CVE-2015-7613 in Linux
Summary
by MITRE
Race condition in the IPC object implementation in the Linux kernel through 4.2.3 allows local users to gain privileges by triggering an ipc_addid call that leads to uid and gid comparisons against uninitialized data, related to msg.c, shm.c, and util.c.
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Analysis
by VulDB Data Team • 07/17/2024
The vulnerability identified as CVE-2015-7613 represents a critical race condition within the Inter-Process Communication (IPC) object implementation of the Linux kernel version 4.2.3 and earlier. This flaw resides in the core kernel subsystem responsible for managing shared memory segments, message queues, and semaphores through the ipc_addid function call. The race condition occurs during the process of adding new IPC objects to the system, where concurrent access patterns can lead to improper initialization of critical data structures. The vulnerability specifically affects the msg.c, shm.c, and util.c source files, indicating a systemic issue within the kernel's IPC management framework rather than isolated component failure.
The technical exploitation of this vulnerability stems from the improper handling of uid and gid comparisons during IPC object creation. When multiple processes attempt to simultaneously create or access IPC objects, the race condition allows an attacker to manipulate the timing of these operations to access uninitialized memory locations. The uninitialized data contains potentially exploitable information that can be used to bypass access control mechanisms and escalate privileges from a regular user to root level access. This type of vulnerability falls under CWE-362, which specifically addresses race conditions in software systems where concurrent access to shared resources can lead to inconsistent states and security breaches.
The operational impact of CVE-2015-7613 is severe for any Linux system running vulnerable kernel versions, as it provides a local privilege escalation vector that can be exploited by unprivileged users to gain complete system control. Attackers can leverage this vulnerability to execute arbitrary code with root privileges, potentially leading to full system compromise, data exfiltration, or persistent backdoor installation. The vulnerability's presence in core kernel components means that any system utilizing shared memory segments, message queues, or semaphores is at risk, making it particularly dangerous in multi-user environments or systems with untrusted local users. The exploitability of this vulnerability aligns with ATT&CK technique T1068, which covers local privilege escalation through kernel vulnerabilities, and T1548.001, covering abuse of root or administrator privileges.
Mitigation strategies for CVE-2015-7613 primarily involve applying the official kernel patches released by the Linux kernel development team, which address the race condition through proper synchronization mechanisms and initialization of data structures. System administrators should prioritize updating to kernel versions 4.2.4 and later, where the vulnerability has been resolved through improved locking mechanisms and data validation procedures. Additionally, implementing proper access controls and limiting local user privileges can reduce the attack surface, though this does not eliminate the vulnerability itself. Monitoring for suspicious IPC object creation patterns and implementing kernel hardening measures such as stack canaries and address space layout randomization can provide additional defense in depth. The vulnerability's resolution demonstrates the importance of thorough testing and validation of concurrent access patterns in kernel subsystems, particularly those handling critical system resources and access controls.