CVE-2021-45523 in R7000
Summary
by MITRE • 12/26/2021
NETGEAR R7000 devices before 1.0.9.42 are affected by a buffer overflow by an authenticated user.
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Analysis
by VulDB Data Team • 12/28/2021
The vulnerability identified as CVE-2021-45523 affects NETGEAR R7000 wireless routers running firmware versions prior to 1.0.9.42. This represents a critical buffer overflow flaw that can be exploited by authenticated users within the local network, potentially leading to remote code execution and complete system compromise. The vulnerability resides in the device's web interface handling of user input, specifically in how the router processes certain parameters sent through HTTP requests.
This buffer overflow vulnerability stems from inadequate input validation and bounds checking within the router's web server component. When an authenticated user submits maliciously crafted data through the web interface, the application fails to properly validate the length of input parameters, allowing an attacker to overwrite adjacent memory locations in the router's process space. The flaw is classified as a CWE-121 stack-based buffer overflow, where insufficient bounds checking enables memory corruption that can be leveraged to execute arbitrary code. The vulnerability is particularly concerning because it requires only local network authentication, meaning that an attacker with valid credentials for the router can exploit this flaw without requiring physical access or additional network privileges.
The operational impact of this vulnerability extends beyond simple denial of service scenarios. An authenticated attacker can potentially gain full administrative control over the affected router, enabling them to modify network configuration settings, redirect traffic through malicious proxies, intercept and modify network communications, or establish persistent backdoors for future access. The compromised device can serve as a pivot point for lateral movement within the network, allowing attackers to scan internal systems, launch attacks against other devices, or use the router as a command and control server. This aligns with ATT&CK technique T1071.004 for application layer protocol tunneling and T1059.001 for command and script interpreter execution.
Mitigation strategies for CVE-2021-45523 should prioritize immediate firmware updates to version 1.0.9.42 or later, which contain patches addressing the buffer overflow conditions. Network administrators should also implement additional security controls including disabling unnecessary services, implementing strict access controls for router management interfaces, and monitoring for unusual network behavior that might indicate exploitation attempts. The vulnerability highlights the importance of secure coding practices and input validation, particularly for web applications running on embedded devices. Organizations should conduct regular security assessments of their network infrastructure, maintain up-to-date inventory of all connected devices, and implement network segmentation to limit the potential impact of such vulnerabilities. The flaw also underscores the need for robust firmware update mechanisms and the importance of keeping network devices current with security patches to prevent exploitation of known vulnerabilities.