Bypassing Windows User Account Control: Using Character Editor for Privilege Escalation
A sophisticated new technique has emerged that exploits the Windows Private Character Editor to bypass User Account Control (UAC) and achieve privilege escalation without user intervention, raising significant concerns for system administrators worldwide. The attack, disclosed by Matan Bahar, leverages eudcedit.exe, Microsoft’s built-in Private Character Editor located in C:WindowsSystem32. Originally designed to create and edit End-User Defined Characters (EUDC), this utility allows users to create personalised glyphs mapped to Unicode code points for use in documents and applications. However, security researchers have discovered that this seemingly benign tool can be weaponised to bypass Windows’ primary security gatekeeper.
The vulnerability arises from critical configurations embedded within eudcedit.exe’s application manifest. Two specific metadata tags create a significant security loophole: one instructs Windows to run the binary with full administrative privileges, while the other enables automatic elevation without UAC prompts for trusted binaries executed by users in the Administrators group. This combination proves particularly dangerous. When UAC is configured with permissive settings, such as “Elevate without prompting,” Windows automatically elevates eudcedit.exe from Medium to High integrity without displaying any security warnings. The attack unfolds through a carefully crafted sequence that exploits the application’s file handling mechanisms, allowing attackers to manipulate the elevated eudcedit.exe process to execute arbitrary commands, such as spawning a high-privilege PowerShell session. This technique’s simplicity and effectiveness make it a significant concern for enterprise security teams.
Categories: Cybersecurity, Privilege Escalation, Windows Vulnerabilities
Tags: Windows, Private Character Editor, UAC, Privilege Escalation, eudcedit.exe, Security Vulnerability, File Handling, PowerShell, Integrity Level, Enterprise Security