CVE-2016-9028 in NetScaler
Summary
by MITRE
Unauthorized redirect vulnerability in Citrix NetScaler ADC before 10.1 135.8, 10.5 61.11, 11.0 65.31/65.35F and 11.1 47.14 allows a remote attacker to steal session cookies of a legitimate AAA user via manipulation of Host header.
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Analysis
by VulDB Data Team • 09/17/2024
The CVE-2016-9028 vulnerability represents a critical unauthorized redirect flaw in Citrix NetScaler Application Delivery Controller appliances that affects multiple version ranges including 10.1 through 10.5, 11.0, and 11.1 releases. This vulnerability specifically targets the authentication and authorization mechanisms within the NetScaler ADC platform, creating a significant security risk for organizations relying on these appliances for application delivery and security services. The flaw stems from improper validation of the Host header parameter during authentication flows, allowing malicious actors to manipulate session handling and potentially compromise user sessions.
The technical exploitation of this vulnerability occurs through manipulation of the HTTP Host header field, which is typically used by web servers to determine which virtual host should receive a request. In the affected Citrix NetScaler versions, the appliance fails to properly validate or sanitize the Host header value during the authentication process, enabling attackers to craft malicious requests that redirect legitimate AAA users to attacker-controlled domains. This creates an opportunity for session hijacking attacks where the attacker can intercept and steal session cookies, effectively impersonating authenticated users within the network environment. The vulnerability specifically impacts the AAA (Authentication, Authorization, and Accounting) functionality of the NetScaler appliance, which is fundamental to user access control and network security.
From an operational impact perspective, this vulnerability exposes organizations to serious security threats including unauthorized access to protected resources, data breaches, and potential lateral movement within the network. Attackers can leverage this flaw to steal session tokens and gain access to sensitive applications and services protected by the NetScaler appliance. The vulnerability's remote nature means that attackers do not require physical access or network proximity to exploit the flaw, making it particularly dangerous in environments where the appliance serves as a critical gateway for enterprise applications. Organizations may experience unauthorized access to corporate resources, compromise of user credentials, and potential escalation of privileges through the stolen session information, all while maintaining the appearance of legitimate user activity within the network monitoring systems.
The vulnerability aligns with CWE-601, which addresses URL redirect vulnerabilities, and can be mapped to ATT&CK technique T1566 for social engineering attacks and T1071 for application layer protocols. Effective mitigation strategies include immediate deployment of Citrix's official patches and security updates for the affected versions, implementation of proper Host header validation mechanisms, and network segmentation to limit the attack surface. Organizations should also consider implementing additional monitoring for unusual redirect patterns and Host header manipulations, along with regular security assessments of their NetScaler configurations. The recommended remediation approach involves upgrading to patched versions of Citrix NetScaler ADC, configuring proper input validation for Host headers, and establishing robust session management policies that include secure cookie attributes such as HttpOnly and Secure flags. Network administrators should also implement proper logging and monitoring to detect anomalous authentication behavior and redirect attempts that could indicate exploitation of this vulnerability.