CVE-2018-21156 in D6220
Summary
by MITRE
Certain NETGEAR devices are affected by a buffer overflow by an authenticated user. This affects D6220 before 1.0.0.38, D6400 before 1.0.0.74, D7000v2 before 1.0.0.74, D8500 before 1.0.3.39, DGN2200v4 before 1.0.0.102, DGN2200Bv4 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, R6250 before 1.0.4.20, R6300v2 before 1.0.4.22, R6400 before 1.0.1.32, R6400v2 before 1.0.2.52, R6700 before 1.0.1.44, R6900 before 1.0.1.44, R6900P before 1.3.0.18, R7000 before 1.0.9.28, R7000P before 1.3.0.18, R7300DST before 1.0.0.62, R7900 before 1.0.2.10, R7900P before 1.3.0.10, R8000 before 1.0.4.12, R8000P before 1.3.0.10, R8300 before 1.0.2.116, R8500 before 1.0.2.116, WN2500RPv2 before 1.0.1.52, WNDR3400v3 before 1.0.1.18, and WNR3500Lv2 before 1.2.0.46.
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Analysis
by VulDB Data Team • 06/03/2024
This vulnerability represents a critical buffer overflow condition that affects multiple NETGEAR router models, specifically identified as CVE-2018-21156. The flaw manifests within the web-based management interface of affected devices, where an authenticated user can exploit a memory corruption issue through crafted input parameters. The vulnerability stems from improper bounds checking in the processing of user-supplied data, creating an opportunity for attackers to execute arbitrary code or cause system crashes. This type of vulnerability is categorized under CWE-121 as a stack-based buffer overflow, which occurs when more data is written to a fixed-length buffer than it can accommodate, leading to memory corruption. The affected devices span across various router series including D-series, EX-series, R-series, and WNR-series, indicating a widespread issue within NETGEAR's product portfolio. The vulnerability is particularly concerning because it requires only authenticated access, meaning an attacker who has already gained administrative credentials or can obtain them through other means can leverage this flaw to escalate privileges or disrupt service availability.
The technical exploitation of this buffer overflow occurs during the processing of HTTP requests sent to the device's web interface, where user-controllable parameters are not properly validated before being copied into insufficiently sized memory buffers. When an authenticated user sends malicious input through the web management interface, the system fails to check the length of the input against the allocated buffer space, allowing the overflow to occur. This memory corruption can potentially overwrite adjacent memory locations, including return addresses and function pointers, enabling attackers to redirect program execution flow. The impact extends beyond simple denial of service, as successful exploitation could allow an attacker to execute arbitrary code with the privileges of the web server process, which typically runs with administrative rights on the device. This aligns with ATT&CK technique T1059.007 for command and script interpreter execution, where an attacker could leverage this vulnerability to establish persistent access or deploy additional malicious payloads. The vulnerability affects firmware versions prior to specific release numbers, indicating that NETGEAR has acknowledged and patched this issue in later releases, though the widespread nature of affected models suggests many devices may remain unpatched in production environments.
The operational implications of this vulnerability are severe for network infrastructure security, as routers serve as critical gateways for network communications and often contain sensitive configuration data. An attacker who successfully exploits this vulnerability could gain complete control over the affected router, potentially leading to man-in-the-middle attacks, network traffic interception, or complete network compromise. The authenticated nature of the attack means that even if an attacker cannot directly access the device, they may still be able to compromise it through social engineering, credential theft, or other means to obtain administrative access. This vulnerability particularly affects enterprise and home network environments where these devices are commonly deployed, creating potential attack vectors for lateral movement within networks or for establishing persistent backdoors. Organizations should consider the broader implications of such vulnerabilities, as compromised routers can serve as stepping stones for more extensive network breaches. The vulnerability also highlights the importance of firmware update management, as many affected devices may continue operating with vulnerable firmware for extended periods due to lack of automated updates or user awareness. Network defenders should implement monitoring for unusual traffic patterns or access attempts to these devices, as exploitation attempts may generate detectable anomalies in network logs or device behavior. The presence of this vulnerability in multiple router models suggests a systemic issue in the development or testing processes, indicating that similar flaws may exist in other components of the affected firmware. This vulnerability underscores the necessity for regular security assessments of network infrastructure components and the importance of maintaining up-to-date firmware across all network devices. The remediation process requires immediate firmware updates from NETGEAR for all affected models, with network administrators prioritizing deployment of patches across their entire device inventory. The vulnerability also demonstrates the importance of secure coding practices and input validation, particularly for web-based management interfaces that handle user-provided data. Organizations should consider implementing network segmentation and access controls to limit the potential impact of such vulnerabilities, while also establishing procedures for rapid response to security advisories and vulnerability notifications from vendors.