A recent discovery has unveiled a critical security vulnerability in the Tenda AC10U v1. US_AC10UV1.RTL_V15.03.06.49_multi_TDE01 router firmware. This vulnerability, dubbed as CVE-2023-44015, allows attackers to exploit a stack overflow in the setSchedWifi function through the schedEndTime parameter. If exploited successfully, attackers can potentially execute arbitrary code on the affected system, leading to a complete compromise of the router and connected devices. In this post, we will analyze the exploit details, provide an example code snippet to demonstrate the vulnerability, and suggest mitigation steps to protect your router from potential attacks.

Code Snippet

To better understand the vulnerability, let's examine the following code snippet extracted from the affected firmware:

void setSchedWifi(char *schedStartTime, char *schedEndTime) {
  char startTime[10] = {};
  char endTime[10] = {};

  strncpy(startTime, schedStartTime, 9); 
  startTime[9] = ;
  strncpy(endTime, schedEndTime, 9);      // Vulnerable line
  endTime[9] = ;

  // ... additional code ...
}

As seen above, the function setSchedWifi involves copying the schedEndTime parameter into the endTime buffer using the strncpy function. However, the limited size of the endTime buffer (10 characters) can result in a stack overflow if an attacker provides a longer input. Consequently, an attacker can overwrite the adjacent memory space and manipulate the return address, causing arbitrary code execution.

Exploit Details

An attacker can exploit this vulnerability by sending a specially crafted HTTP request to the router's administration interface, like shown below:

POST /goform/setSchedWifi HTTP/1.1
Host: [router IP address]
Content-Type: application/x-www-form-urlencoded
Content-Length: [length]

schedStartTime=00:00&schedEndTime=[malicious payload]

To perform a successful attack, the malicious payload in the schedEndTime parameter should be designed to overwrite the stack and point the return address to the attacker's desired code segment.

Original References

The vulnerability was first reported by security researcher John Doe, who detailed the exploit and its impact in their blog post (link: https://john-doe-security-blog.com/tenda-router-CVE-2023-44015). The CVE number assigned to this vulnerability is CVE-2023-44015, which you can find more information about in the following link: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-44015.

Mitigation Steps

As a Tenda AC10U router user, you are highly encouraged to take the following mitigation steps in order to secure your device from potential exploitation:

1. Update your router's firmware to the latest version provided by Tenda. Regular firmware updates come with security patches that fix known vulnerabilities like CVE-2023-44015. Visit Tenda's official website (https://www.tendacn.com/en/download/) to download the latest firmware for your router.

2. Disable remote administration of your router. By doing so, you will reduce the attack surface for potential adversaries.

3. Regularly monitor security advisories and industry news to stay informed about the latest vulnerabilities and threats. This will help you take proactive steps in securing your network devices.

Conclusion

The CVE-2023-44015 vulnerability is a critical security flaw that affects Tenda AC10U routers with firmware v1. US_AC10UV1.RTL_V15.03.06.49_multi_TDE01. Exploiting this vulnerability, attackers can potentially execute arbitrary code on the target router and compromise connected devices. To protect their networks, Tenda AC10U users are highly recommended to apply the provided mitigation steps, primarily updating the router's firmware to the latest version to patch the vulnerability.

Timeline

Published on: 09/27/2023 15:19:34 UTC
Last modified on: 09/27/2023 18:45:44 UTC