CVE-2018-15320 in BIG-IP
Summary
by MITRE
On BIG-IP 14.0.0-14.0.0.2 or 13.0.0-13.1.1.1, undisclosed traffic patterns may lead to denial of service conditions for the BIG-IP system. The configuration which exposes this condition is the BIG-IP self IP address which is part of a VLAN group and has the Port Lockdown setting configured with anything other than "allow-all".
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Analysis
by VulDB Data Team • 06/04/2023
The vulnerability described in CVE-2018-15320 represents a significant denial of service weakness within F5 BIG-IP systems that affects specific version ranges including 14.0.0 through 14.0.0.2 and 13.0.0 through 13.1.1.1. This issue manifests through undisclosed traffic patterns that can compromise system availability when certain network configuration parameters are in place. The vulnerability operates at the network layer where traffic flow is controlled through self IP address configurations within VLAN groups, making it particularly concerning for enterprise network infrastructure that relies on F5 load balancers and application delivery controllers.
The technical flaw stems from the interaction between the Port Lockdown setting and self IP address configurations within VLAN groups. When a BIG-IP system's self IP address is configured within a VLAN group with Port Lockdown set to any value other than "allow-all", the system becomes susceptible to traffic pattern manipulation that can trigger denial of service conditions. This configuration creates a scenario where specific traffic flows can cause the system to become unresponsive or fail to process legitimate requests, effectively disrupting network services for applications and users relying on the BIG-IP infrastructure. The vulnerability is classified under CWE-284 as an improper access control issue, where the system fails to properly restrict access to network resources based on configuration parameters.
The operational impact of this vulnerability extends beyond simple service disruption to potentially affect critical business applications and services that depend on F5 BIG-IP systems for load balancing, traffic management, and application delivery. Organizations running affected versions may experience complete service outages during attack scenarios, leading to significant business disruption and potential financial losses. The vulnerability is particularly dangerous because it can be triggered through traffic manipulation rather than requiring direct system compromise, making it more difficult to detect and prevent. This weakness aligns with ATT&CK technique T1499.004 for network denial of service attacks, where adversaries can exploit system configurations to cause service unavailability.
Mitigation strategies for CVE-2018-15320 should focus on immediate configuration changes to address the root cause of the vulnerability. Organizations should review and modify their Port Lockdown settings for self IP addresses within VLAN groups, ensuring that configurations align with security best practices while maintaining necessary service availability. The recommended approach involves either setting Port Lockdown to "allow-all" or carefully configuring specific port restrictions that do not inadvertently create denial of service conditions. Network administrators should also implement monitoring solutions to detect unusual traffic patterns that might indicate exploitation attempts, as the vulnerability can be triggered through legitimate network traffic manipulation. Additionally, upgrading to patched versions of F5 BIG-IP software represents the most effective long-term solution, as these updates typically include fixes for the underlying configuration handling and traffic pattern processing logic. The vulnerability demonstrates the importance of proper network segmentation and access control configuration in enterprise security architectures, where misconfigured network elements can create exploitable conditions that affect system availability and service delivery.