PDF malware analysis — malicious · 1ac494d7a1bbd18c

MALICIOUS

PDF

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

MD5: b1234fec46eebc80442a0e19557121af SHA-1: ebcd1c91a669ffd6aaefe664a18af578eb04eb6d SHA-256: 1ac494d7a1bbd18c937307d48d7a0bdbb1734eccefe9ddf53679d095246d2884

94 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell

The PDF sample contains embedded JavaScript within its metadata, which is a common technique for obfuscating malicious code execution. The heuristics indicate the use of String.fromCharCode and an eval stager, suggesting the script is designed to decode and execute a payload. While the exact payload is not visible, this pattern strongly suggests a downloader or dropper functionality. The ML classifier also confirms the malicious nature of the file.

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` `aa3e2d75f07781abff14fee77ded5124e0b28ae8311246b15e426b227315c4de`	pdf-javascript-stream	PDF /JS object 1 at offset 0x631A	520 bytes

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