CVE-2019-5274 in USG9500
Summary
by MITRE
USG9500 with versions of V500R001C30;V500R001C60 have a denial of service vulnerability. Due to a flaw in the X.509 implementation in the affected products which can result in an infinite loop, an attacker may exploit the vulnerability via a malicious certificate to perform a denial of service attack on the affected products.
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Analysis
by VulDB Data Team • 03/17/2024
The vulnerability identified as CVE-2019-5274 affects the USG9500 firewall series running specific firmware versions V500R001C30 and V500R001C60. This represents a critical denial of service weakness that fundamentally compromises the availability of network security services. The affected devices operate within enterprise and government network infrastructures where uninterrupted firewall operations are essential for maintaining security perimeters and protecting against external threats.
The technical flaw resides within the X.509 certificate processing implementation of the affected USG9500 devices. This vulnerability manifests as an infinite loop condition that occurs when the system attempts to parse maliciously crafted X.509 certificates. The flaw specifically impacts the certificate validation mechanism that handles digital certificates used for secure communications and identity verification. When an attacker submits a specially crafted certificate designed to trigger this processing loop, the device's CPU utilization spikes to 100% and the system becomes unresponsive, effectively rendering the firewall incapable of performing its core security functions.
The operational impact of this vulnerability extends beyond simple service disruption as it creates a significant security risk for organizations relying on these firewalls. Network administrators face the challenge of maintaining continuous security operations while the affected devices become unavailable. The infinite loop condition prevents the system from processing legitimate network traffic, creating a denial of service scenario that can persist until the device is manually rebooted or the certificate processing is interrupted. This vulnerability particularly affects environments where the firewall must process certificates from external sources or where certificate-based authentication is utilized, such as SSL termination points, VPN gateways, or secure email servers.
Mitigation strategies for CVE-2019-5274 require immediate attention from network security teams and should include firmware updates from the vendor to address the specific implementation flaw in X.509 processing. Organizations should implement certificate filtering mechanisms to prevent malicious certificates from reaching the affected systems, utilizing certificate trust stores and validation policies to reject suspicious or malformed certificates. Network segmentation and redundant security controls can help minimize the impact if the vulnerability is exploited, while monitoring systems should be configured to detect unusual CPU utilization patterns that may indicate exploitation attempts. This vulnerability aligns with CWE-835, which addresses infinite loops in software implementations, and could be categorized under ATT&CK technique T1499.004 for network denial of service attacks, highlighting the need for comprehensive network resilience and monitoring capabilities.
The broader implications of this vulnerability demonstrate the critical importance of certificate validation security in enterprise network infrastructure, where flaws in cryptographic implementation can result in complete system compromise. Organizations should conduct thorough vulnerability assessments of their entire network security infrastructure to identify similar implementation weaknesses and ensure robust certificate management practices are in place to prevent exploitation of similar vulnerabilities in the future.