CVE-2023-1476 in Linux
Summary
by MITRE • 11/03/2023
A use-after-free flaw was found in the Linux kernel’s mm/mremap memory address space accounting source code. This issue occurs due to a race condition between rmap walk and mremap, allowing a local user to crash the system or potentially escalate their privileges on the system.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 11/30/2023
The vulnerability identified as CVE-2023-1476 represents a critical use-after-free flaw within the Linux kernel's memory management subsystem, specifically in the mm/mremap component responsible for memory address space accounting. This flaw manifests as a race condition between the reverse mapping walk process and the mremap operation, creating a window where memory objects can be accessed after they have been freed, potentially leading to system instability or privilege escalation. The vulnerability resides in the kernel's memory management code that handles memory region remapping operations, making it particularly dangerous as it operates at the core level of system memory handling.
The technical implementation of this vulnerability exploits a timing issue where multiple kernel threads can simultaneously access the same memory structures without proper synchronization mechanisms. During an mremap operation, when memory regions are being moved or resized, the reverse mapping walk process that tracks memory mappings can interfere with the operation, creating a scenario where freed memory objects remain accessible to subsequent operations. This race condition stems from inadequate locking mechanisms and memory management synchronization within the kernel's memory accounting code, allowing for potential memory corruption that can be exploited by local attackers.
The operational impact of CVE-2023-1476 extends beyond simple system crashes to potentially enable privilege escalation attacks, making it a significant concern for system administrators and security professionals. A local attacker with minimal privileges can exploit this vulnerability to either cause a denial of service through system crashes or potentially escalate their privileges to gain root access, depending on the specific conditions and system configuration. The vulnerability affects all Linux kernel versions that implement the mremap functionality, particularly those running on systems with memory-intensive applications or those utilizing memory mapping operations frequently.
Mitigation strategies for CVE-2023-1476 should prioritize immediate kernel updates from vendors such as Red Hat, Ubuntu, and other distribution maintainers who have released patches addressing this specific race condition. System administrators should implement comprehensive monitoring to detect anomalous memory access patterns or potential exploitation attempts, as the vulnerability may manifest through subtle memory corruption rather than obvious crash symptoms. The fix typically involves implementing proper locking mechanisms and synchronization between the mremap operation and reverse mapping walk processes, ensuring that memory objects are not accessed after being freed. Additionally, organizations should consider implementing runtime protections such as kernel address space layout randomization and memory protection mechanisms to reduce the effectiveness of potential exploitation attempts, while also conducting thorough vulnerability assessments to identify systems potentially affected by this memory management flaw. This vulnerability aligns with CWE-416 which addresses use-after-free conditions and represents a significant concern under the ATT&CK framework's privilege escalation techniques, particularly those involving kernel-level exploitation methods.