CVE-2011-4594 in Linux
Summary
by MITRE
The __sys_sendmsg function in net/socket.c in the Linux kernel before 3.1 allows local users to cause a denial of service (system crash) via crafted use of the sendmmsg system call, leading to an incorrect pointer dereference.
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Analysis
by VulDB Data Team • 03/21/2021
The vulnerability identified as CVE-2011-4594 represents a critical kernel-level flaw in the Linux operating system that enables local privilege escalation and system instability through improper handling of socket messaging operations. This issue resides within the __sys_sendmsg function located in the net/socket.c file of the kernel source code, affecting versions prior to 3.1. The vulnerability manifests when local users execute crafted sequences involving the sendmmsg system call, which triggers an incorrect pointer dereference that ultimately results in system crashes or complete system hangs. The flaw demonstrates characteristics consistent with CWE-476, which identifies null pointer dereference conditions as a common source of system instability and potential exploitation vectors. From an operational security perspective, this vulnerability poses significant risks to system availability and integrity, as local attackers can leverage it to disrupt normal system operations without requiring elevated privileges, making it particularly dangerous in multi-user environments where system stability is paramount.
The technical exploitation of this vulnerability occurs through the manipulation of the sendmmsg system call interface, which allows applications to send multiple messages through a socket in a single system call operation. When the kernel processes these requests through the __sys_sendmsg function, it fails to properly validate or handle certain pointer parameters that are passed during the message transmission process. This incorrect pointer handling leads to a scenario where the kernel attempts to access memory locations that are either invalid or unauthorized, resulting in immediate system termination or kernel panic conditions. The vulnerability's impact extends beyond simple denial of service as it represents a fundamental breakdown in kernel memory management and input validation mechanisms, creating opportunities for more sophisticated attacks that could potentially bypass security controls. The flaw operates at the kernel level where the distinction between legitimate system operations and malicious input becomes blurred, as the kernel's own validation routines fail to prevent the execution path that leads to the pointer dereference error.
Security implications of CVE-2011-4594 extend to multiple operational domains including system availability, integrity, and reliability within enterprise and infrastructure environments. Organizations running affected Linux kernel versions face potential disruptions to critical services, particularly in environments where system uptime is essential for business operations. The vulnerability's local nature means that any user with access to the system can potentially exploit it, making it particularly concerning for multi-tenant environments or systems with shared user accounts. From an attacker's perspective, this vulnerability aligns with ATT&CK technique T1068, which involves local privilege escalation through kernel vulnerabilities, and demonstrates the broader category of privilege escalation attacks that target kernel-level flaws. The instability caused by this vulnerability can also mask other security issues or create opportunities for additional exploitation attempts, as system administrators may be focused on recovery rather than investigating potential secondary compromises. Network administrators must consider the implications of this vulnerability when planning system updates and patch management strategies, particularly in environments where immediate kernel updates may not be feasible due to compatibility or operational constraints.
Mitigation strategies for CVE-2011-4594 primarily focus on kernel version upgrades to 3.1 or later, which contain the necessary patches to address the pointer dereference issue in the __sys_sendmsg function. System administrators should prioritize the deployment of updated kernel versions across all affected systems, implementing a phased approach that includes testing in controlled environments before widespread deployment. Additional defensive measures include implementing strict access controls and monitoring for unusual system behavior that might indicate exploitation attempts, though these measures provide limited protection against the actual vulnerability. Organizations should also consider implementing kernel hardening techniques such as stack canaries, address space layout randomization, and kernel module signing to reduce the overall attack surface. The vulnerability's classification under CWE-476 highlights the importance of robust input validation and pointer management within kernel code, making it essential for system administrators to monitor for similar patterns in other kernel subsystems. Regular security assessments and vulnerability scanning should include checks for this specific vulnerability, particularly in legacy systems that may not receive regular kernel updates. The remediation process should also involve comprehensive testing to ensure that patch deployment does not introduce compatibility issues with existing applications or system configurations.