Chunghwa Telecom (CHT) is one of the largest telecommunications companies in Taiwan, offering various services such as broadband, mobile communications, and IPTV. One of the key equipment provided by CHT to its residential and commercial customers is the NOKIA G-040W-Q device, which functions primarily as a wireless router and includes an integrated firewall.

A newly identified security vulnerability (CVE-2023-41355) affects the firewall function of this device, which can be exploited by an unauthenticated remote attacker. In this blog post, we will take an in-depth look at this vulnerability, its potential impact on affected networks, and the steps that can be taken to mitigate the risk.

Vulnerability Details

The CVE-2023-41355 vulnerability specifically involves improper input validation of ICMP (Internet Control Message Protocol) redirect messages in the Chunghwa Telecom NOKIA G-040W-Q Firewall. What does this mean? It means that an attacker can send carefully crafted packets over the internet to target a vulnerable device, bypassing the protective measures in place and gaining unauthorized access to potentially sensitive information.

Once exploited, a malicious actor can modify the network's routing table, causing a denial of service (DoS) attack or leaking sensitive data from the targeted network. This exploitation could disrupt the normal functioning of the affected network, cause service degradation, and lead to unauthorized access to sensitive information.

Here's a simplified version of the exploit code that an attacker could potentially use

import socket
import struct

target_ip = "192.168.1.1" # Target device IP address
source_ip = "192.168.1.2" # Attacker's IP address

# Craft ICMP Redirect packet
icmp_packet = struct.pack("BbHHh", 5, 1, , , )
payload = b"A" * 8
packet = icmp_packet + payload

sock = socket.socket(socket.AF_INET, socket.SOCK_RAW, socket.IPPROTO_ICMP)
sock.sendto(packet, (target_ip, 1))

By using this exploit code, an attacker can construct and send ICMP redirect packets from a custom source IP address and manipulate the routing table of the targeted device.

Original References

- For a detailed description of the CVE-2023-41355 vulnerability, please refer to the NVD (National Vulnerability Database) entry: <https://nvd.nist.gov/vuln/detail/CVE-2023-41355>
- The manufacturer, NOKIA, has acknowledged this vulnerability and released an official security advisory on the issue: <https://www.nokia.com/security-vulnerability/cve-2023-41355>

Exploit Mitigation

To mitigate the risks associated with the CVE-2023-41355 vulnerability, operators and administrators managing NOKIA G-040W-Q devices should take the following steps:

1. Patch: Apply the latest firmware updates provided by the manufacturer. NOKIA has released a patch to address this vulnerability, and all affected devices should be updated as soon as possible.

2. Network Segmentation: Implement network segmentation to limit the exposure of the device to the internet and other potentially untrusted networks.

3. Access Control Lists (ACLs): Implement strict ACL rules on routers and firewalls to filter incoming ICMP redirect messages.

4. Continuous Monitoring: Regularly monitor and analyze network traffic to detect any malicious activities or packets.

5. Review Security Policies: Regularly review and assess the security policies of the organization and make necessary changes to minimize the risk posed by vulnerabilities like CVE-2023-41355.

Conclusion

The CVE-2023-41355 vulnerability highlights the importance of regularly updating and maintaining network devices to protect against emerging threats. By taking a proactive approach to security, operators and administrators can mitigate the risk of potential attacks and protect their organizations from unauthorized access, data leaks, and service disruption. Stay informed, stay vigilant, and stay secure.

Timeline

Published on: 11/03/2023 06:15:07 UTC
Last modified on: 11/13/2023 19:54:23 UTC