PDF malware analysis — malicious · 038661c2d030e22f

MALICIOUS

PDF

32.7 KB Created: 2011-72-51 03:25:00 Authoring application: String.fromCharCode

MD5: 1293feb9348f43bba6dbe25b5609787f SHA-1: a425ba198d520045bed449abc2df3afdc442481b SHA-256: 038661c2d030e22fdb1a1d8e62f8c45d1b05a9bd24ae4eb910f93fc2ec93706a

114 Risk Score

Malware Insights

MITRE ATT&CK

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

The PDF file contains embedded JavaScript that utilizes String.fromCharCode and other obfuscation techniques. The script appears to construct and execute a URL, likely to download and run a secondary malicious payload. The ML classifier strongly indicates maliciousness, and the presence of JavaScript exploit cluster heuristics further supports this. The specific URL constructed by the script could not be fully resolved due to obfuscation.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

Heuristics 4

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.
JavaScript action low 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.
String.fromCharCode low PDF_FROMCHARCODE

String.fromCharCode found — used to construct payload strings dynamically. Common in benign JavaScript libraries for codepoint manipulation, so this alone is informational; weaponised use is also caught by the dedicated fromCharCode-stage and exploit-shape rules.

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0001_000.js` `e9f65aced1fa3adeebe2e4d1706cf5eec31246e60562806a54c67bf6bc154858`	pdf-javascript-stream	PDF /JS object 1 at offset 0x80B4	379 bytes

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