PDF malware analysis — malicious · c7dfc70b025c0b73

MALICIOUS

PDF

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

MD5: c31dd5da2bb659ed24f83e598c9cf101 SHA-1: 6519ba66bb4e6374bb6518d7c7c4bd00a838b5fc SHA-256: c7dfc70b025c0b7372296d7668916c736bcd3a36f5861bd94f65ac590a06c37e

94 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 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 within the PDF's metadata is used to decode and execute further code. The use of 'String.fromCharCode' in the document body and metadata suggests obfuscation techniques common in malware delivery. The ML classifier strongly indicates maliciousness. The primary attack pattern involves leveraging JavaScript for initial execution, likely as a stager for downloading additional malicious content.

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` `6e8f5bff284e671b57a6792f633b8e3f747b8047995b1a77b266c286068b31a8`	pdf-javascript-stream	PDF /JS object 1 at offset 0x62AD	517 bytes

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