CVE-2019-20700 in D6400
Summary
by MITRE
Certain NETGEAR devices are affected by a stack-based buffer overflow by an unauthenticated attacker. This affects D6220 before 1.0.0.44, D6400 before 1.0.0.78, D7000v2 before 1.0.0.51, D8500 before 1.0.3.42, DGN2200v4 before 1.0.0.110, DGND2200Bv4 before 1.0.0.110, 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, EX6150v1 before 1.0.0.42, EX6200 before 1.0.3.88, EX7000 before 1.0.0.66, R6250 before 1.0.4.26, 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, R7900 before 1.0.2.10, R8000 before 1.0.4.12, R8300 before 1.0.2.122, R8500 before 1.0.2.122, R6900P before 1.3.1.64, R7000P before 1.3.1.64, R7100LG before 1.0.0.46, R7300DST before 1.0.0.68, R7900P before 1.3.0.10, R8000P before 1.3.0.10, WN2500RPv2 before 1.0.1.54, WNDR3400v3 before 1.0.1.22, and WNR3500Lv2 before 1.2.0.54.
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Analysis
by VulDB Data Team • 05/27/2024
This vulnerability represents a critical stack-based buffer overflow flaw in multiple NETGEAR router models that allows unauthenticated remote attackers to execute arbitrary code on affected devices. The vulnerability stems from insufficient input validation in the device's web interface handling mechanism, where crafted malicious input can 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 has been a persistent concern in embedded systems and network devices. The flaw specifically affects a wide range of NETGEAR routers including various models from the D-series, EX-series, R-series, and WNR-series, with the affected versions showing a pattern of older firmware releases that lack proper bounds checking mechanisms in their HTTP request processing components.
The technical exploitation of this vulnerability occurs through specially crafted HTTP requests sent to the affected device's web management interface. When an attacker sends a request containing overly long input strings to specific parameters within the web server component, the device fails to properly validate the input length before copying it to a fixed-size stack buffer. This buffer overflow condition can be leveraged to overwrite the return address of the calling function, allowing an attacker to redirect execution flow to malicious code injected into the stack. The impact is particularly severe as it requires no authentication credentials and can be exploited remotely, making it a prime target for automated exploitation campaigns. The vulnerability affects devices running firmware versions prior to the specified patches, indicating that NETGEAR has been aware of the issue and released remediation updates for each affected model.
Operationally, this vulnerability presents a significant risk to network security as it enables complete compromise of affected routers without requiring any prior authentication. Once exploited, attackers can gain full administrative control over the device, potentially leading to man-in-the-middle attacks, DNS hijacking, traffic interception, and the ability to use the compromised device as a pivot point for attacking internal network resources. The widespread impact across multiple router series demonstrates that this is not an isolated incident but rather a systemic issue in how NETGEAR implemented input validation in their embedded web servers. From an ATT&CK framework perspective, this vulnerability maps to T1071.004 Application Layer Protocol: DNS and T1046 Network Service Scanning, as attackers can use the compromised device to conduct further reconnaissance and lateral movement within networks. The vulnerability also aligns with T1059 Command and Scripting Interpreter, as the attacker can execute arbitrary commands on the compromised device.
Mitigation strategies should prioritize immediate firmware updates from NETGEAR, as these patches address the root cause by implementing proper input validation and bounds checking mechanisms. Network administrators should also implement network segmentation to limit the potential impact of exploitation, disable unnecessary services such as remote administration, and monitor network traffic for suspicious patterns that may indicate exploitation attempts. Additional defensive measures include implementing intrusion detection systems with signatures for known exploitation patterns, configuring firewalls to restrict access to router management interfaces to trusted IP addresses only, and conducting regular vulnerability assessments of network infrastructure. Organizations should also consider implementing network access control measures to prevent unauthorized devices from connecting to the network and establish incident response procedures for rapid detection and remediation of potential compromises. The vulnerability serves as a reminder of the critical importance of maintaining up-to-date firmware in network infrastructure devices, particularly those with web-based management interfaces that are accessible from external networks.