CVE-2023-20269
Cisco ASA and FTD Software Remote Access VPN Unauthorized Access Vulnerability
DESCRIPTION
CVE-2023-20269 is a vulnerability in Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) software that affects the remote access VPN feature. Such vulnerabilities are often targeted by cybercriminals as there are no updates or protective measures available when the vulnerability is first discovered.
This zero-day vulnerability has been exploited in real-world attacks, meaning attackers have used it to exploit systems using Cisco's ASA and FTD products. This poses a serious threat as cybercriminals have taken active steps to exploit this vulnerability.
Two cybercriminal groups, LockBit and Akira, have been associated with exploiting this vulnerability. They are well-known groups in the cybercrime world, often encrypting their victims' data and demanding ransom for decryption. They use ransomware attacks to extort money from their victims.
This vulnerability is an unauthorized access issue. In other words, through this vulnerability, attackers can attempt to access vulnerable ASA or FTD devices without proper authorization.
Unauthenticated attackers from vulnerable devices can exploit this vulnerability in two ways:
1. Performing brute force attacks on usernames and passwords for vulnerable systems.
2. Using valid credentials to establish clientless SSL VPN sessions with unauthorized users.
Due to its serious potential impact, this vulnerability has a high severity score on the severity scale at nvd.nist.gov, which is 9.1 (Critical) Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.
AFFECTED SYSTEMS
This vulnerability specifically affects the Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) software. The vulnerable versions for the Adaptive Security Appliance (ASA) are version 9.16 and earlier.
VULNERABILITY IMPACT
The CVE-2023-20269 vulnerability in Cisco ASA and FTD devices has the potential for serious impact on affected organizations and systems. The impacts of this vulnerability can include:
• Unauthorized Access to Systems: This vulnerability can allow attackers to gain unauthorized access to vulnerable Cisco ASA or FTD devices. This means attackers can access or control systems without proper authorization.
• Potential Ransomware Attacks: As mentioned earlier, ransomware groups like LockBit and Akira have exploited this vulnerability. The impact could be ransomware infections that encrypt critical data on infected devices or networks, followed by demands for ransom payments to obtain decryption keys.
• Financial Loss: Ransomware attacks that may occur as a result of this vulnerability can lead to significant financial losses, both in terms of ransom payments and long-term impacts such as data loss or reputation damage.
To mitigate the impact of this vulnerability, it is crucial to take the actions recommended by Cisco promptly, including implementing the temporary security measures (workarounds) they have provided and carefully monitoring the situation until official patches are available. Additionally, enabling Multi-Factor Authentication (MFA) for VPN users is highly recommended to enhance security.
RECOMMENDATIONS
While there is no method to completely prevent brute force attack attempts, you can implement the following recommendations to limit the impact of brute force attacks and to protect against unauthorized Clientless SSL VPN session creation using the DefaultADMINGroup or DefaultL2LGroup connection/profile tunnel group:
1. Implement a strong password policy: Enforce complex passwords for all user accounts, including VPN accounts, to make it more difficult for attackers to guess or crack passwords.
2. Enable account lockout policies: Implement account lockout policies that temporarily lock out user accounts after a certain number of failed login attempts. This can help mitigate the impact of brute force attacks by preventing attackers from making unlimited login attempts.
3. Monitor and log authentication attempts: Monitor and log authentication attempts to identify and respond to suspicious or malicious login activity. Analyzing authentication logs can help detect and mitigate brute force attacks in real-time.
4. Use multi-factor authentication (MFA): Implement multi-factor authentication (MFA) for VPN authentication to add an extra layer of security. MFA requires users to provide additional authentication factors, such as a one-time passcode sent to their mobile device, in addition to their password, making it more difficult for attackers to compromise accounts through brute force attacks.
For detailed recommendations and workarounds, refer to the following link: Cisco Security Advisory