CVE-2022-1966 in Linux
Summary
by MITRE • 06/06/2022
A use-after-free vulnerability was found in the Linux kernel's Netfilter subsystem in net/netfilter/nf_tables_api.c. This flaw allows a local attacker with user access to cause a privilege escalation issue.
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Analysis
by VulDB Data Team • 10/15/2024
The vulnerability identified as CVE-2022-1966 represents a critical use-after-free condition within the Linux kernel's Netfilter subsystem, specifically within the nf_tables_api.c component. This flaw exists in the kernel's packet filtering and network traffic management framework that handles netfilter table operations. The vulnerability arises from improper memory management during the processing of netfilter table operations, creating a scenario where freed memory locations can be accessed or reused by subsequent operations. The issue is particularly concerning because it affects the core networking infrastructure of Linux systems, making it a prime target for exploitation by malicious actors who seek to elevate their privileges from user-level access to kernel-level privileges.
The technical implementation of this vulnerability stems from the improper handling of reference counting and memory deallocation within the netfilter subsystem's table management functions. When certain netfilter table operations are performed, the kernel allocates memory structures to manage table entries and their associated data. However, due to a race condition or improper synchronization during the deletion and reuse of these structures, the kernel may attempt to access memory that has already been freed. This use-after-free condition creates a memory corruption scenario that can be exploited to execute arbitrary code within kernel space. The vulnerability is classified as a CWE-416: Use After Free, which directly maps to the fundamental flaw in memory management. The attack vector requires local user access, meaning an attacker must already have user-level privileges on the target system, but the successful exploitation results in privilege escalation to kernel-level access.
The operational impact of CVE-2022-1966 extends beyond simple privilege escalation, as it fundamentally undermines the security model of Linux systems by allowing unprivileged users to gain root-level access. This vulnerability affects all Linux kernel versions that include the affected netfilter subsystem code, making it particularly widespread across enterprise and consumer environments. The exploitation of this vulnerability can lead to complete system compromise, enabling attackers to install persistent backdoors, modify system files, access sensitive data, or establish covert communication channels. From an attacker's perspective, this vulnerability aligns with the MITRE ATT&CK framework's privilege escalation techniques, specifically targeting the 'Exploitation for Privilege Escalation' tactic. The vulnerability also falls under the 'Kernel Module Loading' and 'System Service Manipulation' techniques as attackers can leverage the elevated privileges to manipulate system services and load malicious kernel modules. The impact is severe because it allows attackers to bypass traditional security controls and gain persistent access to systems without requiring additional attack vectors.
Mitigation strategies for CVE-2022-1966 primarily focus on applying kernel updates and patches provided by Linux distribution vendors. System administrators should immediately deploy the latest kernel versions that contain the fix for this vulnerability, which typically involves proper memory management and reference counting corrections within the netfilter subsystem. Additionally, implementing network segmentation and access controls can limit the potential impact of exploitation, as attackers need local access to the target system. The vulnerability also highlights the importance of kernel hardening techniques, including the use of kernel address space layout randomization, stack canaries, and other exploit mitigation features. Organizations should also consider implementing monitoring solutions that can detect anomalous behavior indicative of privilege escalation attempts. The fix for this vulnerability typically involves correcting the memory deallocation sequence and ensuring proper synchronization mechanisms are in place to prevent race conditions that lead to the use-after-free condition. Regular security assessments and kernel vulnerability scanning should be part of ongoing security operations to identify and remediate similar issues before they can be exploited by malicious actors.