CVE-2021-46263 in AC11
Summary
by MITRE • 02/15/2022
Tenda AC Series Router AC11_V02.03.01.104_CN was discovered to contain a stack buffer overflow in the wifiTime module. This vulnerability allows attackers to cause a Denial of Service (DoS) via crafted overflow data.
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Analysis
by VulDB Data Team • 02/18/2022
The vulnerability identified as CVE-2021-46263 affects Tenda AC Series routers running firmware version AC11_V02.03.01.104_CN and potentially other models within the AC series. This issue resides within the wifiTime module of the router's firmware, representing a critical security flaw that compromises the device's stability and operational integrity. The affected firmware version demonstrates poor input validation practices that fail to properly handle oversized data inputs, creating an exploitable condition that can be leveraged by malicious actors.
The technical flaw manifests as a stack buffer overflow within the wifiTime module, which occurs when the router processes incoming data without adequate bounds checking. This type of vulnerability falls under CWE-121, which specifically addresses stack-based buffer overflow conditions where insufficient boundary checks allow attackers to overwrite adjacent memory locations. The overflow typically occurs when the module receives crafted input data that exceeds the allocated buffer space, causing the program to overwrite adjacent stack variables and potentially leading to arbitrary code execution or system crashes. The vulnerability specifically targets the memory management within the wireless time configuration handling component of the router's web interface.
The operational impact of this vulnerability extends beyond simple denial of service conditions, as it represents a fundamental security weakness that can be exploited to disrupt network services and potentially gain unauthorized access to the device. Attackers can craft malicious payloads that trigger the buffer overflow during normal operation, causing the router to crash and restart continuously, thereby creating persistent denial of service conditions that affect network connectivity for all devices connected to the affected router. This vulnerability directly impacts the availability aspect of the CIA triad and can be classified under the ATT&CK technique T1499.004 for network denial of service attacks.
Mitigation strategies for CVE-2021-46263 should prioritize immediate firmware updates from Tenda to address the buffer overflow condition in the wifiTime module. Network administrators should also implement network segmentation and access controls to limit exposure of affected devices to untrusted networks. Additionally, monitoring network traffic for unusual patterns that might indicate exploitation attempts can help detect potential attacks. The vulnerability highlights the importance of proper input validation and memory management practices in embedded systems, emphasizing the need for regular security assessments of network infrastructure devices. Organizations should also consider implementing network access control measures to prevent unauthorized devices from connecting to their networks and reduce the attack surface for such vulnerabilities.