External risk intelligence

Citrix NetScaler Gateway Information Disclosure.

CVE advisoryKnown Exploit

CVE-2023-4966

The NetScaler ADC and NetScaler Gateway are affected by a vulnerability enabling sensitive information disclosure. This matters because unauthorized access to confidential data can occur when these systems are configured as Gateways. The business risk involves potential exposure of organizational data.

5Halo Surface Signal

Memory Corruption

Citrix Netscaler Application Delivery Controller

12.1 to before 12.1-55.30013.0 to before 13.0-92.1913.1 to before 13.1-37.16413.1 to before 13.1-49.1514.1 to before 14.1-8.50

External exposure likelihood

Halo Surface Signal score for CVE-2023-4966

This vulnerability affects NetScaler ADC and NetScaler Gateway when configured as a VPN, ICA Proxy, CVPN, RDP Proxy, or AAA virtual server. These components are specifically designed to serve as internet-facing gateways and remote access portals, making them public-facing by design in standard deployments.

Horizon Alert

Summary of the vulnerability and why it matters

Citrix NetScaler ADC and NetScaler Gateway products are affected by a vulnerability that can lead to the disclosure of sensitive information. This flaw exists when these products are configured to act as a Gateway, such as for VPN or remote access services. The improper handling of data can allow unauthorized access to confidential details.

NetScaler ADC and Gateway components
Flaw allows sensitive information disclosure
Risk of data exposure for organizations

Attack Path

How an attacker could exploit the issue

This vulnerability impacts organizations using NetScaler ADC and NetScaler Gateway in specific configurations. An attacker can exploit this by sending a specially crafted request to an affected virtual server. Successful exploitation allows the attacker to disclose sensitive information from the system.

External network exposure
Unauthenticated attacker access
Triggered by a crafted request, results in data disclosure

Live Threat

Current exploitation, exposure, and threat context

This vulnerability allows for the disclosure of sensitive information from NetScaler ADC and NetScaler Gateway when these systems are configured for gateway services. Attackers could potentially gain access to confidential data without needing special privileges or complex methods. The potential for unauthorized data exposure presents a significant risk to affected organizations.

Likely attacker skill level: Low
Required access or conditions: None
Business risk or urgency: High

Priority actions

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability allows for the disclosure of sensitive information when NetScaler ADC and NetScaler Gateway are configured as a Gateway or AAA virtual server. Organizations utilizing these configurations should prioritize actions to mitigate risk and protect data. The highest risk is to data confidentiality due to the nature of the vulnerability.

Identify all NetScaler ADC and NetScaler Gateway assets.
Isolate affected systems or reduce exposure.
Apply vendor fixes, verify, and monitor.

Frequently asked questions

What are NetScaler ADC and NetScaler Gateway and what do they do?

NetScaler ADC and NetScaler Gateway are products from Citrix that act as application delivery controllers and network gateways. They are used to manage, secure, and optimize access to applications and services, often for remote users or for load balancing within an organization's network. They can be configured for various gateway functions like VPN, ICA proxy, and AAA services.

How does CVE-2023-4966 lead to sensitive information disclosure?

CVE-2023-4966 is a weakness classified as CWE-119, which typically relates to buffer handling errors. In NetScaler ADC and Gateway, this flaw allows an attacker to disclose sensitive information from the system when it's configured as a gateway. This means confidential data could be exposed to unauthorized parties.

What are the conditions for an attacker to exploit this vulnerability?

An attacker can exploit this vulnerability by sending a specially crafted request to an affected virtual server. The advisory indicates that no special privileges or complex methods are required, suggesting that an unauthenticated attacker could potentially trigger this flaw. It is not triggered if the system is not configured as a Gateway or AAA virtual server.

Who should be concerned about this threat based on its exposure?

Organizations using NetScaler ADC and NetScaler Gateway, particularly when configured as internet-facing gateways or remote access portals, should be concerned. The Halo Surface Signal indicates this vulnerability is 'Very likely' to be exploited externally because these configurations are inherently designed to be accessible from the internet.

What is the first step for managing this vulnerability?

The initial step for organizations running this technology is to identify all instances of NetScaler ADC and NetScaler Gateway within their environment. Following identification, it's recommended to isolate affected systems or reduce their exposure where possible while preparing to apply vendor-provided fixes.

References

Written by Nicholas Merritt

External-surface CVE analysis and Halo Surface Signal prioritization for Halo Threat Intelligence.