CVE-2017-9264 in vSwitch
Summary
by MITRE
In lib/conntrack.c in the firewall implementation in Open vSwitch (OvS) 2.6.1, there is a buffer over-read while parsing malformed TCP, UDP, and IPv6 packets in the functions `extract_l3_ipv6`, `extract_l4_tcp`, and `extract_l4_udp` that can be triggered remotely.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 12/07/2022
The vulnerability identified as CVE-2017-9264 represents a critical buffer over-read flaw within the Open vSwitch firewall implementation that affects version 2.6.1. This issue exists in the lib/conntrack.c file where the system processes network packets for connection tracking purposes. The flaw specifically manifests when the firewall encounters malformed TCP, UDP, or IPv6 packets that are processed through the extract_l3_ipv6, extract_l4_tcp, and extract_l4_udp functions. These functions are responsible for parsing packet headers and extracting relevant connection tracking information, but they fail to properly validate packet boundaries before accessing memory regions that could extend beyond the actual packet data.
The technical exploitation of this vulnerability occurs when remote attackers send specially crafted malformed packets to systems running Open vSwitch 2.6.1. The buffer over-read condition arises because the parsing functions do not adequately check the length of incoming packets against the expected header sizes before performing memory accesses. When processing IPv6 packets, the extract_l3_ipv6 function attempts to read beyond the allocated buffer space, while the extract_l4_tcp and extract_l4_udp functions exhibit similar behavior when handling TCP and UDP protocol headers respectively. This improper memory access can lead to unpredictable behavior including system crashes, denial of service conditions, or potentially more severe consequences if the over-read allows for information disclosure or code execution.
The operational impact of CVE-2017-9264 extends beyond simple service disruption as it affects the fundamental network security capabilities of Open vSwitch deployments. Organizations utilizing OvS for virtual networking and firewall services face significant risk when systems are exposed to untrusted network traffic, as attackers can remotely trigger the vulnerability without requiring authentication. The flaw particularly impacts virtualized environments where Open vSwitch serves as the primary network virtualization layer, potentially compromising entire virtual machine networks. Network administrators may experience unexpected system instability, connection tracking failures, and potential data exposure through memory leaks that occur during the over-read conditions.
Security mitigations for CVE-2017-9264 primarily involve upgrading to patched versions of Open vSwitch where the buffer over-read conditions have been addressed through proper input validation and boundary checking. Organizations should implement network segmentation and access controls to limit exposure to untrusted traffic while monitoring for potential exploitation attempts. The vulnerability aligns with CWE-125, which describes out-of-bounds read conditions, and represents a classic example of improper input validation in network protocol parsing. From an ATT&CK framework perspective, this vulnerability could be leveraged in initial access phases or as part of broader network reconnaissance activities, potentially enabling adversaries to establish persistent access or disrupt network operations. The remediation process should include comprehensive testing of patched versions in staging environments before production deployment to ensure no regression in network functionality while addressing the specific buffer over-read conditions that were present in the vulnerable implementation.