PDF malware analysis — malicious · da087e8fc2a04799

MALICIOUS

PDF

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

MD5: b63d9df8310b722191fa74126612674c SHA-1: 1791a9a129b99f691aa6290a996d236f6d080301 SHA-256: da087e8fc2a047999168e051574ba76855dcffbae38edd535b12d93fb1bd66f4

94 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell

The PDF file contains embedded JavaScript, triggered via metadata, which is a common technique for initial execution. The heuristic 'PDF_METADATA_EVAL_STAGER' strongly suggests the JavaScript is used to decode and execute further malicious code. The presence of 'String.fromCharCode' in both the document body and heuristics indicates obfuscation techniques are being used to hide the malicious payload. While no specific family is identified, the overall pattern points to a downloader or stager.

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` `2265a827cda4a7eb4ad0e51207c2f917e91f78904513b4284736245aa2a7cf46`	pdf-javascript-stream	PDF /JS object 1 at offset 0x6258	529 bytes

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