PDF malware analysis — malicious · b3bd86d63c9c6528

MALICIOUS

PDF

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

MD5: ab94ac444f80342156b73b9aee86b49a SHA-1: e4cb7f8e0652aac11cc706a24d7d04c05bb506c2 SHA-256: b3bd86d63c9c6528e680768994c3c7c6b7fed199a10da9057c2e3351e5df1ea2

94 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell

The PDF file contains JavaScript embedded within its metadata, indicated by multiple heuristic firings including 'PDF_METADATA_EVAL_STAGER'. This JavaScript is likely used as a stager to decode and execute a malicious payload. The use of String.fromCharCode further suggests obfuscation techniques common in PDF-based malware delivery. No specific family could be identified, but the delivery mechanism is clear.

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` `2fbb15248728d3dda10b94c8221140f44f9094e1b96f25a9a20aa95d8c0e3cd4`	pdf-javascript-stream	PDF /JS object 1 at offset 0x625F	459 bytes

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