PDF malware analysis — malicious · 3d138c310abd9c7c

MALICIOUS

PDF

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

MD5: ac2942357fd557c3d43a65a22a838ed8 SHA-1: 1c477cd40c4994239ec6fad33cc137c4a8125040 SHA-256: 3d138c310abd9c7c33cf974b8a8b082fb7c7748d09c8989acc03d22ac103ef5b

94 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1566.001 Spearphishing Attachment T1204.002 Malicious File

The PDF file contains embedded JavaScript, identified by heuristics such as 'PDF_JAVASCRIPT' and 'PDF_JS'. The 'PDF_METADATA_EVAL_STAGER' heuristic indicates that JavaScript within the PDF's metadata is used to decode and execute a payload. The presence of 'String.fromCharCode' further suggests obfuscation techniques common in JavaScript-based malware. The ML classifier strongly flags this PDF as malicious. The primary attack pattern involves luring the user into opening a malicious PDF which then executes embedded JavaScript.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

Heuristics 4

PDF metadata JavaScript eval stager high PDF_METADATA_EVAL_STAGER

PDF JavaScript reads document metadata fields such as title, subject, or producer, decodes character data with parseInt/String.fromCharCode style helpers, and evals the recovered stage. This is a high-signal exploit-kit staging pattern.
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` `aceba1b0a41ed330d7a61c2786eb91652f154dcacb3fc36a212102d8ea8bc2ac`	pdf-javascript-stream	PDF /JS object 1 at offset 0x6260	515 bytes

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