PDF malware analysis — malicious · 1e4b6e6e8e09ecc0

MALICIOUS

PDF

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

MD5: bd231480f8772eb8e4a31a8cee9520e5 SHA-1: 1668cd555d3ed5625cfcdcd567e365112c778f42 SHA-256: 1e4b6e6e8e09ecc022ee272e2f02179705db2eca744c99858efdd4f88b2cb61f

94 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell

This PDF file was flagged as malicious by an ML classifier and exhibits high-confidence heuristic firings for a JavaScript eval stager within its metadata. The presence of JavaScript, specifically using String.fromCharCode, indicates an attempt to obfuscate and execute code. The primary function appears to be a stager, likely designed to download and execute a secondary payload, though the specific URL or payload is not directly extractable from the provided metadata and script fragments.

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` `a559b662f5bc27446f78dc7a167baa3e955cac45217888b147f0e20f080819bf`	pdf-javascript-stream	PDF /JS object 1 at offset 0x631F	520 bytes

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