CVE-2017-2634 in Linux
Summary
by MITRE
It was found that the Linux kernel's Datagram Congestion Control Protocol (DCCP) implementation before 2.6.22.17 used the IPv4-only inet_sk_rebuild_header() function for both IPv4 and IPv6 DCCP connections, which could result in memory corruptions. A remote attacker could use this flaw to crash the system.
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Analysis
by VulDB Data Team • 04/27/2023
The vulnerability identified as CVE-2017-2634 represents a critical memory corruption flaw within the Linux kernel's implementation of the Datagram Congestion Control Protocol. This issue specifically affects kernel versions prior to 2.6.22.17 and demonstrates a fundamental design flaw in how the networking stack handles protocol-specific header rebuilding operations. The root cause lies in the improper function selection where the IPv4-only inet_sk_rebuild_header() routine was being invoked for both IPv4 and IPv6 DCCP connections, creating a mismatch between the expected and actual network protocol handling mechanisms.
This technical flaw manifests through the incorrect application of IPv4-specific header rebuilding logic to IPv6 connections, resulting in memory corruption vulnerabilities that can be exploited by remote attackers. The improper function usage creates a scenario where memory structures intended for IPv4 protocol handling are manipulated in ways that are incompatible with IPv6 addressing schemes, leading to unpredictable memory behavior and potential system crashes. The vulnerability operates at the kernel level within the networking subsystem, making it particularly dangerous as it can be triggered through network-based attacks without requiring local system access or authentication.
The operational impact of this vulnerability extends beyond simple system crashes, as it represents a potential vector for denial-of-service attacks that could be exploited at scale across networked environments. Remote attackers capable of sending specially crafted DCCP packets to vulnerable systems could trigger the memory corruption conditions, potentially leading to system instability, service disruption, and in some cases, privilege escalation opportunities. The nature of the flaw means that any system running affected kernel versions and actively processing DCCP traffic would be at risk, making this vulnerability particularly concerning for network infrastructure components and servers that handle diverse network protocols.
Mitigation strategies for CVE-2017-2634 require immediate kernel version updates to 2.6.22.17 or later, which contain the necessary patches that properly distinguish between IPv4 and IPv6 DCCP connection handling. System administrators should prioritize patching all affected systems, particularly those serving as network infrastructure components or handling DCCP traffic. Additionally, network segmentation and firewall rules can be implemented to restrict DCCP traffic where possible, though this approach provides only partial protection since the vulnerability exists within the kernel's core networking functionality. The fix addresses the underlying CWE-121 heap-based buffer overflow condition by ensuring proper protocol-specific header rebuilding functions are called for each respective network protocol, thereby preventing the memory corruption scenarios that could lead to system instability or compromise.
This vulnerability aligns with ATT&CK technique T1059.007 for remote code execution through kernel exploits and represents a classic example of improper input validation in kernel space networking code. The flaw demonstrates how protocol implementation mismatches can create security vulnerabilities that bypass traditional network security controls, highlighting the importance of thorough protocol testing and validation in kernel development processes. Organizations should implement comprehensive patch management procedures and monitor for similar issues in other kernel networking components that may exhibit similar protocol handling inconsistencies.