CVE-2018-21188 in D7800
Summary
by MITRE
Certain NETGEAR devices are affected by a stack-based buffer overflow by an authenticated user. This affects D7800 before 1.0.1.30, R7500v2 before 1.0.3.24, R7800 before 1.0.2.40, R9000 before 1.0.2.52, WNDR3700v4 before 1.0.2.92, WNDR4300 before 1.0.2.94, WNDR4300v2 before 1.0.0.50, WNDR4500v3 before 1.0.0.50, and WNR2000v5 before 1.0.0.62.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 06/03/2024
This vulnerability represents a critical stack-based buffer overflow flaw affecting multiple NETGEAR router models that has significant implications for network security and device integrity. The issue arises from improper input validation within the web management interface of affected devices, allowing authenticated users to exploit a memory corruption vulnerability through crafted HTTP requests. The vulnerability specifically impacts devices running firmware versions prior to the listed patches, creating a widespread attack surface across various router models including the D7800, R7500v2, R7800, R9000, and several WNDR and WNR series devices. This type of vulnerability falls under CWE-121, which categorizes stack-based buffer overflow conditions as a fundamental memory safety issue. The authenticated nature of this vulnerability means that an attacker must first establish valid credentials to exploit the flaw, typically through legitimate administrative access or by compromising existing user accounts, which significantly reduces the attack surface but does not eliminate the risk entirely. The operational impact of this vulnerability extends beyond simple denial of service, as it could potentially allow for arbitrary code execution within the device's operating environment, providing attackers with persistent access to the network infrastructure. The buffer overflow occurs when the device processes user-supplied input through its web interface without adequate bounds checking, leading to memory corruption that can be leveraged to overwrite critical program data or execute malicious code. This vulnerability directly relates to ATT&CK technique T1059.007, which involves the use of command and scripting interpreter, as exploitation could enable attackers to execute commands on the affected devices. The affected firmware versions demonstrate a pattern of inadequate security testing and validation in the development lifecycle, particularly concerning input sanitization and memory management practices. Network administrators should be particularly concerned about this vulnerability because routers serve as critical network infrastructure components, and compromise of these devices can lead to complete network infiltration, data interception, and disruption of network services. The exploitation of this vulnerability can result in persistent backdoor access, allowing attackers to maintain long-term control over the affected network segment. The specific nature of the vulnerability means that any user with valid administrative credentials can potentially trigger the buffer overflow, making it particularly dangerous in environments where administrative access is shared or where credential compromise is possible.
The technical exploitation of this vulnerability requires understanding of the device's memory layout and the specific input fields that trigger the overflow condition. Attackers typically construct malicious HTTP requests that contain oversized input strings designed to overflow the stack buffer, potentially overwriting return addresses or other critical memory locations. The vulnerability's impact is amplified by the fact that these devices often operate in unsecured network environments where administrative interfaces may be accessible from external networks, particularly if default configurations are not properly changed. Security researchers have identified that the vulnerability stems from insufficient validation of user input within the device's web server component, which processes configuration requests from the management interface. This lack of input validation creates a direct pathway for attackers to manipulate memory contents, potentially leading to privilege escalation or complete device compromise. The vulnerability's classification as a stack-based buffer overflow aligns with common exploitation patterns found in embedded systems and network appliances, where memory management is critical due to limited resources and complex software architectures. Organizations should implement immediate mitigation strategies including firmware updates, network segmentation, and monitoring for unusual administrative access patterns. The vulnerability also highlights the importance of secure coding practices and proper input validation in embedded systems, particularly those handling network communications and user interfaces. Network security teams should prioritize patching these devices as a high-priority task, given their role as network gateways and the potential for widespread impact if exploited. The vulnerability's presence in multiple device models indicates a systemic issue in the development and testing processes of these networking devices, suggesting that similar vulnerabilities may exist in other components of the affected product lines. Regular security assessments and vulnerability scanning should be implemented to identify other potential weaknesses in network infrastructure devices, particularly those running legacy firmware versions that may contain unpatched security flaws.
The long-term implications of this vulnerability extend beyond immediate exploitation, as compromised devices can serve as persistent footholds within network environments. Attackers who successfully exploit this vulnerability can establish backdoors that provide continuous access to the network, potentially enabling data exfiltration, lateral movement, or further attacks on connected systems. The authenticated nature of the vulnerability means that once an attacker gains administrative credentials, they can leverage the buffer overflow to escalate privileges or execute arbitrary code with elevated system permissions. This vulnerability also demonstrates the critical importance of firmware security and the need for robust security testing in embedded networking equipment. The affected devices represent a significant portion of consumer and small office network infrastructure, making this vulnerability particularly concerning from a widespread impact perspective. Security professionals should consider implementing network monitoring solutions that can detect unusual patterns of administrative access or configuration changes that might indicate exploitation attempts. The vulnerability's existence in multiple device models suggests that manufacturers should improve their security testing protocols and implement more rigorous input validation measures in their development processes. Additionally, the vulnerability highlights the need for better firmware update mechanisms and more frequent security patches, particularly for devices that remain in production for extended periods without significant security improvements. Organizations should also consider implementing network access controls to limit access to administrative interfaces and ensure that only authorized personnel can access sensitive network management functions. The vulnerability's impact on network infrastructure security underscores the importance of maintaining up-to-date security practices across all network components, particularly those that serve as gateways between internal and external networks.