CVE-2018-21163 in DGN2200Bv4
Summary
by MITRE
Certain NETGEAR devices are affected by a stack-based buffer overflow by an authenticated user. This affects DGN2200Bv4 before 1.0.0.102, DGN2200v4 before 1.0.0.102, EX3700 before 1.0.0.70, EX3800 before 1.0.0.70, EX6000 before 1.0.0.30, EX6100 before 1.0.2.22, EX6120 before 1.0.0.40, EX6130 before 1.0.0.22, EX6150 before 1.0.0.38, EX6200 before 1.0.3.86, EX7000 before 1.0.0.64, R6300v2 before 1.0.4.22, R6900P before 1.3.0.18, R7000P before 1.3.0.18, R7300DST before 1.0.0.62, R7900P before 1.3.0.10, R8000 before 1.0.4.12, R8000P before 1.3.0.10, WN2500RPv2 before 1.0.1.52, and WNDR3400v3 before 1.0.1.18.
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Analysis
by VulDB Data Team • 10/12/2020
This vulnerability represents a critical stack-based buffer overflow flaw that affects multiple NETGEAR networking devices, specifically targeting the web management interface of affected models. The issue stems from inadequate input validation within the device's firmware, allowing authenticated users to exploit a memory corruption vulnerability through crafted HTTP requests. The vulnerability is classified under CWE-121 as a stack-based buffer overflow, which occurs when more data is written to a buffer located on the stack than the buffer can accommodate, leading to potential memory corruption and arbitrary code execution. The affected devices include various router models from different product lines including the DGN2200 series, EX series, R series, and WNDR3400v3, all sharing a common firmware vulnerability that stems from improper bounds checking in the web server component.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it provides authenticated attackers with the capability to execute arbitrary code on affected devices with the privileges of the web server process. This represents a significant escalation from typical network device vulnerabilities, as it allows for complete system compromise and potential lateral movement within network environments. The attack vector requires an authenticated user, meaning that an attacker would need valid credentials to access the device's web management interface before exploiting this vulnerability. However, in enterprise environments where default credentials are often left unchanged or where credential management is inadequate, this requirement becomes less restrictive. The vulnerability affects firmware versions prior to specific patches, indicating that NETGEAR released targeted updates to address this issue, though the affected device range suggests a widespread problem across multiple product families.
Network security professionals should recognize this vulnerability as a prime example of how embedded systems in network infrastructure can contain critical flaws that persist across multiple generations of hardware. The attack surface is particularly concerning because routers serve as central points in network architectures, and compromising their management interfaces can provide attackers with persistent access to entire network segments. This vulnerability aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as exploitation could enable attackers to execute commands on the compromised device. The security implications extend to potential credential theft, network reconnaissance, and establishment of persistent backdoors that could remain undetected for extended periods. Organizations should implement immediate mitigation strategies including firmware updates, network segmentation, and monitoring for suspicious authentication attempts to prevent exploitation of this vulnerability.
The technical nature of this vulnerability demonstrates how embedded device firmware development often lacks the rigorous security testing applied to enterprise software, resulting in memory corruption issues that can be exploited by attackers with minimal privileges. The stack-based nature of the overflow indicates that the vulnerability likely occurs in functions handling user input through HTTP parameters, where insufficient bounds checking allows attackers to overwrite stack memory. This pattern is consistent with classic buffer overflow vulnerabilities that have plagued embedded systems for decades, highlighting the need for secure coding practices throughout the entire development lifecycle of network equipment. Security teams should prioritize patching affected devices, as the window for exploitation is relatively small since the vulnerability requires authentication, but the potential impact of successful exploitation makes it a critical priority for remediation.