CVE-2023-52556 in OpenBSD
Summary
by MITRE • 03/01/2024
In OpenBSD 7.4 before errata 009, a race condition between pf(4)'s processing of packets and expiration of packet states may cause a kernel panic.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 11/14/2024
The vulnerability identified as CVE-2023-52556 represents a critical race condition within the OpenBSD packet filter implementation known as pf(4). This flaw exists specifically in OpenBSD version 7.4 prior to errata 009, where the interaction between packet processing and state expiration creates a scenario that can lead to system-wide kernel panics. The race condition manifests when multiple threads or processes attempt to access and modify packet state information simultaneously, creating a timing window where the kernel's internal state management becomes inconsistent.
The technical root cause of this vulnerability stems from insufficient synchronization mechanisms within the pf(4) subsystem. When packets are being processed by the firewall and simultaneously their associated states are being expired or cleaned up, the kernel's state management code fails to properly coordinate these competing operations. This race condition falls under the category of CWE-362, which specifically addresses race conditions in concurrent programming environments. The flaw demonstrates poor handling of shared resources and inadequate mutual exclusion controls that are fundamental requirements for secure multi-threaded kernel operations.
The operational impact of this vulnerability is severe as it can result in complete system crashes through kernel panics, effectively causing a denial of service condition for the affected OpenBSD systems. Attackers who can trigger this race condition may exploit it to perform persistent denial of service attacks against network services protected by pf(4) firewalls. The vulnerability particularly affects systems that rely heavily on packet filtering and stateful inspection, making it especially dangerous for network infrastructure devices, firewalls, and servers that process high volumes of network traffic. This weakness creates an attack surface where malicious actors can potentially destabilize entire network segments or individual systems.
Mitigation strategies for CVE-2023-52556 should prioritize applying the official errata 009 patch provided by OpenBSD, which addresses the synchronization issues within pf(4) state management. System administrators should also consider implementing monitoring solutions to detect potential exploitation attempts through unusual packet processing patterns or state expiration behaviors. The fix typically involves introducing proper locking mechanisms and ensuring atomic operations when accessing shared packet state information. Organizations should also review their pf(4) configuration to minimize the complexity of state tracking and reduce the likelihood of triggering race conditions. This vulnerability aligns with ATT&CK technique T1499.004, which covers network denial of service attacks, and demonstrates how kernel-level race conditions can be leveraged to create persistent system instability.