CVE-2013-2128 in Linux
Summary
by MITRE
The tcp_read_sock function in net/ipv4/tcp.c in the Linux kernel before 2.6.34 does not properly manage skb consumption, which allows local users to cause a denial of service (system crash) via a crafted splice system call for a TCP socket.
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Analysis
by VulDB Data Team • 01/03/2022
The vulnerability identified as CVE-2013-2128 represents a critical flaw in the Linux kernel's TCP implementation that specifically affects versions prior to 2.6.34. This issue resides within the tcp_read_sock function located in the net/ipv4/tcp.c source file, where improper management of socket buffer (skb) consumption creates a condition that can be exploited by local attackers to trigger system crashes. The vulnerability is particularly concerning because it operates at the kernel level, meaning that successful exploitation can result in complete system instability and denial of service conditions that may require manual rebooting to resolve.
The technical root cause of this vulnerability stems from how the kernel handles socket buffer management during splice operations on TCP sockets. When a crafted splice system call is executed against a TCP socket, the tcp_read_sock function fails to properly account for or consume the socket buffers that are being processed. This improper buffer management leads to a situation where the kernel's memory management subsystem becomes corrupted, ultimately causing the system to crash with a kernel oops or similar fatal error condition. The flaw is classified as a buffer over-read or improper resource handling issue, which aligns with CWE-125: Uncontrolled Buffer Access and CWE-129: Improper Validation of Array Index.
From an operational perspective, this vulnerability presents a significant risk to systems running affected kernel versions, particularly those that might be exposed to untrusted local users or applications that could potentially execute splice operations. The local nature of the attack means that an attacker must already have access to the system, but this access could be gained through various vectors such as compromised user accounts, malicious applications, or privilege escalation exploits. The impact extends beyond simple system crashes, as these crashes can occur repeatedly and may be difficult to recover from without manual intervention, potentially leading to extended downtime and service disruption for critical infrastructure.
The exploitation of this vulnerability can be categorized under the ATT&CK framework's privilege escalation and defense evasion techniques, specifically mapping to T1068: Exploitation for Privilege Escalation and T1499.1: Endpoint Denial of Service. Organizations should implement immediate mitigation strategies including kernel updates to versions 2.6.34 or later where this vulnerability has been patched. Additionally, system administrators should consider implementing monitoring solutions that can detect anomalous splice system call patterns and potential exploitation attempts. The patch for this vulnerability involved proper handling of socket buffer consumption within the tcp_read_sock function, ensuring that all processed socket buffers are correctly accounted for and released. Regular kernel updates and security audits remain essential practices for maintaining system integrity and preventing exploitation of similar kernel-level vulnerabilities that may exist in older or unpatched systems.