CVE-2019-20762 in D8500
Summary
by MITRE
Certain NETGEAR devices are affected by a buffer overflow by an authenticated user. This affects D8500 before 1.0.3.43, R8500 before 1.0.2.128, R8300 before 1.0.2.128, R8000 before 1.0.4.28, R7300DST before 1.0.0.68, R7100LG before 1.0.0.48, R6900P before 1.3.1.44, R7900P before 1.4.1.30, R8000P before 1.4.1.30, R7000P before 1.3.1.44, R7000 before 1.0.9.34, R6900 before 1.0.2.4, R6700 before 1.0.2.6, and R6400 before 1.0.1.44.
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Analysis
by VulDB Data Team • 05/31/2024
The vulnerability identified as CVE-2019-20762 represents a critical buffer overflow flaw affecting multiple NETGEAR router models within their consumer and small business product lines. This issue arises from insufficient input validation in the web interface of affected devices, specifically when processing user-supplied data through HTTP request parameters. The flaw allows authenticated attackers who have already gained access to the device's administrative interface to exploit memory corruption vulnerabilities that could lead to arbitrary code execution or system crashes. The affected models span several generations of NETGEAR routers including the D8500, R8500, R8300, R8000, R7300DST, R7100LG, R6900P, R7900P, R8000P, R7000P, R7000, R6900, R6700, and R6400 series, with specific firmware version thresholds indicating the scope of impacted devices.
This vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations. The attack vector requires an authenticated user, meaning that an adversary must first obtain valid credentials to access the router's web management interface. However, the security implications remain severe since routers serve as primary network gateways and often possess elevated privileges within local networks. The buffer overflow occurs when the device processes user input without proper validation, potentially allowing malicious data to overwrite critical memory segments including return addresses, function pointers, or other control structures necessary for normal program execution.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially enable complete system compromise. An authenticated attacker could leverage this flaw to execute arbitrary code with the privileges of the web server process, which typically runs with administrative rights on the router. This could result in persistent backdoor access, network traffic interception, DNS hijacking, or the ability to modify router configurations without detection. The vulnerability affects devices that are widely deployed in residential and small office environments, where network security is often insufficiently managed, making these systems particularly attractive targets for exploitation. Network reconnaissance activities by threat actors could easily identify these vulnerable devices through banner identification or network scanning techniques, as many of these routers are accessible from external networks.
Mitigation strategies for CVE-2019-20762 primarily focus on firmware updates provided by NETGEAR, which address the underlying buffer overflow conditions through proper input validation and memory management practices. Organizations and individuals should immediately apply the vendor-supplied patches to all affected devices, particularly noting that firmware versions 1.0.3.43, 1.0.2.128, 1.0.4.28, 1.0.0.68, 1.0.0.48, 1.3.1.44, 1.4.1.30, 1.3.1.44, 1.0.9.34, 1.0.2.4, 1.0.2.6, and 1.0.1.44 represent the minimum versions that should be deployed to remediate this vulnerability. Additional defensive measures include implementing network segmentation to isolate critical devices, disabling remote management features when possible, enforcing strong authentication mechanisms, and monitoring network traffic for suspicious activity that might indicate exploitation attempts. The vulnerability also aligns with ATT&CK technique T1072, which covers software deployment methods, as exploitation could enable attackers to install persistent backdoors or additional malicious software on affected networks. Regular network monitoring and vulnerability assessment activities should include identification of these specific router models to ensure comprehensive protection against similar future exploits.