN-MAL-2026-011001",
"import_time": "2026-08-04T21:33:13.059427548Z",
"modified_time": "2026-08-04T21:17:57Z",
"sha256": "db63abb2f3fa01d1de98c5b63e2b7cde88f35ddb18a752e670dc982fc0ddcc89",
"source": "amazon-inspector",
"versions": [
"1.0.0"
]
}
]
}[
{
"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"
}
]
{
"evidence_files": [
{
"path": "postinstall.js",
"sha256": "c629b2e94bb301b3fc4c43192e5f40a4c88fcfa8d05d4224495d4b4a3908b768",
"tlsh": "d6014ed92261b9736dc29e79e376034bb400f8472ec05b95c1d518f0898d671b255b1e"
},
{
"path": "package.json",
"sha256": "f64b7a56d6c48b30fa95cafb22515f570b3a3ebd1d45fd82089787338caa127f",
"tlsh": "2dd0a7144d105a336bd496a99da3490bbe219e1b024c7c1d23db255c83dfab3c4fe31e"
}
],
"package_integrity": [
{
"filename": "zer0onetencent-1.0.0.tgz",
"hashes": {
"sha1": "9a42071550142f23fc3faf4b2993b796b382ec51",
"sha512_sri": "sha512-1d8UlS/qCcFq6F50GnXtXBb/Q9HKHhqX1LLCAC7ae+kW8S5747t9hmYm6mnggi/Smx28golLnVmasddu6JcKRA=="
}
}
]
}
{
"domains": [
"t5z0g2hzoydgi8mz3pfkzg8dm4svgl4a.oastify.com"
],
"urls": [
"http://t5z0g2hzoydgi8mz3pfkzg8dm4svgl4a.oastify.com/metadata",
"http://t5z0g2hzoydgi8mz3pfkzg8dm4svgl4a.oastify.com/data"
]
}
"https://github.com/ossf/malicious-packages/blob/main/osv/malicious/npm/zer0onetencent/MAL-2026-10944.json"