PDF malware analysis — malicious · 452a15baec170fb4

MALICIOUS

PDF

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

MD5: 5da9a73325255f5f6c96018dcf53a85c SHA-1: 1cabb3f46035eba1cc96647f25173c2a65d256f2 SHA-256: 452a15baec170fb40067ddf51fc91bfbd16d15f8a665df1404eab25e95283b95

64 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 Command and Scripting Interpreter: PowerShell T1059.003 Command and Scripting Interpreter: Windows Command Shell T1059.007 Command and Scripting Interpreter: JavaScript/TypeScript

The PDF file contains embedded JavaScript, identified by multiple heuristics including 'PDF_JAVASCRIPT', 'PDF_JS', and 'PDF_METADATA_EVAL_STAGER'. The JavaScript is obfuscated using 'String.fromCharCode', a common technique for evading static analysis. This script is likely responsible for decoding and executing a second-stage payload. The presence of these indicators suggests a malicious document designed to deliver further malware.

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` `e39174b8e401de36f0d4b9ce9e91ecb63b98d12b90a3747f9bcbcf227852bdb5`	pdf-javascript-stream	PDF /JS object 1 at offset 0x6227	457 bytes

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