CVE-2016-2071 in Netscaler Application Delivery Controller
Summary
by MITRE
Citrix NetScaler Application Delivery Controller (ADC) and NetScaler Gateway 11.x before 11.0 Build 64.34, 10.5 before 10.5 Build 59.13, and 10.5.e before Build 59.1305.e allows remote attackers to gain privileges via unspecified NS Web GUI commands.
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Analysis
by VulDB Data Team • 07/08/2022
The Citrix NetScaler ADC and NetScaler Gateway appliances represent critical components in enterprise network infrastructure, serving as application delivery controllers and secure access gateways that manage traffic flow and user authentication. These appliances are widely deployed across organizations to provide load balancing, application acceleration, and secure remote access capabilities. The vulnerability identified as CVE-2016-2071 specifically targets the NS Web GUI interface, which serves as the primary administrative portal for configuring and managing these critical network components. This vulnerability exists within multiple version ranges including 11.x before 11.0 Build 64.34, 10.5 before 10.5 Build 59.13, and 10.5.e before Build 59.1305.e, indicating a widespread exposure across several major release lines. The flaw allows remote attackers to execute unspecified NS Web GUI commands with elevated privileges, effectively bypassing normal authentication and authorization mechanisms that should protect administrative functions.
The technical nature of this vulnerability stems from inadequate input validation and privilege escalation mechanisms within the Web GUI administrative interface. Attackers can exploit this weakness to execute arbitrary commands through the web-based management interface without proper authentication, potentially gaining root-level access to the appliance. This type of vulnerability typically falls under CWE-264, which encompasses permissions, privileges, and access control issues, specifically targeting the improper handling of administrative privileges within network infrastructure devices. The vulnerability's remote exploitability means that attackers do not require physical access or local network presence to target affected systems, making it particularly dangerous in environments where these appliances are exposed to external networks.
The operational impact of CVE-2016-2071 is severe and multifaceted, potentially allowing attackers to completely compromise the affected NetScaler appliances and the networks they protect. Once exploited, attackers could gain full administrative control over the appliance, enabling them to modify network configurations, redirect traffic, implement man-in-the-middle attacks, or establish persistent backdoors within the network infrastructure. This vulnerability directly impacts the CIA triad by compromising confidentiality through unauthorized access to sensitive network configuration data, integrity by allowing modification of critical network policies, and availability by potentially disrupting network services. The attack surface extends beyond individual appliance compromise to potentially affect entire enterprise networks that rely on these appliances for secure access and application delivery, as demonstrated by various attack patterns documented in the MITRE ATT&CK framework under techniques related to privilege escalation and lateral movement within network environments.
Organizations affected by this vulnerability should immediately implement mitigations including applying the vendor-provided security patches and updates, restricting access to the NS Web GUI through network segmentation, implementing strict firewall rules to limit access to administrative interfaces, and monitoring network traffic for suspicious activities. The vulnerability's classification as a remote privilege escalation issue aligns with ATT&CK technique T1068, which covers local privilege escalation, but in this case the escalation occurs remotely through the web interface. Additional security measures should include regular vulnerability assessments, network monitoring for unauthorized administrative access attempts, and implementing multi-factor authentication for administrative access where possible. The incident response plan should include immediate isolation of affected appliances, thorough forensic analysis of compromised systems, and coordination with Citrix security teams for comprehensive remediation guidance.