PDF malware analysis — malicious · da685321f85fa5d2

MALICIOUS

PDF

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

MD5: 5f96e380eaadec994537575df71a974f SHA-1: b9a2a1ac95de4b45ba143a2e9885a0cad9b353a9 SHA-256: da685321f85fa5d2a4843a8f8f45ce659a7c811b2073a954fb008f723e2b8d24

64 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell

The PDF file contains embedded JavaScript, indicated by multiple heuristic firings including 'PDF_JAVASCRIPT', 'PDF_JS', and 'PDF_METADATA_EVAL_STAGER'. The 'String.fromCharCode' function is used, suggesting obfuscation of JavaScript code. The primary intent appears to be executing this JavaScript, which is likely designed to download and execute a secondary payload. No specific family could be identified due to the generic nature of the obfuscation.

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` `92a2138c67ae2921331c92a92bcb02750a24e3bbd9619aa2187198acea294dcb`	pdf-javascript-stream	PDF /JS object 1 at offset 0x622C	457 bytes

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