CVE-2018-21183 in R7800
Summary
by MITRE
Certain NETGEAR devices are affected by a stack-based buffer overflow by an authenticated user. This affects R7800 before 1.0.2.40, R9000 before 1.0.2.52, WNDR3700v4 before 1.0.2.92, and WNDR4300 before 1.0.2.94.
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Analysis
by VulDB Data Team • 06/03/2024
This vulnerability represents a critical stack-based buffer overflow flaw in NETGEAR router firmware that enables authenticated users to execute arbitrary code remotely. The vulnerability affects multiple models including the R7800, R9000, WNDR3700v4, and WNDR4300 routers, with specific firmware versions identified as vulnerable. The issue stems from improper input validation within the device's web interface handling routines, where user-supplied data is copied to insufficiently sized stack buffers without proper bounds checking. This fundamental flaw allows an attacker who has already gained administrative credentials to exploit the buffer overflow condition and potentially gain complete control over the affected devices.
The technical implementation of this vulnerability involves a classic stack buffer overflow scenario where malicious input is passed through the web management interface to a vulnerable function. When an authenticated user submits crafted data to specific parameters within the router's administration panel, the system fails to validate the input length against the allocated buffer space. This results in memory corruption that can be leveraged to overwrite adjacent stack variables, function return addresses, or other critical memory locations. The vulnerability is particularly dangerous because it requires only authenticated access, meaning that an attacker who has already compromised administrative credentials or gained access through other means can exploit this flaw to escalate their privileges or execute arbitrary code on the affected devices.
From an operational impact perspective, this vulnerability poses significant risks to network security infrastructure as it allows for complete device compromise. Once exploited, the attacker can gain root access to the router's operating system, potentially enabling them to modify network configurations, redirect traffic, establish backdoors, or use the compromised device as a pivot point for attacking other systems within the network. The vulnerability's presence in multiple router models across different firmware versions indicates a widespread issue that affects various network environments, from home users to enterprise deployments. Organizations relying on these devices for network security functions face particular concern as the compromise of these routers could undermine their entire network security posture.
The vulnerability aligns with CWE-121 Stack-based Buffer Overflow, which specifically addresses buffer overflows occurring in stack memory regions where insufficient bounds checking allows data to overwrite adjacent memory locations. This flaw also maps to several ATT&CK techniques including T1059 Command and Scripting Interpreter and T1068 Exploitation for Privilege Escalation, as the vulnerability enables an attacker to execute commands with elevated privileges. Network administrators should prioritize immediate firmware updates for all affected devices, as the patching process typically involves correcting input validation routines and ensuring proper buffer size management. Additionally, organizations should implement network monitoring to detect unusual traffic patterns that might indicate exploitation attempts, and consider network segmentation to limit the potential impact of successful compromises. The vulnerability demonstrates the critical importance of proper input validation and memory management practices in embedded systems, particularly those handling network administration interfaces where authenticated access is required.