PDF malware analysis — malicious · 5421ad5e85872b6f

MALICIOUS

PDF

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

MD5: 935577354674163948ef8678a6115b99 SHA-1: 1b3b006345a5e9b2d4aa219a0bd137be1d164c80 SHA-256: 5421ad5e85872b6f1b66d4c5ef045bfeafdd434eea1a03e04172e6fed955f35d

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 a payload, likely leveraging 'String.fromCharCode' as suggested by another heuristic. The primary function appears to be the execution of a second-stage payload via JavaScript. No specific family could be identified.

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` `87f89be71b2f8e8092322e3e8bc6d1f892993c0072a14424fc4b023e1d29838e`	pdf-javascript-stream	PDF /JS object 1 at offset 0x624D	462 bytes

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