CVE-2018-21174 in D6100
Summary
by MITRE
Certain NETGEAR devices are affected by a stack-based buffer overflow by an authenticated user. This affects D6100 before 1.0.0.57, R7500 before 1.0.0.122, 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.
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Analysis
by VulDB Data Team • 06/03/2024
This vulnerability represents a critical stack-based buffer overflow flaw that affects multiple NETGEAR router models, creating a significant security risk for network infrastructure. The vulnerability is classified as a stack-based buffer overflow under CWE-121, which occurs when a program writes data beyond the bounds of a fixed-length buffer allocated on the stack. This specific flaw is exploitable by authenticated users, meaning that an attacker must first establish valid credentials to access the device's management interface before they can leverage this vulnerability. The affected devices span several popular NETGEAR router series including the D6100, R7500, R7800, R9000, and various WNDR models, indicating a widespread issue that impacts a substantial portion of NETGEAR's consumer and small business product lineup. The vulnerability exists in firmware versions prior to the specified patches, with each model having its own version threshold for the affected state.
The technical exploitation of this buffer overflow occurs within the device's web management interface, where authenticated users can submit malicious input to specific parameters that trigger the overflow condition. When the vulnerable application processes user-supplied input without proper bounds checking, it writes data beyond the allocated stack buffer space, potentially overwriting adjacent memory locations including return addresses and control data. This memory corruption can lead to arbitrary code execution or system crashes, depending on how the overflow affects the program's execution flow. The vulnerability's classification under the ATT&CK framework falls under T1210 - Exploitation of Remote Services, as it represents an authenticated exploitation vector that allows for privilege escalation and potential system compromise. Attackers could leverage this vulnerability to gain unauthorized access to the device's administrative functions, potentially enabling them to modify network configurations, install malicious firmware, or redirect network traffic through the compromised router.
The operational impact of this vulnerability extends beyond simple device compromise, as compromised routers can serve as persistent footholds for broader network attacks. Network administrators face significant risks when these devices remain unpatched, as they become potential entry points for attackers seeking to establish persistent access to corporate networks or home networks with elevated privileges. The vulnerability's authenticated nature means that attackers typically need to obtain valid user credentials through phishing, credential reuse, or other social engineering techniques before exploiting the buffer overflow. This makes the attack surface more manageable for defenders but still represents a serious threat, especially in environments where device management credentials are weak or reused across multiple systems. The affected firmware versions indicate that this vulnerability has been present for an extended period, potentially allowing attackers to develop and deploy exploits before vendors released patches, creating a window of opportunity for active exploitation in the wild.
Mitigation strategies for this vulnerability require immediate firmware updates from NETGEAR to address the buffer overflow condition through proper input validation and bounds checking mechanisms. Network administrators should prioritize patching all affected devices, particularly those with public internet exposure or those serving critical network functions. The recommended approach includes verifying the current firmware version against the vendor's published patch list, downloading the appropriate firmware update from NETGEAR's official support channels, and following the manufacturer's documented update procedures to avoid potential device bricking during the update process. Additional defensive measures include implementing network segmentation to limit access to administrative interfaces, enforcing strong authentication practices with multi-factor authentication where possible, and monitoring network traffic for unusual patterns that might indicate exploitation attempts. Organizations should also consider implementing network access controls to restrict administrative access to only trusted IP addresses and establish baseline configurations that minimize the attack surface of these devices. Security teams should monitor vulnerability databases and vendor advisories for similar issues that might affect other network equipment in their environment, as this vulnerability demonstrates the importance of maintaining up-to-date firmware across all network infrastructure components. The vulnerability serves as a reminder of the critical importance of firmware security and the need for regular security assessments of network devices that are often overlooked in traditional security monitoring programs.