CVE-2018-7561 in Tenda Ac9
Summary
by MITRE
Stack-based Buffer Overflow in httpd on Tenda AC9 devices V15.03.05.14_EN allows remote attackers to cause a denial of service or possibly have unspecified other impact.
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Analysis
by VulDB Data Team • 01/09/2020
The vulnerability identified as CVE-2018-7561 represents a critical stack-based buffer overflow flaw discovered in the httpd service running on Tenda AC9 wireless routers with firmware version V15.03.05.14_EN. This vulnerability resides within the web server component responsible for handling HTTP requests, making it accessible to remote attackers without requiring authentication. The flaw stems from inadequate input validation mechanisms when processing certain HTTP headers or parameters sent to the affected device. The buffer overflow occurs when the httpd service fails to properly bounds-check data received from network requests, allowing maliciously crafted input to overwrite adjacent memory locations on the stack. This type of vulnerability falls under CWE-121 Stack-based Buffer Overflow, which is classified as a fundamental memory safety issue that can lead to arbitrary code execution or system instability. The attack vector is particularly concerning as it enables remote exploitation over the network, making the vulnerability accessible to threat actors worldwide.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially enable more severe compromise scenarios. When exploited successfully, the buffer overflow can cause the httpd service to crash and restart repeatedly, leading to persistent denial of service for legitimate users accessing the router's web interface. However, the potential for more dangerous outcomes exists, as stack corruption can provide attackers with opportunities to inject and execute malicious code within the router's memory space. This could result in complete system compromise, allowing attackers to gain persistent access to the network, modify router configurations, or establish backdoor access points. The vulnerability affects the device's management interface, potentially enabling attackers to manipulate network settings, redirect traffic, or extract sensitive information from the device. Given that many users rely on these routers for home and small office networks, the implications of such a compromise could extend to broader network security and data integrity concerns.
Mitigation strategies for CVE-2018-7561 should focus on immediate firmware updates from Tenda, as the vendor has likely released patches addressing this specific vulnerability. Network administrators should implement network segmentation to limit exposure of these devices to untrusted networks, while also considering disabling unnecessary web management interfaces when not actively required. The implementation of intrusion detection systems can help monitor for suspicious HTTP traffic patterns that may indicate exploitation attempts. Additionally, organizations should conduct comprehensive vulnerability assessments to identify all devices running affected firmware versions and ensure proper network access controls are in place. From a defensive perspective, this vulnerability aligns with ATT&CK technique T1210 Exploitation of Remote Services, highlighting the importance of maintaining up-to-date device firmware and implementing robust network monitoring. The vulnerability also demonstrates the necessity of applying principle of least privilege controls to network infrastructure devices, ensuring that only authorized personnel have access to management interfaces. Regular security audits and vulnerability scanning should be conducted to identify similar flaws in other network equipment, as similar vulnerabilities have been documented in various networking devices, making this an important case study for broader security hygiene practices across enterprise environments.