PDF malware analysis — malicious · 9a843444f9debb9f

MALICIOUS

PDF

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

MD5: 4f23a1d421d6c8933baf25f12a4bd4a7 SHA-1: c0fb7fe5b805f96d16d4c6e91d12a3c4f6c3f203 SHA-256: 9a843444f9debb9f2b14ff8462121d87638b5ea1fcdc67be304c42ff356893a9

64 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 Command and Scripting Interpreter: PowerShell

The PDF file contains embedded JavaScript, identified by the PDF_JAVASCRIPT and PDF_JS heuristics. The PDF_METADATA_EVAL_STAGER heuristic indicates that this JavaScript is used to decode and execute further code, likely from within the PDF's metadata. The String.fromCharCode heuristic further supports the obfuscation technique used by the script. The embedded JavaScript file, 'javascript_obj0001_000.js', is the primary artifact. The script's purpose is to act as a stager, downloading and executing a second-stage payload.

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` `e659dd4164c633264e07747b40c24a288311f979841d32b48bc9e55bb9a0a7ef`	pdf-javascript-stream	PDF /JS object 1 at offset 0x6272	526 bytes

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