CVE-2021-34829 in DAP-1330
Summary
by MITRE • 07/16/2021
This vulnerability allows network-adjacent attackers to execute arbitrary code on affected installations of D-Link DAP-1330 1.13B01 BETA routers. Authentication is not required to exploit this vulnerability. The specific flaw exists within the handling of the HNAP_AUTH HTTP header. The issue results from the lack of proper validation of the length of user-supplied data prior to copying it to a fixed-length buffer. An attacker can leverage this vulnerability to execute code in the context of the device. Was ZDI-CAN-12065.
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Analysis
by VulDB Data Team • 07/19/2021
The vulnerability identified as CVE-2021-34829 represents a critical buffer overflow flaw in D-Link DAP-1330 1.13B01 BETA routers that exposes devices to remote code execution without requiring authentication. This vulnerability falls under CWE-121, which describes stack-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations. The flaw specifically manifests in the HTTP header processing mechanism, particularly within the HNAP_AUTH header handling, making it accessible to network-adjacent attackers who can exploit the vulnerability from the same local network segment.
The technical implementation of this vulnerability stems from improper input validation during the processing of HTTP headers in the router's web interface. When the device receives an HNAP_AUTH header, it fails to properly validate the length of the supplied data before copying it into a fixed-length buffer allocated in memory. This classic buffer overflow condition allows attackers to craft malicious HTTP requests with excessively long HNAP_AUTH header values that exceed the buffer capacity. The overflow can overwrite adjacent memory locations including return addresses, function pointers, or other critical control data, enabling arbitrary code execution with the privileges of the affected service.
From an operational perspective, this vulnerability presents a severe risk to network security as it eliminates the need for authentication, making exploitation accessible to any attacker within the local network segment. The D-Link DAP-1330 router serves as a wireless access point and network gateway, making it a prime target for attackers seeking to establish persistent access to network infrastructure. Once successfully exploited, the attacker gains full control over the router's operating system, potentially enabling them to modify network configurations, redirect traffic, install malware, or use the device as a pivot point for attacking other systems within the network. This aligns with ATT&CK technique T1059, which covers command and script injection, and T1071, covering application layer protocol usage.
The exploitation of this vulnerability can be achieved through various attack vectors within the local network environment, including but not limited to man-in-the-middle attacks, compromised devices, or social engineering campaigns targeting network administrators. The lack of authentication requirements makes this vulnerability particularly dangerous as it can be exploited by attackers who have only network access, without requiring valid credentials or physical access to the device. Security professionals should consider this vulnerability in their risk assessments for enterprise networks, particularly those with unsecured wireless access points or insufficient network segmentation controls.
Mitigation strategies for this vulnerability should include immediate firmware updates from D-Link to address the buffer overflow condition, network segmentation to isolate critical devices, and implementation of intrusion detection systems to monitor for suspicious HTTP header patterns. Organizations should also consider disabling unnecessary services and ports on affected devices, implementing network access control lists to restrict access to the router's web interface, and conducting regular vulnerability assessments to identify similar issues in other network infrastructure components. The vulnerability demonstrates the critical importance of proper input validation and bounds checking in embedded systems, particularly those handling network communications where untrusted data sources are common.