Hackers Exploiting Critical Zero-Day Vulnerability in Citrix NetScaler Products

NetScaler ADC and NetScaler Gateway (previously Citrix ADC and Citrix Gateway) contain multiple discovered vulnerabilities.

Citrix ADC is a powerful networking solution that ensures fast, secure, and reliable delivery of applications across networks.

While the NetScaler Gateway is a secure remote access solution that enables users to access their applications and data from anywhere securely.

Citrix recently issued a security bulletin, cautioning users about three new vulnerabilities impacting their above-mentioned product line.

Here below, we have mentioned those three vulnerabilities:-

• CVE-2023-3466
• CVE-2023-3467
• CVE-2023-3519

Hackers Exploiting Zero-Day

While the cybersecurity analysts at Rapid7 marked the CVE-2023-3519 as the critical zero-day vulnerability among the three, enabling unauthenticated attackers to execute code on vulnerable Gateway systems remotely.

Since the CVE-2023-3519 is currently exploited in the wild, poses a significant risk. Due to the popularity of this product line among threat actors, Rapid7 advises immediate emergency updates instead of waiting for the regular patch cycle.

To exploit the security issue, hackers target vulnerable appliances configured as gateways (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) or authentication virtual servers (AAA server).

Zero-Day flaw profile

• CVE ID: CVE-2023-3519
• Description: Unauthenticated remote code execution
• CVSS: 9.8
• Severity: Critical
• CWE: CWE-94
• Pre-requisites: Appliance must be configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) OR AAA virtual server.

Affected Products

The vulnerabilities impact the following supported versions of NetScaler ADC and NetScaler Gateway:-

• NetScaler ADC and NetScaler Gateway 13.1 before 13.1-49.13
• NetScaler ADC and NetScaler Gateway 13.0 before 13.0-91.13
• NetScaler ADC 13.1-FIPS before 13.1-37.159
• NetScaler ADC 12.1-FIPS before 12.1-65.36
• NetScaler ADC 12.1-NDcPP before 12.65.36

Fixed Product Versions

Here below we have mentioned all the fixed product versions:-

• NetScaler ADC and NetScaler Gateway 13.1-49.13  and later releases
• NetScaler ADC and NetScaler Gateway 13.0-91.13  and later releases of 13.0
• NetScaler ADC 13.1-FIPS 13.1-37.159 and later releases of 13.1-FIPS
• NetScaler ADC 12.1-FIPS 12.1-65.36 and later releases of 12.1-FIPS
• NetScaler ADC 12.1-NDcPP 12.1-65.36 and later releases of 12.1-NDcPP

Moreover, to mitigate these security flaws, make sure to apply patches in affected versions of NetScaler ADC and NetScaler Gateway on an immediate basis.