Executive Summary

This vulnerability is a stack-based buffer overflow in the Tenda AC20 router firmware version 16.03.08.12. It occurs in the function formSetRebootTimer within the /goform/SetSysAutoRebbotCfg endpoint of the httpd component. By manipulating the rebootTime parameter with crafted input, an attacker can overflow the stack buffer. This flaw allows remote attackers to potentially cause denial-of-service or execute arbitrary commands on the device without authentication. [1, 2]

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Impact Analysis

Exploitation of this vulnerability can impact the confidentiality, integrity, and availability of the affected device. An attacker can remotely cause denial-of-service conditions or execute arbitrary commands, potentially taking full control of the router. This can disrupt network operations and compromise sensitive data passing through the device. [1, 2]

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Detection Guidance

Detection can be performed by monitoring HTTP requests to the /goform/SetSysAutoRebbotCfg endpoint on Tenda AC20 routers running firmware version 16.03.08.12, specifically looking for suspicious or unusually large rebootTime parameter values that could trigger the stack-based buffer overflow. Network intrusion detection systems (NIDS) can be configured to alert on such requests. Additionally, reviewing logs for unexpected reboots or crashes may indicate exploitation attempts. Specific commands are not provided in the resources. [1, 2]

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Mitigation Strategies

Immediate mitigation steps include replacing the affected Tenda AC20 router firmware version 16.03.08.12 with an alternative or updated version if available, as no known countermeasures or patches exist. Limiting remote access to the device and restricting HTTP access to trusted networks may reduce exposure. Monitoring for exploitation attempts and disabling the vulnerable service if possible are also recommended. [2]

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