CVE-2007-2876 in Linux
Summary
by MITRE
The sctp_new function in (1) ip_conntrack_proto_sctp.c and (2) nf_conntrack_proto_sctp.c in Netfilter in Linux kernel 2.6 before 2.6.20.13, and 2.6.21.x before 2.6.21.4, allows remote attackers to cause a denial of service by causing certain invalid states that trigger a NULL pointer dereference.
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Analysis
by VulDB Data Team • 07/20/2019
The vulnerability identified as CVE-2007-2876 represents a critical denial of service flaw within the Linux kernel's Netfilter subsystem, specifically affecting the Stream Control Transmission Protocol implementation. This vulnerability exists in the sctp_new function located in two key files: ip_conntrack_proto_sctp.c and nf_conntrack_proto_sctp.c. The issue impacts Linux kernel versions prior to 2.6.20.13 and 2.6.21.4, creating a window of exposure across multiple kernel releases that were widely deployed in enterprise and infrastructure environments. The flaw manifests when certain invalid states are encountered during SCTP connection tracking, leading to a NULL pointer dereference that ultimately results in system instability and potential system crashes.
The technical mechanism underlying this vulnerability involves the improper handling of connection tracking states within the Netfilter framework. When the sctp_new function processes incoming SCTP packets, it fails to adequately validate the state transitions, particularly when encountering malformed or unexpected connection states. This validation gap allows remote attackers to craft specifically crafted SCTP packets that, when processed by the kernel's connection tracking module, trigger a NULL pointer dereference. The vulnerability is classified under CWE-476 as a NULL pointer dereference, which represents a fundamental flaw in memory management where the kernel attempts to access a null memory reference during connection state processing. The flaw is particularly dangerous because it can be exploited remotely without requiring any authentication or privileged access, making it a significant threat to network infrastructure systems.
The operational impact of this vulnerability extends beyond simple denial of service, as it can lead to complete system instability and potential system crashes that affect network connectivity and service availability. Network administrators and security teams face the challenge of identifying systems running vulnerable kernel versions and implementing timely patches. The vulnerability's exploitation can result in sustained service disruption, particularly in environments where SCTP is actively used for signaling protocols, multimedia streaming, or other critical network services. Organizations relying on Linux-based systems for network infrastructure, telecommunications equipment, or enterprise networking may experience cascading failures if multiple systems are simultaneously affected, as the denial of service can propagate across network segments and impact broader service availability.
Mitigation strategies for CVE-2007-2876 primarily focus on immediate kernel version updates to patched releases, specifically kernel versions 2.6.20.13 and 2.6.21.4 or later. System administrators should prioritize patch deployment across all affected systems, particularly those handling SCTP traffic or serving as network infrastructure components. Network segmentation and firewall rules can provide temporary mitigation by blocking SCTP traffic if it is not essential for operations, though this approach may impact legitimate services. The vulnerability also aligns with ATT&CK technique T1499.004 which covers network denial of service attacks, and organizations should consider implementing monitoring for unusual connection tracking patterns or system crashes that might indicate exploitation attempts. Additionally, maintaining up-to-date security patches and implementing robust kernel hardening measures provides defense in depth against similar vulnerabilities that may exist in older kernel versions or unpatched systems.