CVE-2020-8246 in ADC
Summary
by MITRE
Citrix ADC and Citrix Gateway 13.0 before 13.0-64.35, Citrix ADC and NetScaler Gateway 12.1 before 12.1-58.15, Citrix ADC 12.1-FIPS before 12.1-55.187, Citrix ADC and NetScaler Gateway 12.0, Citrix ADC and NetScaler Gateway 11.1 before 11.1-65.12, Citrix SD-WAN WANOP 11.2 before 11.2.1a, Citrix SD-WAN WANOP 11.1 before 11.1.2a, Citrix SD-WAN WANOP 11.0 before 11.0.3f, Citrix SD-WAN WANOP 10.2 before 10.2.7b are vulnerable to a denial of service attack originating from the management network.
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Analysis
by VulDB Data Team • 09/19/2020
Citrix ADC and Citrix Gateway appliances represent critical infrastructure components in enterprise networking and application delivery, serving as traffic managers, load balancers, and secure access gateways for organizations worldwide. These appliances are designed to handle high volumes of network traffic while maintaining security through various authentication and authorization mechanisms. The vulnerability described in CVE-2020-8246 specifically targets the management network interface of these systems, creating a significant risk for organizations that rely on these appliances for their network infrastructure. The affected versions span multiple Citrix product lines including ADC, NetScaler Gateway, and SD-WAN WANOP appliances, indicating a widespread impact across the Citrix product portfolio. This vulnerability allows attackers to initiate denial of service conditions that can disrupt critical network services and potentially compromise the availability of enterprise applications and resources.
The technical flaw in CVE-2020-8246 stems from inadequate input validation and resource management within the management interface processing logic of Citrix appliances. When maliciously crafted packets are sent to the management network interface, they can trigger an unexpected behavior in the appliance's processing stack that leads to resource exhaustion or system instability. This vulnerability specifically affects the handling of certain management protocol messages or configuration requests that are processed by the appliance's management services. The flaw likely resides in the parsing or validation of management interface communications, where insufficient bounds checking or error handling allows malformed data to cause the system to enter a non-responsive state. This type of vulnerability falls under the CWE-129 weakness category, which deals with insufficient validation of the length or size of input data, and can be classified as a CWE-400 weakness related to resource exhaustion. The attack vector requires network access to the management interface, making it particularly dangerous for appliances that have exposed management networks or insufficient network segmentation.
The operational impact of this vulnerability extends beyond simple service disruption, as Citrix ADC and Gateway appliances often serve as foundational components in enterprise network architectures. When these appliances become unavailable due to the denial of service attack, it can result in cascading failures throughout the organization's network infrastructure, affecting application availability, user access, and business continuity. The management interface being compromised means that administrators may lose the ability to monitor, configure, or troubleshoot the appliance remotely, which can significantly extend recovery times and increase the impact of the attack. Organizations that have not properly segmented their management networks or have exposed these interfaces to untrusted networks face the highest risk of exploitation. The vulnerability can be exploited by attackers who gain access to the management network, which could occur through various means including network reconnaissance, credential compromise, or exploitation of other vulnerabilities in the network perimeter. This attack pattern aligns with the ATT&CK technique T1499.004 for network denial of service, where adversaries target network infrastructure to disrupt services.
Mitigation strategies for CVE-2020-8246 should focus on both immediate protective measures and long-term security improvements. Organizations should prioritize applying the vendor-provided security patches and updates that address this specific vulnerability, as these fixes typically contain proper input validation and resource management controls. Network segmentation represents a crucial defensive measure, ensuring that management interfaces are not directly accessible from untrusted networks and that appropriate firewall rules are implemented to restrict access to these interfaces. Access controls should be strictly enforced, limiting management interface access to authorized personnel only and implementing multi-factor authentication where possible. Monitoring and logging capabilities should be enhanced to detect unusual activity on management interfaces, as this vulnerability may be preceded by reconnaissance attempts or other malicious activities. Network administrators should also implement intrusion detection systems that can identify and alert on suspicious traffic patterns targeting management interfaces. The remediation process should include comprehensive testing of patched systems to ensure that the vulnerability has been properly addressed without introducing new issues. Organizations should also consider implementing network access control policies that limit the scope of management interface access and regularly audit these configurations to maintain security posture. Compliance with industry standards such as NIST SP 800-53 and ISO 27001 should be maintained to ensure that appropriate security controls are in place to protect against this and similar vulnerabilities.