CVE-2022-23091 in FreeBSD
Summary
by MITRE • 02/15/2024
A particular case of memory sharing is mishandled in the virtual memory system. This is very similar to SA-21:08.vm, but with a different root cause.
An unprivileged local user process can maintain a mapping of a page after it is freed, allowing that process to read private data belonging to other processes or the kernel.
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Analysis
by VulDB Data Team • 10/29/2024
This vulnerability represents a critical memory safety issue within the virtual memory management subsystem of operating systems. The flaw occurs when the kernel fails to properly handle specific cases of memory sharing, creating a scenario where freed memory pages remain accessible to user processes. Unlike similar vulnerabilities such as SA-21:08.vm, this instance has a distinct root cause that specifically targets the memory management mechanisms responsible for tracking page mappings and their lifecycle. The vulnerability exploits a race condition or improper memory deallocation logic that allows processes to retain references to pages that should have been released back to the system.
The technical implementation of this vulnerability enables an unprivileged local user to maintain active mappings of memory pages that have already been freed by the system. This creates a persistent access vector that can be exploited to read sensitive data from other processes or even from kernel memory spaces. The memory sharing mishandling occurs at the virtual memory management layer where page table entries or reference counters are not properly updated when pages transition from active to freed states. This allows the malicious process to continue accessing previously allocated memory regions, potentially exposing confidential information, credentials, or system internals that should have been securely purged.
The operational impact of this vulnerability is severe as it fundamentally undermines the memory isolation guarantees that operating systems rely on to protect process privacy and system integrity. An attacker can leverage this weakness to perform information disclosure attacks, potentially accessing data belonging to other running processes, including sensitive system components or user applications. The vulnerability affects the core memory management functionality and can be exploited without requiring elevated privileges, making it particularly dangerous in multi-tenant environments or systems where multiple users share the same physical hardware. This type of vulnerability directly violates the principle of least privilege and can lead to complete system compromise if combined with other exploitation techniques.
Mitigation strategies should focus on strengthening the virtual memory management subsystem through proper page deallocation procedures and enhanced reference counting mechanisms. System administrators should implement immediate patches provided by operating system vendors to address the specific memory management flaw. Additional defensive measures include enabling kernel memory protection features such as address space layout randomization, kernel address space layout randomization, and memory access controls that prevent unauthorized page mapping retention. The vulnerability aligns with CWE-129 and CWE-131 categories related to improper input validation and memory management errors, and can be categorized under ATT&CK technique T1059 for privilege escalation and T1003 for credential access. Regular security auditing of memory management components and monitoring for anomalous memory access patterns should be implemented as part of comprehensive security operations to detect potential exploitation attempts.