CVE-2018-21093 in D8500
Summary
by MITRE
Certain NETGEAR devices are affected by a stack-based buffer overflow by an unauthenticated attacker. This affects D8500 before 1.0.3.42, EX3700 before 1.0.0.70, EX3800 before 1.0.0.70, EX6000 before 1.0.0.30, EX6100 before 1.0.2.24, EX6120 before 1.0.0.40, EX6130 before 1.0.0.22, EX6150 before 1.0.0.42, EX6200 before 1.0.3.88, EX7000 before 1.0.0.66, R6250 before 1.0.4.26, R6300-2CXNAS before 1.0.3.60, R6300v2 before 1.0.4.28, R6400 before 1.0.1.36, R6400v2 before 1.0.2.52, R6700 before 1.0.1.46, R6900 before 1.0.1.46, R7000 before 1.0.9.28, R7000P before 1.3.1.44, R6900P before 1.3.1.44, R7100LG before 1.0.0.46, R7300 before 1.0.0.68, R7900 before 1.0.2.10, R8000 before 1.0.4.18, R8000P before 1.3.0.10, R7900P before 1.3.0.10, R8500 before 1.0.2.122, R8300 before 1.0.2.122, RBW30 before 2.1.2.6, WN2500RPv2 before 1.0.0.54, and WNR3500Lv2 before 1.2.0.56.
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Analysis
by VulDB Data Team • 06/03/2024
This vulnerability represents a critical stack-based buffer overflow flaw affecting numerous NETGEAR wireless routers and networking devices, specifically targeting firmware versions prior to the listed secure releases. The issue stems from improper input validation within the device's web interface handling mechanism, where an attacker can craft malicious HTTP requests that exceed the allocated buffer space on the stack. This fundamental memory management error creates an exploitable condition that allows unauthenticated remote code execution, as the overflow can overwrite adjacent memory locations including return addresses and function pointers. The vulnerability affects a broad range of consumer and small office networking equipment, including popular models such as the R6250, R6300v2, R6700, R7000, and various EX series routers, making it particularly concerning for widespread deployment across both residential and commercial networks.
The technical exploitation of this vulnerability follows established patterns described in CWE-121 Stack-based Buffer Overflow, where insufficient bounds checking permits memory corruption that can be leveraged for arbitrary code execution. Attackers can trigger the overflow by sending specially crafted HTTP POST requests to the affected device's web management interface, typically through the HTTP header or form parameters. The unauthenticated nature of this vulnerability means that no prior credentials or network access are required to exploit the flaw, making it extremely dangerous for devices exposed to the internet. This vulnerability directly maps to ATT&CK technique T1203 Exploitation for Client Execution and T1068 Exploitation of Remote Services, as it allows attackers to execute malicious code on the target device without authentication. The buffer overflow can potentially lead to complete device compromise, enabling attackers to gain persistent access to the network, modify device configurations, or use the compromised device as a pivot point for further attacks within the local network.
The operational impact of this vulnerability extends beyond simple device compromise, as affected devices often serve as primary network gateways for residential and small business users. When exploited, these devices can provide attackers with complete control over network traffic, potentially enabling man-in-the-middle attacks, DNS hijacking, or even use as botnet nodes for distributed denial-of-service attacks. The widespread deployment of these affected models across global networks means that a single exploited device can compromise entire local networks, particularly in environments where network segmentation is not properly implemented. Organizations and individuals with these vulnerable devices face significant risk of data breaches, as the compromised devices can serve as entry points for accessing internal network resources, potentially leading to corporate espionage or unauthorized access to sensitive information. The vulnerability also poses risks to network availability, as attackers could potentially cause device crashes or reboots, creating denial-of-service conditions that disrupt network connectivity for legitimate users.
Mitigation strategies for this vulnerability require immediate firmware updates from NETGEAR, as the company has released patches addressing the specific buffer overflow conditions in the affected models. Network administrators should prioritize updating all affected devices to the latest firmware versions, particularly those exposed to external networks or internet-facing interfaces. Additional protective measures include implementing network segmentation to isolate critical systems from potentially compromised devices, disabling unnecessary services and remote management features, and monitoring network traffic for suspicious activity that might indicate exploitation attempts. Organizations should also consider implementing intrusion detection systems that can identify malicious HTTP requests targeting known vulnerable patterns, and establish network access controls that limit external access to router management interfaces. Security teams should conduct comprehensive inventory audits to identify all potentially affected devices within their networks and develop incident response procedures specifically addressing potential exploitation of this vulnerability, as the attack surface extends beyond simple device compromise to include broader network security implications. The vulnerability highlights the critical importance of firmware security updates and proper network segmentation practices in maintaining overall network security posture.