CVE-2004-0114 in FreeBSD
Summary
by MITRE
The shmat system call in the System V Shared Memory interface for FreeBSD 5.2 and earlier, NetBSD 1.3 and earlier, and OpenBSD 2.6 and earlier, does not properly decrement a shared memory segment s reference count when the vm_map_find function fails, which could allow local users to gain read or write access to a portion of kernel memory and gain privileges.
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Analysis
by VulDB Data Team • 08/14/2024
The vulnerability described in CVE-2004-0114 represents a critical memory management flaw within the System V Shared Memory implementation across multiple open source operating systems. This issue specifically targets the shmat system call which is responsible for attaching shared memory segments to a process address space. The flaw manifests when the vm_map_find function encounters a failure during the memory mapping process, leaving the shared memory segment reference count improperly decremented. This improper reference counting mechanism creates a scenario where kernel memory regions remain accessible beyond their intended lifecycle, fundamentally compromising the memory isolation principles that protect operating system kernels from user-space interference.
The technical exploitation of this vulnerability leverages the improper reference count handling within the shared memory subsystem to create a race condition or memory access anomaly. When vm_map_find fails, the system should properly clean up the shared memory segment reference count to ensure the segment is properly deallocated or marked for reuse. However, the failure to decrement this counter means that the kernel continues to maintain references to memory regions that should have been released, creating potential pathways for local privilege escalation. This flaw directly relates to CWE-129, which addresses improper handling of reference counts in memory management systems, and can be categorized under CWE-264 as it involves improper privilege management through memory access control mechanisms.
The operational impact of this vulnerability extends beyond simple memory corruption, as it provides local attackers with the capability to read and write kernel memory directly. This access enables privilege escalation attacks where malicious users can manipulate kernel data structures, potentially gaining root access to compromised systems. The vulnerability affects multiple operating systems including FreeBSD 5.2 and earlier versions, NetBSD 1.3 and earlier, and OpenBSD 2.6 and earlier, indicating a widespread issue within the Unix-like operating system family. Attackers could exploit this to access sensitive kernel information, modify critical system data, or even inject malicious code into kernel space, making this a particularly dangerous vulnerability for systems running these older versions.
Mitigation strategies for CVE-2004-0114 primarily focus on immediate system updates and patches provided by the respective operating system vendors. System administrators should prioritize upgrading to patched versions of FreeBSD, NetBSD, and OpenBSD that address the improper reference counting in shared memory management. Additionally, implementing proper access controls and limiting local user privileges can reduce the potential impact of exploitation attempts. The vulnerability demonstrates the importance of proper memory management practices and highlights the critical need for thorough testing of system call implementations, particularly those involving kernel memory allocation and deallocation. Security monitoring should include detection of unusual shared memory access patterns, and system administrators should consider implementing kernel hardening measures such as address space layout randomization and stack canaries to further reduce exploitability. This vulnerability serves as a reminder of the critical importance of maintaining current system versions and the potential consequences of running outdated operating system releases that may contain unpatched memory management flaws.