PDF malware analysis — malicious · 3186ecd06d826e4e

MALICIOUS

PDF

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

MD5: 9b24c6c20de64289712c49d6aabd268c SHA-1: f3026e17a6a4123227251a076db4a5569eb5f547 SHA-256: 3186ecd06d826e4ec5a33983c71892f9044808b203f7860192e69e016f690e22

94 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell

The PDF file contains embedded JavaScript, identified by heuristics such as '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 code. The presence of 'String.fromCharCode' further suggests obfuscation techniques common in malicious JavaScript. The ML classifier strongly flags this PDF as malicious. The embedded JavaScript is likely responsible for downloading and executing a second-stage payload.

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` `a3e376505c9b18e741dd3937b37023197d8d69e86e0d0bbae24aa026d9232427`	pdf-javascript-stream	PDF /JS object 1 at offset 0x62D4	520 bytes

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