1. EXECUTIVE SUMMARY

CVSS v3 8.6
ATTENTION: Exploitable remotely/low attack complexity 
Vendor: Nexx
Equipment: Garage Door Controller, Smart Plug, Smart Alarm
Vulnerabilities: Use of Hard-coded Credentials, Authorization Bypass through User-controlled Key, Improper Input Validation, Improper Authentication

2. RISK EVALUATION

Successful exploitation of these vulnerabilities could allow an attacker to receive sensitive information, execute application programmable interface (API) requests, or hijack devices.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following versions of Nexx Smart Home devices are affected:

Nexx Garage Door Controller (NXG-100B, NXG-200): Version nxg200v-p3-4-1 and prior
Nexx Smart Plug (NXPG-100W): Version nxpg100cv4-0-0 and prior
Nexx Smart Alarm (NXAL-100): Version nxal100v-p1-9-1and prior

3.2 VULNERABILITY OVERVIEW

3.2.1    USE OF HARD-CODED CREDENTIALS CWE-798
The listed versions of Nexx Smart Home devices use hard-coded credentials. An attacker with unauthenticated access to the Nexx Home mobile application or the affected firmware could view the credentials and access the MQ Telemetry Server (MQTT) server and the ability to remotely control garage doors or smart plugs for any customer.

CVE-2023-1748 has been assigned to this vulnerability. A CVSS v3 base score of 8.6 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:L).

3.2.2    AUTHORIZATION BYPASS THROUGH USER-CONTROLLED KEY CWE-639
The listed versions of Nexx Smart Home devices lack proper access control when executing actions. An attacker with a valid NexxHome deviceId could send API requests that the affected devices would execute.

CVE-2023-1749 has been assigned to this vulnerability. A CVSS v3 base score of 6.5 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N).

3.2.3    AUTHORIZATION BYPASS THROUGH USER-CONTROLLED KEY CWE-639
The listed versions of Nexx Smart Home devices lack proper access control when executing actions. An attacker with a valid NexxHome deviceId could retrieve device history, set device settings, and retrieve device information. 

CVE-2023-1750 has been assigned to this vulnerability. A CVSS v3 base score of 7.1 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N).

3.2.4    IMPROPER INPUT VALIDATION CWE-20
The listed versions of Nexx Smart Home devices use a WebSocket server that does not validate if the bearer token in the Authorization header belongs to the device attempting to associate. This could allow any authorized user to receive alarm information and signals meant for other devices which leak a deviceId.

CVE-2023-1751 has been assigned to this vulnerability. A CVSS v3 base score of 7.5 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N).

3.2.5    IMPROPER AUTHENTICATION CWE-287
The listed versions of Nexx Smart Home devices could allow any user to register an already registered alarm or associated device with only the device’s MAC address.

CVE-2023-1752 has been assigned to this vulnerability. A CVSS v3 base score of 8.1 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H).

3.3 BACKGROUND

CRITICAL INFRASTRUCTURE SECTORS: Commercial Facilities
COUNTRIES/AREAS DEPLOYED: Worldwide 
COMPANY HEADQUARTERS LOCATION: United States

3.4 RESEARCHER

Sam Sabetan reported these vulnerabilities to CISA.

4. MITIGATIONS

Nexx has not responded to requests to work with CISA to mitigate these vulnerabilities. Users of the affected product are encouraged to contact Nexx support for additional information.

CISA recommends users take defensive measures to minimize the risk of exploitation of this vulnerability these vulnerabilities. Specifically, users should:

Minimize network exposure for all control system devices and/or systems, and ensure they are not accessible from the Internet.
Locate control system networks and remote devices behind firewalls and isolate them from business networks.
When remote access is required, use secure methods, such as Virtual Private Networks (VPNs), recognizing VPNs may have vulnerabilities and should be updated to the most current version available. Also recognize VPN is only as secure as its connected devices.

CISA reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures.

CISA also provides a section for control systems security recommended practices on the ICS webpage at cisa.gov/ics. Several CISA products detailing cyber defense best practices are available for reading and download, including Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies.

Additional mitigation guidance and recommended practices are publicly available on the ICS webpage at cisa.gov/ics in the technical information paper, ICS-TIP-12-146-01B–Targeted Cyber Intrusion Detection and Mitigation Strategies.

Organizations observing suspected malicious activity should follow established internal procedures and report findings to CISA for tracking and correlation against other incidents.

No known public exploits specifically target these vulnerabilities.