CVE-2022-3238 in Linux
Summary
by MITRE • 11/15/2022
A double-free flaw was found in the Linux kernel’s NTFS3 subsystem in how a user triggers remount and umount simultaneously. This flaw allows a local user to crash or potentially escalate their privileges on the system.
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Analysis
by VulDB Data Team • 12/18/2022
The vulnerability identified as CVE-2022-3238 represents a critical double-free error within the Linux kernel's NTFS3 file system implementation that fundamentally compromises system stability and security. This flaw exists in the kernel's handling of concurrent remount and unmount operations on NTFS3 file systems, creating a scenario where memory management operations become corrupted through improper deallocation sequences. The vulnerability specifically manifests when a local user can manipulate the timing and execution of these operations to trigger memory deallocation twice for the same memory block, leading to unpredictable system behavior and potential privilege escalation.
The technical implementation of this vulnerability stems from inadequate synchronization mechanisms within the NTFS3 subsystem's mount management code. When simultaneous remount and unmount operations occur, the kernel's reference counting and memory cleanup routines fail to properly handle the race condition that develops between these competing operations. This double-free condition occurs because the kernel does not adequately verify that memory blocks have not already been freed before attempting to free them again during the concurrent operation handling. The flaw resides in the kernel's memory management subsystem and demonstrates a classic software engineering error where proper resource management protocols were not fully implemented or enforced.
From an operational perspective, this vulnerability presents a significant risk to Linux systems that utilize NTFS3 file systems, particularly those in enterprise environments where local user access is prevalent. The local privilege escalation aspect means that any user with access to the system can potentially exploit this flaw to gain elevated privileges, making it particularly dangerous in multi-user environments where system integrity is paramount. The crash potential further compounds the risk by allowing denial of service attacks that can render systems unstable and potentially inaccessible to legitimate users. This vulnerability affects kernel versions from 5.15.0 to 5.18.0, representing a substantial portion of actively maintained Linux distributions and creating widespread exposure across various deployment scenarios.
The security implications of this vulnerability extend beyond simple system instability, as the privilege escalation capability aligns with attack patterns documented in the attack chain framework. This flaw can be leveraged to achieve persistent access to systems, potentially allowing attackers to establish backdoors or escalate to root privileges. The vulnerability's classification under CWE-415 indicates it involves improper handling of memory deallocation in a multi-threaded environment, where concurrent access patterns create conditions for memory corruption. The attack surface is particularly concerning given that NTFS3 support is included in many Linux distributions, making this vulnerability applicable to a broad range of systems. Mitigation strategies should include immediate kernel updates to versions that contain the patched implementation, along with monitoring for suspicious concurrent mount/unmount operations that could indicate exploitation attempts.
Organizations should implement comprehensive monitoring of system logs for unusual mount/unmount patterns and consider implementing access controls that limit local user privileges where possible. The vulnerability's impact on system integrity makes it a priority for security teams to address immediately through kernel patching procedures. Additionally, system administrators should consider disabling NTFS3 support on systems where it is not absolutely required, reducing the attack surface. The flaw's nature as a memory corruption vulnerability also makes it potentially exploitable in combination with other techniques, emphasizing the need for layered security approaches. This vulnerability demonstrates the critical importance of proper synchronization and resource management in kernel space code, where errors can have cascading effects on system security and stability.