CVE-2022-20845 - Memory Leak Vulnerability in Cisco NCS 400 Series TL1 Function: Exploit Details, Code Snippets, and Mitigation Measures

The recently discovered memory leak vulnerability (CVE-2022-20845) in the TL1 function of the Cisco Network Convergence System (NCS) 400 Series has raised concerns within the cyber security community. This vulnerability is attributed to the improper handling of memory allocation in the TL1 process. An authenticated, local attacker could exploit this vulnerability by connecting to the device and issuing TL1 commands, ultimately causing a denial of service (DoS). This post delves into the details of this vulnerability, the code snippets associated with it, and the available patch from Cisco to address the issue.

Code Snippet

A rudimentary code snippet demonstrating an attack exploiting this vulnerability would involve connecting to the device's console, authenticating, and issuing TL1 commands that drain memory resources. The sample code snippet might look like this:

import socket
import sys

# Connect to the device
def connect(host, port):
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    s.connect((host, port))
    return s

# Authenticate with the device
def authenticate(s, username, password):
    s.send("login:{}:{};".format(username, password))

# Issue TL1 commands to consume memory resources
def exploit(s):
    while True:
        s.send("exploit_command_here;")
if __name__ == '__main__':
    host = sys.argv[1]
    port = int(sys.argv[2])
    username = sys.argv[3]
    password = sys.argv[4]

    s = connect(host, port)
    authenticate(s, username, password)
    exploit(s)

Exploit Details

The TL1 function in the Cisco NCS 400 Series fails to free up memory in some situations, paving the way for attackers to exploit it. Once authenticated, an attacker can connect to the device and issue TL1 commands, resulting in the TL1 process consuming significant amounts of memory. When the memory usage exceeds a specific threshold, the Resource Monitor (Resmon) process will start restarting or shutting down the top five consumers of memory, leading to a DoS scenario.

Original References

The original security advisory for this vulnerability can be found at Cisco Security Advisory, which provides a comprehensive list of advisories related to the September 2022 release of the Cisco IOS XR Software Security Advisory Bundled Publication.

Mitigation Measures

Cisco has released software updates to address this vulnerability. Administrators are encouraged to apply these updates immediately and regularly review their security posture. There are no workarounds that address this vulnerability.

For a complete list of advisories and links to them, see the Cisco IOS XR Software Security Advisory Bundled Publication.

In conclusion, the CVE-2022-20845 vulnerability represents a significant threat to organizations utilizing the Cisco NCS 400 Series, as it has the potential to cause a DoS. Therefore, it is of utmost importance for network administrators to stay informed and apply the necessary patches and updates to mitigate this vulnerability.

Timeline

Published on: 11/15/2024 16:15:22 UTC
Last modified on: 11/18/2024 17:11:56 UTC