CVE-2019-20735 in D3600
Summary
by MITRE
Certain NETGEAR devices are affected by a stack-based buffer overflow by an authenticated user. This affects D3600 before 1.0.0.75, D6000 before V1.0.0.75, D6100 before V1.0.0.63, R7800 before v1.0.2.52, R8900 before v1.0.4.2, R9000 before v1.0.4.2, RBK50 before v2.3.0.32, RBR50 before v2.3.0.32, RBS50 before v2.3.0.32, WNDR3700v4 before V1.0.2.102, WNDR4300v1 before V1.0.2.104, WNDR4300v2 before v1.0.0.58, WNDR4500v3 before v1.0.0.58, WNR2000v5 before v1.0.0.68, and XR500 before V2.3.2.32.
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Analysis
by VulDB Data Team • 05/31/2024
This vulnerability represents a critical stack-based buffer overflow flaw affecting multiple NETGEAR networking devices within their consumer and small business product lines. The issue stems from improper input validation within the device's web interface handling mechanism, specifically when processing user-supplied data through authenticated administrative sessions. The vulnerability exists in firmware versions prior to the specified patches, indicating a widespread exposure across various router models including the R7800, R8900, and numerous wireless N and AC series devices. The stack-based nature of the overflow means that malicious input can overwrite adjacent memory locations on the program stack, potentially leading to arbitrary code execution or system crashes.
The technical exploitation of this vulnerability requires an authenticated user with administrative privileges, which significantly reduces the attack surface compared to unauthenticated exploits. However, the impact remains severe as authenticated attackers can leverage this flaw to execute arbitrary code on the affected devices. The vulnerability maps directly to CWE-121 Stack-based Buffer Overflow, which is classified as a high-severity weakness in the Common Weakness Enumeration catalog. This weakness specifically addresses buffer overflows occurring in stack memory regions where insufficient bounds checking allows attackers to overwrite stack contents and potentially redirect program execution flow.
From an operational perspective, the implications extend beyond simple device compromise to potentially enable broader network infiltration and persistent access. Attackers who gain administrative control of these devices can manipulate network routing, redirect traffic through malicious intermediaries, or establish backdoors for continued access. The affected devices typically serve as primary network gateways for residential and small business environments, making them attractive targets for attackers seeking to establish footholds within larger networks. This vulnerability aligns with ATT&CK technique T1059.007 Command and Scripting Interpreter: PowerShell, as the exploitation may involve crafting malicious payloads that leverage the buffer overflow to execute arbitrary commands on the compromised device.
The mitigation strategy for this vulnerability involves immediate firmware updates from NETGEAR, as the vendor has released patches addressing the specific buffer overflow conditions. Network administrators should prioritize updating all affected devices in their inventory, particularly those with exposed administrative interfaces. Additional defensive measures include implementing network segmentation to limit access to administrative interfaces, enforcing strong authentication controls, and monitoring for unusual administrative activities that might indicate exploitation attempts. The vulnerability also highlights the importance of regular firmware updates and security assessments for network infrastructure devices, as these devices often remain unpatched for extended periods. Organizations should also consider implementing network access controls that restrict administrative access to these devices to only trusted administrative workstations, thereby reducing the attack surface for authenticated exploits.