PDF malware analysis — malicious · f2a7b22815def37d

MALICIOUS

PDF

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

MD5: 4293a85e6d801e9356d716001e8399f1 SHA-1: 131e50b345e3d7b8009f963c8a74d495c0c03571 SHA-256: f2a7b22815def37d03bc53dd47cf801be6b4c51adedd9caf6e8712f46fcdc7fc

64 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 Command and Scripting Interpreter: PowerShell

The PDF file contains embedded JavaScript, identified by heuristics such as PDF_JAVASCRIPT and PDF_JS. The PDF_METADATA_EVAL_STAGER heuristic indicates that this JavaScript is used to decode and execute a payload, likely leveraging the String.fromCharCode function as suggested by the PDF_FROMCHARCODE firing. The exact nature of the payload is not discernible from the provided evidence, but the technique suggests a downloader or stager.

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` `63fe3d3af1b50a655c3512fddc1094f2e98083fc18f7854049016f69aab26b0a`	pdf-javascript-stream	PDF /JS object 1 at offset 0x6192	528 bytes

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