Attack Chain

1. The attacker identifies a vulnerable Shenzhen Libituo Technology LBT-T300-HW1 device running firmware version 1.2.8 or earlier.
2. The attacker crafts a malicious HTTP request targeting the /apply.cgi endpoint.
3. The HTTP request includes a specially crafted Channel/ApCliSsid argument designed to overflow the buffer in the start_lan function.
4. The vulnerable start_lan function receives the malicious input and attempts to process it without proper bounds checking.
5. The buffer overflow occurs, overwriting adjacent memory regions, including potentially the return address on the stack.
6. The attacker gains control of the program execution flow by overwriting the return address with the address of malicious code.
7. The injected code executes with the privileges of the web server process.
8. The attacker achieves arbitrary code execution, potentially gaining full control of the device.

Impact

Successful exploitation of this vulnerability allows a remote attacker to execute arbitrary code on the affected device. Given that this is a router, this could lead to complete compromise of the device, including the ability to intercept and manipulate network traffic, install malware, or use the device as part of a botnet. Due to the public availability of the exploit, widespread exploitation is possible.

Recommendation

• Apply network intrusion detection system (NIDS) rules to detect and block malicious HTTP requests targeting /apply.cgi with excessively long Channel/ApCliSsid values.
• Deploy the Sigma rule Detect-LBT-T300-HW1-applycgi-buffer-overflow to your SIEM and tune for your environment to identify exploitation attempts.
• Monitor web server logs for suspicious POST requests to /apply.cgi and analyze the length of the Channel/ApCliSsid parameter.