The TK_set_deviceModel_req_handle function in the cloud communication component in Guardzilla GZ621W devices with firmware 0.5.1.4 has a Buffer Overflow.
Guardzilla GZ621W devices running firmware 0.5.1.4 are vulnerable to a buffer overflow in the cloud communication component, allowing for potential remote code execution. Successful exploitation could lead to complete device compromise, enabling attackers to gain unauthorized access to the device and potentially the network it resides on, leading to data breaches and surveillance risks.
Step 1: Payload Delivery: The attacker crafts a malicious HTTP request to the Guardzilla GZ621W device. This request targets the cloud communication component, likely over port 80 or 443, depending on the device configuration and the presence of HTTPS. The request includes a specially crafted device model string that is significantly longer than the allocated buffer size within the TK_set_deviceModel_req_handle function.
Step 2: Request Processing: The device receives the malicious HTTP request and passes it to the cloud communication component. The TK_set_deviceModel_req_handle function is invoked to process the request.
Step 3: Buffer Overflow: The TK_set_deviceModel_req_handle function attempts to copy the attacker-controlled device model string into a fixed-size buffer. Due to the lack of bounds checking, the string copy operation overflows the buffer, overwriting adjacent memory locations.
Step 4: Control Hijack: The buffer overflow overwrites critical data, such as function pointers or return addresses. This allows the attacker to control the execution flow of the device.
Step 5: Code Execution: The attacker leverages the overwritten control data to redirect execution to malicious code, potentially injected into the device's memory or located elsewhere on the network. This code could be used to gain remote access, steal data, or further compromise the network.
The vulnerability lies within the TK_set_deviceModel_req_handle function of the Guardzilla GZ621W's cloud communication component. This function is responsible for handling requests related to the device model. The root cause is a buffer overflow due to insufficient bounds checking when processing the device model string. Specifically, the function fails to properly validate the length of the input string before copying it into a fixed-size buffer. An attacker can craft a malicious request containing an overly long device model string, which overwrites adjacent memory locations on the stack or heap. This overwrite can be leveraged to overwrite control data, such as function pointers, leading to arbitrary code execution. The lack of input validation and the use of unsafe string copy functions are the primary contributors to this vulnerability. The specific function likely uses functions like strcpy or memcpy without proper size checks.