In late 2022, Cisco announced a critical security issue in its Smart Software Manager On-Prem (Cisco SSM On-Prem) product. Tracked as CVE-2022-20939, this vulnerability made it possible for authenticated attackers to elevate their privileges just by looking at specific log files.

Let's break down how it works, why it matters, and what you should do if you use Cisco SSM On-Prem.

What Is CVE-2022-20939?

CVE-2022-20939 is a vulnerability in the web-based management interface of Cisco Smart Software Manager On-Prem. The issue is caused by inadequate protection of sensitive user information in log files.

Attackers can extract admin-privileged information from logs and become system admin.

> No workarounds exist for this vulnerability—only updating Cisco's software will secure your system.

How Does the Vulnerability Work?

Simply put:
Cisco SSM On-Prem's web management interface writes sensitive information into its logs. If a regular user logs in and can access these logs, they may find system admin credentials or tokens by sifting through the log data.

Proof-of-Concept Code

Here's a simplified Python code snippet showing how such an exploit might look. Note: This is illustrative only; real-life logs may differ.

# Example exploit reading log files for admin tokens

with open('/opt/cisco/ssm/logs/ssm.log', 'r') as logfile:
    for line in logfile:
        # Look for lines containing the admin token (simple pattern)
        if 'admin_token' in line:
            token_line = line.strip()
            # Extract token, assuming: "admin_token: <token_value>"
            admin_token = token_line.split('admin_token: ')[-1]
            print(f"Found admin token: {admin_token}")

# Use the token in future admin API requests... (outside scope for safety)

Download or view log files from the system's web file viewer, SFTP, or terminal (if allowed).

3. Search for admin tokens/credentials.

Exploitation Example

Imagine Alice has "viewer" access to Cisco SSM On-Prem. She wants admin access. Here's how she might exploit CVE-2022-20939:

Alice logs in as herself.

2. She goes to the "Logs" section or accesses /opt/cisco/ssm/logs/ssm.log (location may vary).

The system accepts her as "System Admin."

That's how easy privilege escalation can be with this vulnerability.

Update your Cisco Smart Software Manager On-Prem to the latest version as soon as possible.

- Check Cisco's official advisory for detailed information and updates.

References

- Cisco Security Advisory for CVE-2022-20939 (Official)
- CVE Report for CVE-2022-20939

Summary

CVE-2022-20939 is a high-impact privilege escalation vulnerability that affects Cisco Smart Software Manager On-Prem. It allows any authenticated user to become a system admin by harvesting sensitive info from unsafe log files. No temporary fixes exist—update immediately.

Timeline

Published on: 11/15/2024 15:25:32 UTC