CVE-2023-4966

Published Oct 10, 2023

Last updated 3 months ago

CitrixBleed

Overview

AI description

Automated description summarized from trusted sources.

CVE-2023-4966 is a vulnerability that allows unauthorized disclosure of sensitive information in Citrix NetScaler ADC and NetScaler Gateway appliances. When these appliances are configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) or AAA virtual server, a buffer overflow flaw can be exploited to leak sensitive data. This vulnerability allows attackers to read sections of memory beyond the intended buffer, potentially exposing session tokens and enabling impersonation of legitimate users. Exploitation has been observed in the wild, with some attackers using it to bypass multi-factor authentication and hijack user sessions. This vulnerability affects specific versions of NetScaler ADC and NetScaler Gateway, including versions 14.1 before 14.1-8.50, 13.1 before 13.1-49.15, and 13.0 before 13.0-92.19. Citrix-managed cloud services and Citrix-managed Adaptive Authentication are not affected. The vulnerability was publicly disclosed by Citrix on October 10, 2023, and has since been added to CISA's Known Exploited Vulnerabilities Catalog due to observed exploitation.

Description: Sensitive information disclosure in NetScaler ADC and NetScaler Gateway when configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) or AAA  virtual server.
Source: secure@citrix.com
NVD status: Analyzed

Insights

Analysis from the Intruder Security Team

Published Oct 15, 2024

The NetScaler suite of products includes load balancing, firewall and VPN services, so one possible impact is compromised remote access to your private networks. NetScaler responds to certain requests by dumping memory back to the sender, which can contain access tokens for logged in users. The exploit is as bad as whatever you’ve given access to remotely through your NetScaler system. And because they're logged in sessions, MFA won't protect you.

More information is available in our blog post here.

Risk scores

CVSS 3.1

Type: Primary
Base score: 7.5
Impact score: 3.6
Exploitability score: 3.9
Vector string: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Severity: HIGH

Known exploits

Data from CISA

Vulnerability name: Citrix NetScaler ADC and NetScaler Gateway Buffer Overflow Vulnerability
Exploit added on: Oct 18, 2023
Exploit action due: Nov 8, 2023
Required action: Apply mitigations and kill all active and persistent sessions per vendor instructions [https://www.netscaler.com/blog/news/cve-2023-4966-critical-security-update-now-available-for-netscaler-adc-and-netscaler-gateway/] OR discontinue use of the product if mitigations are unavailable.

Weaknesses

secure@citrix.com: CWE-119
nvd@nist.gov: NVD-CWE-noinfo

Hype score: Not currently trending

Configurations

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References

Sources include official advisories and independent security research.