CVE-2023-5197 in Linux
Summary
by MITRE • 09/27/2023
A use-after-free vulnerability in the Linux kernel's netfilter: nf_tables component can be exploited to achieve local privilege escalation.
Addition and removal of rules from chain bindings within the same transaction causes leads to use-after-free.
We recommend upgrading past commit f15f29fd4779be8a418b66e9d52979bb6d6c2325.
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Analysis
by VulDB Data Team • 02/14/2025
The vulnerability identified as CVE-2023-5197 represents a critical use-after-free condition within the Linux kernel's netfilter subsystem, specifically affecting the nf_tables component that manages packet filtering rules. This flaw exists in the handling of chain bindings during rule manipulation operations, creating a scenario where memory that has been freed is still accessed by subsequent operations. The vulnerability manifests when multiple rule additions and removals occur within the same transaction context, leading to unpredictable behavior that can be exploited for privilege escalation.
The technical implementation of this vulnerability stems from improper memory management within the nf_tables subsystem where the kernel fails to properly validate the lifecycle of memory objects during concurrent rule modifications. When a transaction processes both rule additions and removals on chain bindings, the system may free memory structures while other references to those structures still exist in the call stack or data structures. This creates a race condition scenario where freed memory can be reallocated and accessed, potentially allowing an attacker to manipulate kernel memory contents. The vulnerability aligns with CWE-416, which describes use-after-free conditions, and represents a classic example of improper resource management in kernel space operations.
The operational impact of this vulnerability is severe as it enables local privilege escalation from unprivileged user contexts to kernel-level privileges. An attacker with local access can craft malicious transactions that manipulate rule bindings in a way that triggers the use-after-free condition, potentially allowing for arbitrary code execution with kernel privileges. This capability bypasses standard security boundaries and can lead to complete system compromise. The vulnerability is particularly concerning because it requires minimal privileges to exploit and can be leveraged to establish persistent backdoors or escalate privileges to root access. The ATT&CK framework categorizes this as a privilege escalation technique under T1068, specifically targeting kernel-level vulnerabilities.
Mitigation strategies for CVE-2023-5197 focus on immediate patching of affected kernel versions, with the recommended fix being the upgrade past the commit reference f15f29fd4779be8a418b66e9d52979bb6d6c2325. System administrators should prioritize updating kernel packages to versions containing the memory management fixes implemented in the patch, which properly handle the lifecycle of chain binding objects during transaction processing. Additionally, organizations should implement monitoring for suspicious rule manipulation patterns and consider restricting local user access to netfilter operations where possible. The patch addresses the core issue by ensuring proper reference counting and memory deallocation sequences, preventing the conditions that lead to the use-after-free scenario. Regular kernel updates and security assessments remain crucial for maintaining protection against similar vulnerabilities in the netfilter subsystem.