CVE-2021-45609 in D8500
Summary
by MITRE • 12/26/2021
Certain NETGEAR devices are affected by a buffer overflow by an unauthenticated attacker. This affects D8500 before 1.0.3.58, R6250 before 1.0.4.48, R7000 before 1.0.11.116, R7100LG before 1.0.0.64, R7900 before 1.0.4.38, R8300 before 1.0.2.144, R8500 before 1.0.2.144, XR300 before 1.0.3.68, R7000P before 1.3.2.132, and R6900P before 1.3.2.132.
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Analysis
by VulDB Data Team • 12/28/2021
The vulnerability identified as CVE-2021-45609 represents a critical buffer overflow flaw affecting multiple NETGEAR router models, specifically targeting devices in the D8500, R6250, R7000, R7100LG, R7900, R8300, R8500, XR300, R7000P, and R6900P families. This vulnerability exists within the web-based management interface of these devices, creating a significant security risk that can be exploited by unauthenticated attackers without requiring any credentials or prior access to the network. The affected firmware versions indicate that this flaw has been present across multiple generations of NETGEAR routers, suggesting a widespread impact that spans several years of product releases.
The technical nature of this buffer overflow vulnerability stems from improper input validation within the device's web server implementation. When processing HTTP requests through the web interface, the system fails to properly check the length of incoming data before copying it into fixed-size buffers, allowing an attacker to overflow these buffers and potentially overwrite adjacent memory locations. This type of vulnerability falls under CWE-121, which specifically addresses stack-based buffer overflow conditions, and represents a classic example of unsafe memory manipulation practices that have been documented in cybersecurity literature for decades. The vulnerability's classification as unauthenticated means that an attacker can exploit it from outside the network, making it particularly dangerous for home and small office networks where routers are often directly exposed to internet traffic.
The operational impact of this vulnerability extends beyond simple remote code execution capabilities, as it creates potential for complete device compromise and network infiltration. An attacker who successfully exploits this buffer overflow could gain unauthorized access to the router's administrative functions, potentially allowing for configuration changes, network traffic interception, or even the installation of persistent backdoors. The vulnerability's presence in multiple router models indicates that a single attack vector could affect numerous devices simultaneously, making it an attractive target for automated exploitation campaigns. This type of vulnerability aligns with ATT&CK technique T1071.004, which describes application layer protocol usage for command and control communications, as compromised routers could be used as pivot points for further network reconnaissance and lateral movement.
Mitigation strategies for CVE-2021-45609 should prioritize immediate firmware updates from NETGEAR, as the vendor has released patches addressing this specific vulnerability in versions beyond the affected firmware releases. Network administrators should implement network segmentation to limit the potential impact of a compromised device and consider disabling remote management features where possible. The vulnerability's nature as a buffer overflow makes it particularly susceptible to exploitation through malformed HTTP requests, which can be detected and blocked through proper network monitoring and intrusion detection systems. Organizations should also implement regular vulnerability scanning procedures to identify potentially affected devices on their networks and ensure that all network equipment receives timely security updates. Additionally, the use of network access control lists and firewall rules to restrict access to router management interfaces from untrusted networks provides an additional layer of defense against this type of exploitation.