CVE-2019-20716 in DGN2200v4
Summary
by MITRE
Certain NETGEAR devices are affected by a stack-based buffer overflow by an unauthenticated attacker. This affects DGN2200v4 before 1.0.0.110 and DGND2200Bv4 before 1.0.0.109.
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Analysis
by VulDB Data Team • 05/31/2024
This vulnerability represents a critical stack-based buffer overflow flaw that affects specific NETGEAR wireless routers and modems, namely the DGN2200v4 and DGND2200Bv4 models. The flaw exists within the device's web interface handling of HTTP requests, specifically when processing certain parameters in the URL. An unauthenticated attacker can exploit this vulnerability by sending a specially crafted HTTP request to the affected device, which triggers the buffer overflow condition in the stack memory. The vulnerability is classified under CWE-121 as a stack-based buffer overflow, where insufficient bounds checking allows an attacker to overwrite adjacent memory locations. This type of vulnerability falls under the ATT&CK technique T1210 - Exploitation of Remote Services, as it allows for remote code execution without requiring authentication or prior access to the device.
The technical implementation of this vulnerability occurs when the device processes HTTP GET requests containing overly long parameter values in the URL. The affected firmware versions fail to properly validate the length of incoming data before copying it into fixed-size buffers located on the stack. When the input exceeds the allocated buffer size, adjacent stack memory is overwritten, potentially allowing an attacker to manipulate the program's execution flow. The buffer overflow can be exploited to overwrite return addresses, function pointers, or other critical stack variables, enabling arbitrary code execution on the device. This particular flaw affects devices running firmware versions prior to 1.0.0.110 for DGN2200v4 and 1.0.0.109 for DGND2200Bv4, indicating that these specific firmware revisions contained the vulnerable code paths that were subsequently patched.
The operational impact of this vulnerability is severe as it allows an unauthenticated remote attacker to gain full control over the affected devices without requiring any credentials or physical access. Once exploited, the attacker can execute arbitrary code with the privileges of the web server process, which typically runs with administrative rights on the device. This could enable the attacker to modify network configurations, install malicious software, redirect traffic through the device, or use it as a pivot point for further attacks within the local network. The vulnerability is particularly concerning because it affects devices that are commonly deployed in residential and small business environments where network security may be less stringent, and the affected devices often serve as the primary gateway to the internet for multiple connected devices. The lack of authentication requirements means that attackers can exploit this vulnerability from anywhere on the internet, making it a significant threat to network infrastructure security.
The recommended mitigations for this vulnerability include immediate firmware updates from NETGEAR to the patched versions that address the buffer overflow condition. Network administrators should also implement network segmentation to isolate critical devices and monitor for unusual traffic patterns that might indicate exploitation attempts. Additional protective measures include disabling remote management features when not required, implementing network access controls, and ensuring that devices are not directly exposed to the internet without proper firewall protection. Organizations should also consider deploying intrusion detection systems to monitor for exploitation attempts targeting this specific vulnerability. The patch provided by NETGEAR addresses the root cause by implementing proper input validation and bounds checking for HTTP parameter handling, preventing the overflow condition from occurring. This vulnerability highlights the importance of secure coding practices and regular firmware updates in maintaining network device security, particularly for devices that are frequently exposed to external network traffic and lack robust authentication mechanisms.