CVE-2015-5538 in Netscaler Application Delivery Controller
Summary
by MITRE
Multiple unspecified vulnerabilities in Citrix NetScaler Application Delivery Controller (ADC) and NetScaler Gateway before 10.1 Build 132.8, 10.5 before Build 57.7, and 10.5e before Build 56.1505.e allow remote attackers to gain privileges via unknown vectors, related to the (1) Command Line Interface (CLI) and the (2) Web User Interface (UI).
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Analysis
by VulDB Data Team • 06/15/2022
The vulnerability identified as CVE-2015-5538 represents a critical privilege escalation issue affecting Citrix NetScaler Application Delivery Controller and NetScaler Gateway appliances across multiple software versions. This vulnerability stems from unspecified flaws within the command line interface and web user interface components of these network security appliances, creating potential pathways for remote attackers to elevate their privileges and gain unauthorized administrative access to the affected systems. The affected versions include Citrix NetScaler ADC and Gateway releases prior to specific build numbers, indicating a widespread impact across the product lineage.
The technical nature of this vulnerability lies in the improper handling of authentication and authorization mechanisms within the CLI and UI components of the Citrix appliances. Attackers can exploit these unspecified vectors to bypass normal access controls and escalate their privileges from standard user levels to administrative privileges without requiring valid credentials for the highest privilege accounts. This type of vulnerability directly maps to CWE-276, which addresses improper privileges, and represents a significant weakness in the principle of least privilege enforcement within the affected systems. The vulnerability's remote exploitability means that attackers do not need physical access or local network presence to carry out the attack, making it particularly dangerous in networked environments.
The operational impact of CVE-2015-5538 is severe and far-reaching, as successful exploitation would allow attackers to gain complete administrative control over the affected Citrix appliances. This level of access would enable threat actors to modify network configurations, implement man-in-the-middle attacks, redirect traffic, and potentially compromise the entire network infrastructure managed by these appliances. The vulnerability could be leveraged to establish persistent backdoors, exfiltrate sensitive data, or disrupt critical network services, making it a prime target for advanced persistent threats. Organizations relying on Citrix NetScaler appliances for application delivery and gateway services would face significant security risks, potentially affecting thousands of connected applications and services.
Mitigation strategies for this vulnerability should focus on immediate patching of affected systems to the latest available builds that address the privilege escalation flaws. Organizations must also implement network segmentation to limit access to these critical appliances and establish strict access controls for administrative interfaces. The implementation of network monitoring solutions can help detect unusual administrative activities that might indicate exploitation attempts. Additionally, regular security assessments and vulnerability scanning should be conducted to identify any remaining weaknesses in the network infrastructure. According to ATT&CK framework, this vulnerability would be categorized under privilege escalation techniques, specifically targeting the T1068 - Exploitation for Privilege Escalation tactic, making comprehensive defensive measures essential for protecting against such attacks. Organizations should also consider implementing multi-factor authentication for administrative access and establish robust logging and alerting mechanisms to detect unauthorized privilege escalation attempts.