CVE-2011-2534 in Linux
Summary
by MITRE
Buffer overflow in the clusterip_proc_write function in net/ipv4/netfilter/ipt_CLUSTERIP.c in the Linux kernel before 2.6.39 might allow local users to cause a denial of service or have unspecified other impact via a crafted write operation, related to string data that lacks a terminating \0 character.
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Analysis
by VulDB Data Team • 11/13/2021
The vulnerability described in CVE-2011-2534 represents a critical buffer overflow condition within the Linux kernel's netfilter subsystem, specifically affecting the clusterip_proc_write function in the ipt_CLUSTERIP.c file. This flaw exists in kernel versions prior to 2.6.39 and demonstrates a classic security weakness that can be exploited by local attackers to compromise system integrity and availability. The vulnerability stems from improper handling of string data within the kernel's networking components, where the absence of a proper null termination character creates an exploitable condition that can lead to memory corruption.
The technical implementation of this vulnerability occurs within the clusterip_proc_write function which processes write operations to the clusterip proc entry in the kernel's virtual file system. When local users perform crafted write operations to this interface, the function fails to properly validate or terminate string data before processing, leading to a buffer overflow condition. This type of vulnerability falls under CWE-121, which specifically addresses stack-based buffer overflow conditions, and more broadly aligns with CWE-787, representing out-of-bounds write operations. The flaw manifests when the kernel's string handling routines do not properly account for the absence of null terminators, allowing attackers to overwrite adjacent memory locations and potentially execute arbitrary code or cause system crashes.
The operational impact of CVE-2011-2534 extends beyond simple denial of service scenarios, as it provides local attackers with the potential to escalate privileges and compromise the entire system. Attackers can leverage this vulnerability to cause kernel memory corruption that may result in system panics, kernel oops, or more severe privilege escalation attacks. From an adversarial perspective, this vulnerability maps to ATT&CK technique T1068, which covers privilege escalation through kernel exploits, and T1499, covering network denial of service attacks. The vulnerability's local nature means that any user with access to the system can potentially exploit it, making it particularly dangerous in multi-user environments or when system access is not properly restricted.
Mitigation strategies for this vulnerability require immediate kernel updates to versions 2.6.39 or later where the buffer overflow has been patched. System administrators should prioritize patching affected systems and implement proper access controls to limit local user privileges where possible. Additional protective measures include monitoring for suspicious write operations to kernel proc entries and implementing kernel hardening techniques such as stack canaries and address space layout randomization. The vulnerability also highlights the importance of proper input validation in kernel space code and demonstrates the critical need for rigorous code review processes in security-sensitive components of operating system kernels. Organizations should conduct thorough vulnerability assessments to identify systems running affected kernel versions and establish monitoring procedures to detect potential exploitation attempts against this and similar kernel-level vulnerabilities.