CVE-2022-40903 is a vulnerability identified in the Aiphone GT-DMB-N 3-in-1 Video Entrance Station with NFC Reader, version 1.0.3. This device integrates video intercom functionality with NFC-based access control, commonly used in building security systems to manage and monitor entry points. The vulnerability arises from the device's failure to implement adequate protections against repeated failed access attempts. Specifically, it does not enforce throttling, lockouts, or other mitigations to prevent brute force or repeated guessing attacks on authentication mechanisms. As a result, an attacker can repeatedly attempt to authenticate without restriction, eventually gaining administrative privileges on the device. This elevation of privilege allows the attacker to potentially control the device’s configuration, access logs, and connected systems. The CVSS 3.1 base score is 6.5 (medium severity), with an attack vector classified as adjacent network (AV:A), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), unchanged scope (S:U), high confidentiality impact (C:H), no integrity impact (I:N), and no availability impact (A:N). The vulnerability is categorized under CWE-307, which relates to improper restriction of excessive authentication attempts. No patches or known exploits in the wild have been reported as of the publication date (November 14, 2022). This vulnerability highlights a significant security gap in access control mechanisms of physical security devices that could be exploited to compromise building entry systems and associated infrastructure.

For European organizations, this vulnerability poses a notable risk to physical security and potentially to broader network security. The Aiphone GT-DMB-N device is used in commercial, residential, and institutional buildings to control access points. Successful exploitation could allow unauthorized administrative access, enabling attackers to manipulate entry permissions, disable security monitoring, or gain insights into building occupancy and security configurations. This could facilitate unauthorized physical access, espionage, or sabotage. Given the high confidentiality impact, sensitive information such as access logs or user credentials could be exposed. Although the vulnerability does not directly impact system integrity or availability, the administrative control gained could be leveraged to perform further malicious actions. Organizations in sectors with high security requirements—such as government facilities, critical infrastructure, healthcare, and finance—are particularly at risk. The lack of user interaction and no need for prior privileges make exploitation feasible for attackers with network adjacency, such as those physically near the device or connected to the same local network segment. This elevates the threat in environments where physical security devices are accessible to multiple parties or where network segmentation is insufficient.

To mitigate this vulnerability, European organizations should implement the following specific measures: 1) Network Segmentation: Isolate the Aiphone GT-DMB-N devices on dedicated VLANs or subnets with strict access controls to limit exposure to only authorized management stations and reduce the attack surface. 2) Physical Security: Restrict physical access to the devices and their network connections to prevent attackers from gaining network adjacency. 3) Monitoring and Alerting: Deploy intrusion detection systems (IDS) or network monitoring tools to detect repeated failed authentication attempts against these devices and generate alerts for security teams. 4) Firmware Updates: Although no patches are currently available, maintain close communication with the vendor for firmware updates or security advisories addressing this issue and apply them promptly once released. 5) Access Control Policies: Implement strong authentication mechanisms on management interfaces, including multi-factor authentication if supported, and change default credentials. 6) Rate Limiting Proxies: Where possible, deploy network-level rate limiting or proxy solutions that can throttle repeated authentication attempts to the device. 7) Incident Response Planning: Prepare response procedures for potential compromise scenarios involving physical security devices to minimize impact and restore secure configurations quickly. These targeted controls go beyond generic advice by focusing on network architecture, monitoring, and physical security integration specific to the affected device type.