PDF malware analysis — malicious · d021a7b99262f379

MALICIOUS

PDF

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

MD5: 9e9b29972979ce72b33f07417fa8312d SHA-1: 38ec20457d4b41841a4c46523e2299827b4afe44 SHA-256: d021a7b99262f37976357a215358796b2d86fe9238a319baa61099b77744b816

94 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell

This PDF file contains embedded JavaScript, identified by the 'PDF_JAVASCRIPT' and 'PDF_JS' heuristics. The 'PDF_METADATA_EVAL_STAGER' heuristic indicates that the JavaScript is used to decode and execute a payload, likely leveraging 'String.fromCharCode' as seen in the document body and heuristics. The ML classifier strongly suggests maliciousness. Due to the obfuscated nature of the JavaScript and lack of specific indicators, the family is unknown, but the attack pattern involves a stager within the PDF metadata.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

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` `b731bb72ac44f70f83723051b9dd3fd111233a6a187d64f184ef495aa3f95ee5`	pdf-javascript-stream	PDF /JS object 1 at offset 0x6249	451 bytes

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