CVE-2015-2553 in Windows
Summary
by MITRE
The kernel in Microsoft Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8, Windows 8.1, Windows Server 2012 Gold and R2, Windows RT Gold and 8.1, and Windows 10 mishandles junctions during mountpoint creation, which makes it easier for local users to gain privileges by leveraging certain sandbox access, aka "Windows Mount Point Elevation of Privilege Vulnerability."
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Analysis
by VulDB Data Team • 06/15/2025
The vulnerability described in CVE-2015-2553 represents a critical privilege escalation flaw within the Windows kernel's handling of junction points during mountpoint creation processes. This issue affects a broad range of Microsoft operating systems including Windows Vista through Windows 10, making it particularly concerning from a security perspective. The vulnerability stems from improper validation and handling of junction points when the system creates mountpoints, creating opportunities for malicious actors to exploit the kernel's insufficient access controls and validation mechanisms.
The technical flaw manifests in the kernel's mountpoint creation routine where junction points are not properly validated or secured during the creation process. When a junction point is created, the system should enforce strict access controls and validate the integrity of the target path before allowing the mountpoint to be established. However, this vulnerability allows local users to manipulate the junction point creation process by leveraging specific sandbox access conditions, effectively bypassing normal security boundaries that should prevent privilege escalation. The vulnerability operates through a race condition or improper access control check that enables attackers to create malicious mountpoints that can be used to elevate privileges from standard user level to system level.
The operational impact of this vulnerability is significant as it enables local users to achieve privilege escalation without requiring remote access or complex exploitation techniques. Attackers can leverage sandbox environments or restricted user contexts to create malicious junction points that, when processed by the kernel, result in elevated privileges. This represents a classic sandbox escape scenario where the security boundaries of restricted user environments are bypassed through kernel-level manipulation. The vulnerability is particularly dangerous because it requires minimal privileges to exploit and can be combined with other techniques to create persistent access or escalate to full system control. This vulnerability has been categorized under CWE-264, which relates to Permissions, Privileges, and Access Controls, specifically addressing issues with improper access control in kernel-level operations.
The exploitation of this vulnerability aligns with several techniques documented in the ATT&CK framework, particularly under privilege escalation tactics where adversaries seek to gain higher-level permissions within a system. The vulnerability enables techniques such as "Exploitation for Privilege Escalation" and "Windows Management Instrumentation" where attackers can leverage kernel-level flaws to achieve system-level access. Security professionals should note that this vulnerability demonstrates the critical importance of kernel-level access control validation and proper handling of system resources during mountpoint creation. The issue also relates to "Sandbox Evasion" techniques where attackers bypass application sandboxing mechanisms through kernel-level manipulation.
Mitigation strategies for this vulnerability require immediate patch deployment as provided by Microsoft through their regular security updates, specifically addressing the kernel mountpoint handling routines. System administrators should implement the principle of least privilege and ensure that users have minimal necessary access rights to prevent exploitation. Additional mitigations include monitoring for suspicious mountpoint creation activities and implementing enhanced kernel integrity checking mechanisms. The vulnerability highlights the need for comprehensive security testing of kernel-level operations and proper validation of all system resource manipulations. Organizations should also consider implementing endpoint detection and response solutions that can identify anomalous mountpoint creation patterns that may indicate exploitation attempts, as this vulnerability can be used in conjunction with other attack vectors to achieve persistent system compromise.