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Introduction

Recently, a vulnerability known as CVE-2023-20090 was found in Cisco TelePresence CE and RoomOS devices. This weakness can let an attacker who already has access to the system upgrade their permissions to root – basically giving them total control. This post breaks down how the exploit works, shows a simple code example, and provides steps for protection.

What is CVE-2023-20090?

CVE-2023-20090 is a security hole where the command-line interface (CLI) in certain Cisco devices doesn’t properly control access to certain system commands. This means that someone who can log in as a regular user can make themselves a root (superuser) by tricking the device with special commands.

Cisco RoomOS Software

(For the full list, check Cisco Advisory.)

1. What is Privilege Escalation?

Privilege escalation means gaining higher permissions than you should have. In this case, it’s moving from a regular account to the “root” user, who can change or delete anything.

2. How Does the Exploit Work?

- The attacker logs in to the device with a regular account (they must be logged in locally, not over the network).
- Due to improper access control, certain CLI commands that should only be run by the root user are accessible.
- By running a crafted combination of these commands, the attacker’s user account can be given root access.

3. Sample Exploit Scenario

Let’s say you’re logged in as a normal user. You notice that the system doesn’t properly check if you can run certain administrative commands.

Sample Pseudocode

Here’s a Python example showing what a local attacker might do, assuming they have CLI access (*note: don't use this for attacks; this is for education only*). This is a simplified demo:

import os

# Step 1: The attacker has local access as a normal user

# Step 2: They try to run a command meant only for root
cmd = "sudo some_protected_command --args"

# Step 3: Device fails to check access control, so the command works
os.system(cmd)

# Step 4: Attacker verifies root access
os.system("id")  # This should show "uid=(root)"

*In real life, the exact command(s) would depend on the firmware version and internal CLI. The attacker would usually make use of system jobs or poorly protected scripts.*

Fixes & Mitigation

There’s no workaround! You must upgrade your device to the fixed software version.

Download the latest update:

Get the fixed firmware from the Cisco downloads page.

Install the update:

Use Cisco’s official instructions for updating software.

References

- Cisco Security Advisory for CVE-2023-20090
- NVD CVE-2023-20090 Record
- Cisco Upgrading CE/RoomOS Guide (Official)

Conclusion

CVE-2023-20090 is easy to exploit if an attacker already has local access to your TelePresence or RoomOS device. The only way to fix it is a software update. Make sure to stay current with patches to keep your collaboration systems secure!

Let people in your IT department know about this issue and upgrade all at-risk devices today.

*Stay safe and patch early!*

*For exclusive more guides and how-to’s, follow our blog. Need help? Drop us a comment or reach out for support.*

Timeline

Published on: 11/15/2024 16:15:25 UTC