CVE-2022-30477 in AC18
Summary
by MITRE • 05/26/2022
Tenda AC Series Router AC18_V15.03.05.19(6318) was discovered to contain a stack-based buffer overflow in the httpd module when handling /goform/SetClientState request.
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Analysis
by VulDB Data Team • 06/01/2022
The vulnerability identified as CVE-2022-30477 affects Tenda AC Series routers running firmware version AC18_V15.03.05.19(6318) and potentially other models within the AC series. This represents a critical security flaw that resides within the httpd web server module of the router's firmware, specifically in how it processes incoming HTTP requests. The vulnerability manifests when the router receives a crafted request to the /goform/SetClientState endpoint, which is typically used for managing client device states within the router's wireless network configuration. The affected firmware implementation fails to properly validate input parameters, creating an exploitable condition that allows attackers to manipulate memory structures through carefully crafted payloads.
The technical nature of this vulnerability constitutes a stack-based buffer overflow, which falls under CWE-121, specifically categorized as a buffer overflow in the stack data structure. This flaw occurs because the router's httpd module does not enforce proper bounds checking on user-supplied data received through the SetClientState API endpoint. When a maliciously crafted HTTP request is sent to the router, the data is copied into a fixed-size buffer on the stack without adequate validation of the input length. This allows an attacker to overwrite adjacent memory locations, potentially including return addresses and other critical stack variables. The vulnerability is particularly concerning because it operates at the application layer of the network stack, making it accessible through standard HTTP communications that routers typically accept from both local and remote sources.
The operational impact of this vulnerability extends beyond simple denial of service conditions, as it presents a significant attack surface that could enable remote code execution on affected devices. An attacker who successfully exploits this buffer overflow could potentially gain unauthorized access to the router's administrative functions, allowing them to modify network configurations, disable security features, or establish persistent backdoors. The vulnerability affects the router's core functionality since the httpd module is responsible for processing all web-based administrative requests, meaning that exploitation could occur through any web browser interface that communicates with the router's management port. This creates a persistent threat vector that remains active as long as the vulnerable firmware is installed, potentially allowing attackers to maintain long-term access to the network infrastructure.
Mitigation strategies for this vulnerability should prioritize immediate firmware updates from Tenda, as the manufacturer would have likely released patches addressing the specific buffer overflow condition in the httpd module. Network administrators should implement network segmentation and access controls to limit exposure of these devices to untrusted networks, while also monitoring for unusual traffic patterns that might indicate exploitation attempts. Security professionals should consider implementing intrusion detection systems that can identify malformed requests to the /goform/SetClientState endpoint, as these would be characteristic of exploitation attempts. The vulnerability aligns with ATT&CK technique T1072, which covers software deployment methods, particularly when attackers attempt to establish persistence through router configuration modifications. Organizations should also conduct thorough network inventory assessments to identify all affected Tenda devices and implement proper network access controls to prevent unauthorized access to administrative interfaces. Regular security audits of network infrastructure should include verification of firmware versions and patch status to ensure that known vulnerabilities like CVE-2022-30477 remain properly addressed.