CVE-2018-6809 in NetScaler ADC
Summary
by MITRE
NetScaler ADC 10.5, 11.0, 11.1, and 12.0, and NetScaler Gateway 10.5, 11.0, 11.1, and 12.0 allow remote attackers to gain privilege on a target system.
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Analysis
by VulDB Data Team • 02/17/2023
The vulnerability identified as CVE-2018-6809 represents a critical privilege escalation flaw affecting Citrix NetScaler ADC and NetScaler Gateway appliances across multiple versions including 10.5, 11.0, 11.1, and 12.0. This vulnerability resides within the authentication and authorization mechanisms of these network security appliances, which are widely deployed in enterprise environments for load balancing, application delivery, and secure remote access solutions. The affected systems operate as critical infrastructure components that handle sensitive traffic and user authentication, making them attractive targets for malicious actors seeking to elevate their privileges within network environments. The vulnerability allows remote attackers to execute arbitrary code with elevated privileges, potentially compromising the entire appliance and underlying network infrastructure.
The technical flaw stems from improper input validation and insufficient access control checks within the NetScaler management interfaces. Specifically, the vulnerability occurs when the system processes certain administrative commands or API calls without adequate authorization verification, enabling attackers to bypass normal authentication procedures. This weakness manifests in the way the appliance handles privilege levels during administrative operations, where insufficient validation allows unauthenticated or low-privileged users to escalate their access rights. The flaw can be exploited through network-based attacks that do not require physical access or prior authentication credentials, making it particularly dangerous for systems deployed in publicly accessible environments. The vulnerability is classified under CWE-284, which addresses improper access control issues, and aligns with ATT&CK technique T1068, which covers privilege escalation through exploitation of system vulnerabilities.
The operational impact of CVE-2018-6809 extends far beyond the immediate compromise of individual appliances, as these devices often serve as central points of control for enterprise network traffic and user authentication. Successful exploitation could enable attackers to gain full administrative control over the affected systems, allowing them to modify configurations, intercept and manipulate network traffic, establish persistent backdoors, and potentially move laterally throughout the network. Organizations relying on NetScaler appliances for critical infrastructure protection face significant risks including data breaches, service disruption, and compliance violations. The vulnerability affects both NetScaler ADC and NetScaler Gateway components, meaning that enterprises utilizing either or both systems could be compromised, with potential impacts ranging from denial of service to complete system takeover and data exfiltration.
Mitigation strategies for CVE-2018-6809 require immediate action from affected organizations to patch their NetScaler appliances using official Citrix security updates. Organizations should implement network segmentation to limit access to administrative interfaces, enforce strict firewall rules, and monitor for unusual administrative activities. Additional protective measures include disabling unnecessary services, implementing multi-factor authentication for administrative access, and conducting regular security assessments of network infrastructure. The vulnerability demonstrates the importance of maintaining up-to-date security patches and following secure configuration practices as outlined in industry standards such as NIST SP 800-125 and ISO/IEC 27001. Organizations should also consider implementing intrusion detection systems to monitor for exploitation attempts and establish incident response procedures specifically addressing privilege escalation vulnerabilities in critical infrastructure components.