PDF malware analysis — malicious · c37223b6ff95a762

MALICIOUS

PDF

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

MD5: 83150aee7ceac807e6ed9c708febfdc2 SHA-1: 421f07949c8565b2feb34348787b4e2e2615d5c9 SHA-256: c37223b6ff95a762807b9dc6a9968a3e29ecfe8d5e6ef193b96f0df932af3a72

64 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 Command and Scripting Interpreter: PowerShell

The PDF file contains embedded JavaScript, identified by heuristics like PDF_JAVASCRIPT and PDF_JS. The PDF_METADATA_EVAL_STAGER heuristic indicates that JavaScript is used within the PDF's metadata to decode and execute code. The presence of String.fromCharCode further suggests obfuscation techniques common in malicious PDFs. The embedded JavaScript file, javascript_obj0001_000.js, is the primary artifact, likely responsible for downloading and executing a second-stage payload.

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` `988b1a2b3427feac56fb74329bcd1935618fffeb07fb5c5ea22181289cc0b161`	pdf-javascript-stream	PDF /JS object 1 at offset 0x61A3	449 bytes

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