PDF malware analysis — malicious · 3da7f58e945b1679

MALICIOUS

PDF

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

MD5: b2595cf049a0e48717897b9c371f2b00 SHA-1: fd8b54b39f84d30b1597ace13fcaec0b1edd5efa SHA-256: 3da7f58e945b1679cf158aa9a5dbfbe349de74bedbf7fb7c55748f7b119e4f7a

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 as a stager, likely to decode and execute further malicious code. The ML classifier strongly flags this PDF as malicious. No specific family could be identified, but the technique suggests a downloader or initial access stage.

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` `d1aa6c77ab61ef027e1c35775ccab5b7bc8c4353ab9515c5d764a0772f55ed64`	pdf-javascript-stream	PDF /JS object 1 at offset 0x62C3	527 bytes

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