Actively exploited in the wild
Cisco Adaptive Security Appliance and Firepower Threat Defense Unauthorized Access Vulnerability
Cisco - Adaptive Security Appliance and Firepower Threat Defense · Listed in the CISA KEV since 2023-09-13. This indicates confirmed attacks in production environments.
Required action: Apply mitigations per vendor instructions for group-lock and vpn-simultaneous-logins or discontinue use of the product for unsupported devices.
CVE-2023-20269
MediumCVSS 5.0KEVExploitation Probability (EPSS)
Very high risk97th percentile - higher than 97% of all known CVEs
Summary
A vulnerability in the remote access VPN feature of Cisco ASA and Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to conduct a brute force attack to identify valid credentials or an authenticated, remote attacker to establish a clientless SSL VPN session with an unauthorized user. The issue is due to improper separation of authentication, authorization, and accounting (AAA) between the remote access VPN feature and the HTTPS management and site-to-site VPN features.
Risk Assessment
An attacker could obtain valid credentials, potentially leading to unauthorized VPN access to the network, and on older software versions (9.16 and earlier) also establish a clientless SSL VPN session. This could expose the organization to unauthorized access to internal resources and security breaches.
Recommendation
Apply available Cisco ASA/FTD software updates once released and consider implementing the workarounds described by the vendor. Additionally, enable multi-factor authentication (MFA) and monitor logs for unusual VPN login attempts.
Original NVD description (English source)
A vulnerability in the remote access VPN feature of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to conduct a brute force attack in an attempt to identify valid username and password combinations or an authenticated, remote attacker to establish a clientless SSL VPN session with an unauthorized user. This vulnerability is due to improper separation of authentication, authorization, and accounting (AAA) between the remote access VPN feature and the HTTPS management and site-to-site VPN features. An attacker could exploit this vulnerability by specifying a default connection profile/tunnel group while conducting a brute force attack or while establishing a clientless SSL VPN session using valid credentials. A successful exploit could allow the attacker to achieve one or both of the following: Identify valid credentials that could then be used to establish an unauthorized remote access VPN session. Establish a clientless SSL VPN session (only when running Cisco ASA Software Release 9.16 or earlier). Notes: Establishing a client-based remote access VPN tunnel is not possible as these default connection profiles/tunnel groups do not and cannot have an IP address pool configured. This vulnerability does not allow an attacker to bypass authentication. To successfully establish a remote access VPN session, valid credentials are required, including a valid second factor if multi-factor authentication (MFA) is configured. Cisco will release software updates that address this vulnerability. There are workarounds that address this vulnerability.