Microsoft Brokering File System Double Free Vulnerability: A Deep Look into CVE-2025-49693
Introduction
Privilege escalation vulnerabilities continue to pose significant threats, particularly when they affect widely used operating systems like Microsoft Windows. CVE-2025-49693, a double free vulnerability within the Microsoft Brokering File System, exemplifies this threat by enabling authenticated local attackers to escalate privileges to SYSTEM level. Given Microsoft's global presence and the critical role of Windows in enterprise environments, understanding and mitigating this vulnerability is imperative for maintaining organizational security.
Technical Information
CVE-2025-49693 arises from a double free condition (CWE-415) within the Microsoft Brokering File System, a kernel-mode driver integral to Windows' file operations and inter-process communication. The vulnerability occurs due to improper handling of memory allocation and deallocation, specifically when the same memory address is inadvertently freed multiple times. This flaw can be triggered by an authenticated attacker who submits specially crafted data to the vulnerable component, causing memory corruption.
The corrupted memory state allows attackers to overwrite critical kernel structures, including process tokens that define user privileges. By manipulating these tokens, attackers can escalate their privileges from limited user-level access to full SYSTEM-level control. This escalation effectively bypasses the security boundaries between user and kernel modes, granting attackers comprehensive control over the compromised system.
Affected systems include Windows 10 versions 1607 through 22H2, Windows 11 versions 22H2 and 24H2, and Windows Server 2022 and 2025 editions. Exploitation requires local access and valid authentication credentials, making this vulnerability particularly dangerous in environments where attackers have already established an initial foothold.
Patch Information
Microsoft has released a security update to address the double free vulnerability in the Microsoft Brokering File System, identified as CVE-2025-49693. This vulnerability could allow an authorized attacker to elevate privileges locally. The patch modifies the memory management routines within the Brokering File System to ensure that memory is freed only once, preventing the possibility of double free errors. By implementing this fix, the update eliminates the risk of memory corruption that could be exploited for privilege escalation. Users are strongly advised to apply this update promptly to secure their systems against potential attacks.
Detection Methods
Detecting vulnerabilities addressed in Microsoft's July 2025 Patch Tuesday requires a comprehensive approach, utilizing both automated tools and manual analysis to identify potential security risks effectively.
Automated Vulnerability Scanning:
Utilizing tools like Tenable's Nessus can streamline the detection process. For instance, Nessus Plugin ID 241545 is designed to identify systems missing the July 2025 security update (KB5062553). This plugin checks for the presence of specific updates and flags systems that are vulnerable due to missing patches.
Manual Verification:
While automated tools are efficient, manual verification is crucial for comprehensive security assessments. Reviewing system logs, update histories, and configuration settings can help identify discrepancies or missed updates that automated tools might overlook.
Indicators of Compromise (IoCs):
Monitoring for unusual system behavior, unexpected network traffic, or unauthorized access attempts can serve as indicators of potential exploitation. Establishing baseline system behavior and regularly reviewing logs can aid in the early detection of security incidents.
Patch Management:
Implementing a robust patch management strategy ensures that systems are updated promptly. Regularly applying security updates, such as those released in the July 2025 Patch Tuesday, mitigates the risk of exploitation.
Security Information and Event Management (SIEM):
Deploying SIEM solutions can centralize log collection and analysis, providing real-time monitoring and alerting for potential security events. This proactive approach enables swift response to detected threats.
References
Source: This report was created using AI
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