PDF malware analysis — malicious · b4f2f56903114a98

MALICIOUS

PDF

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

MD5: 5aa97d1ca124dc4bcae5216c309d0a58 SHA-1: bf227350f91a7292f46dcd4466ba99509e0934af SHA-256: b4f2f56903114a98814fda2278b669cfb9c91246f0827eaa3b8c5258463e71be

64 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 Command and Scripting Interpreter: PowerShell

The PDF file contains embedded JavaScript within its metadata, identified by the 'PDF_METADATA_EVAL_STAGER' heuristic. This JavaScript, utilizing 'String.fromCharCode', is designed to decode and execute a secondary payload. The presence of JavaScript actions and streams further supports this. The exact nature of the payload is not discernible from the provided evidence, but the obfuscated JavaScript points to 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` `c1a86b6cb8b78e4d16d1c4dc7b95ab2b6d2800dc1574407f19980d645f298db4`	pdf-javascript-stream	PDF /JS object 1 at offset 0x62EF	520 bytes

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