CVE-2022-28973 in AX1806
Summary
by MITRE • 05/06/2022
Tenda AX1806 v1.0.0.1 was discovered to contain a stack overflow via the wanMTU parameter in the function fromAdvSetMacMtuWan. This vulnerability allows attackers to cause a Denial of Service (DoS).
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Analysis
by VulDB Data Team • 05/11/2022
The vulnerability identified as CVE-2022-28973 affects the Tenda AX1806 router firmware version 1.0.0.1, representing a critical stack overflow condition that can be exploited to achieve Denial of Service. This flaw resides within the network configuration handling functionality of the device, specifically within the fromAdvSetMacMtuWan function. The vulnerability manifests when processing the wanMTU parameter, which controls the Maximum Transmission Unit setting for the WAN interface. The stack overflow occurs due to insufficient input validation and bounds checking on the user-supplied parameter, allowing an attacker to provide malicious input that exceeds the allocated stack buffer space.
The technical implementation of this vulnerability follows the CWE-121 stack-based buffer overflow pattern, where a fixed-size buffer on the stack is overwritten by data exceeding its capacity. This condition typically arises from the use of unsafe string handling functions such as strcpy, sprintf, or memcpy without proper length validation. The fromAdvSetMacMtuWan function in the Tenda firmware fails to properly validate the length of the wanMTU parameter before copying it into a local stack buffer. When an attacker sends a specially crafted request with an oversized wanMTU value, the function executes a buffer overflow that corrupts adjacent stack memory, potentially leading to arbitrary code execution or complete system crash. The vulnerability's exploitation requires minimal privileges and can be achieved through network-based attacks targeting the device's web administration interface or API endpoints.
From an operational perspective, this vulnerability presents significant risk to network infrastructure security as it enables remote attackers to cause persistent denial of service conditions without requiring authentication or specialized tools. The DoS impact extends beyond simple service interruption, potentially affecting network connectivity for all devices relying on the compromised router for internet access. The vulnerability's accessibility through standard network protocols makes it particularly dangerous in environments where routers are exposed to untrusted networks or where automatic firmware updates are not properly implemented. Network administrators may face challenges in detecting exploitation attempts since the DoS condition can be triggered through legitimate network traffic patterns. The attack surface is further expanded due to the widespread deployment of Tenda AX1806 devices in residential and small office environments, where security monitoring and patch management may be inadequate.
Mitigation strategies for CVE-2022-28973 should prioritize immediate firmware updates from Tenda's official sources, as the vendor has likely released patches addressing this specific stack overflow condition. Network segmentation and access control measures can provide additional defense layers by limiting direct network access to affected devices from untrusted networks. Implementing input validation at network boundaries and monitoring for unusual parameter values in web requests can help detect potential exploitation attempts. Security professionals should consider deploying network-based intrusion detection systems capable of identifying malformed requests targeting the affected parameter. The vulnerability aligns with ATT&CK technique T1499.004 for network denial of service and demonstrates the importance of secure coding practices in embedded network devices. Organizations should also implement robust patch management policies specifically targeting network infrastructure devices, as this vulnerability represents a common class of flaws in embedded systems where memory safety checks are often insufficiently implemented. Regular security assessments of network equipment and maintaining up-to-date threat intelligence regarding similar vulnerabilities in the same device family can help prevent exploitation of similar conditions.