CVE-2018-5514 in BIG-IP
Summary
by MITRE
On F5 BIG-IP 13.1.0-13.1.0.5, maliciously crafted HTTP/2 request frames can lead to denial of service. There is data plane exposure for virtual servers when the HTTP2 profile is enabled. There is no control plane exposure to this issue.
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Analysis
by VulDB Data Team • 03/08/2023
The vulnerability identified as CVE-2018-5514 represents a critical denial of service weakness affecting F5 BIG-IP systems running version 13.1.0 through 13.1.0.5. This flaw specifically targets the HTTP/2 protocol implementation within the BIG-IP traffic management platform, creating a data plane exposure that allows remote attackers to disrupt service availability. The vulnerability manifests when the HTTP2 profile is enabled on virtual servers, making it particularly concerning for organizations that rely on HTTP/2 for performance optimization and modern web application delivery. Unlike control plane vulnerabilities that might affect management interfaces or configuration capabilities, this issue operates entirely within the data plane, meaning it impacts the actual traffic processing capabilities of the device rather than administrative functions.
The technical mechanism behind this vulnerability involves the improper handling of maliciously crafted HTTP/2 request frames that can cause the BIG-IP system to crash or become unresponsive. When an HTTP/2 profile is active on a virtual server, the system processes incoming HTTP/2 requests through a specific parsing and handling mechanism that fails to properly validate or sanitize malformed frames. This processing failure results in resource exhaustion or internal state corruption that leads to complete service disruption. The flaw is classified as a CWE-400 vulnerability, specifically related to unspecified denial of service conditions in network protocols, and aligns with ATT&CK technique T1499.004 for network denial of service attacks. Attackers can exploit this weakness by sending carefully constructed HTTP/2 frames that trigger the system's processing logic to enter an unrecoverable state, effectively rendering the affected virtual servers unavailable to legitimate users.
The operational impact of CVE-2018-5514 extends beyond simple service interruption, as it can affect critical business applications and services that depend on F5 BIG-IP for load balancing, SSL termination, and application delivery. Organizations utilizing HTTP/2 profiles for performance optimization face significant risk, as the vulnerability can be exploited remotely without authentication, making it particularly dangerous in publicly accessible environments. The lack of control plane exposure means that attackers cannot compromise management interfaces or configuration settings through this specific vulnerability, but the data plane impact can be devastating for service availability. This vulnerability affects the fundamental traffic processing capabilities of the BIG-IP system, potentially causing cascading failures across multiple virtual servers and applications that rely on the affected platform for their delivery infrastructure.
Mitigation strategies for CVE-2018-5514 primarily involve applying the official F5 security patches released in response to this vulnerability, which address the HTTP/2 frame parsing logic to properly handle malformed requests. Organizations should also consider implementing temporary workarounds such as disabling HTTP/2 profiles on virtual servers until patches can be deployed, or implementing network-level controls to filter suspicious HTTP/2 traffic patterns. Additionally, monitoring systems should be enhanced to detect unusual traffic patterns or potential exploitation attempts targeting this specific vulnerability. The remediation process should follow F5's recommended procedures for patch management and system updates, ensuring that all affected BIG-IP devices receive the appropriate security updates. Organizations may also want to review their HTTP/2 implementation strategies and consider alternative protocols or additional security controls to reduce the attack surface for similar vulnerabilities in the future.