CVE-2022-20928 - Authentication and Authorization Vulnerability in Cisco ASA and FTD VPN Software

A recently discovered vulnerability, CVE-2022-20928, affecting the authentication and authorization processes in Cisco Adaptive Security Appliance (ASA) Software and Firepower Threat Defense (FTD) Software can potentially allow an unauthenticated, remote attacker to establish a VPN connection under a different user's access privileges. This poses a high security risk, as it opens up possibilities for unauthorized access to sensitive data and resources. As a result, this issue must be addressed immediately to ensure the security of VPN connections and the entire network infrastructure.

Description of the Vulnerability

The vulnerability stemmed from a flaw in the authorization verification process during the VPN authentication flow. An attacker could exploit this vulnerability by sending a specially crafted packet during the VPN authentication process. However, the attacker must have valid credentials to establish a VPN connection in the first place. Once they successfully exploit the vulnerability, the attacker could establish a VPN connection that is granted access privileges belonging to another user.

Code Snippet

In a hypothetical scenario, the attacker might use the following code snipplet to initiate this exploit, sending a crafted packet during the VPN authentication process:

import requests
# Attacker's valid VPN credentials
username = "attacker_username"
password = "attacker_password"

# VPN endpoint URL
url = "https://vpn.example.com/authenticate";

# Crafted packet to exploit vulnerability
payload = {
    'vpn-username': username,
    'vpn-password': password,
    'vpn-targetUser': 'different_user'
}

# Exploit the vulnerability by sending the crafted packet
response = requests.post(url, data=payload)

# Establish a VPN connection with different user's access privileges
if response.status_code == 200:
    print("Exploit successful")
else:
    print("Exploit failed")

For more information about this vulnerability, you can refer to the following resources

1. Cisco Adaptive Security Appliance Software and Firepower Threat Defense Software SSL VPN Authentication and Authorization Vulnerability
Link: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/ASA_SSL_VPN_Auth_Bypass

Common Vulnerabilities and Exposures (CVE) reference

Link: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-20928

Exploit Details

The severity of this vulnerability lies in the attacker's ability to escalate their privileges by establishing a VPN connection that grants them access to resources that they shouldn't normally have access to. This can lead to unauthorized data access, tampering of information, and further intrusion into the protected network. As an organization, it is crucial to apply necessary security patches or implement appropriate workaround solutions to address this vulnerability and ensure the safety of your VPN and network infrastructure.

Conclusion

The CVE-2022-20928 vulnerability is a serious security risk in Cisco ASA and FTD VPN connection software that could potentially grant an attacker with valid credentials, escalated privileges, enabling unauthorized access to sensitive data and resources. It is highly recommended to stay informed of the latest security updates and patches from Cisco or other relevant security vendors, as well as implementing proper security measures to mitigate this vulnerability and protect the integrity of your organization's network.

Timeline

Published on: 11/15/2022 21:15:00 UTC
Last modified on: 11/21/2022 15:08:00 UTC