CVE-2023-48121: Ezviz Camera Authentication Bypass Flaw

CVE-2023-48121 Overview

CVE-2023-48121 is an authentication bypass vulnerability affecting the Direct Connection Module in multiple Ezviz smart camera product lines. This vulnerability allows remote attackers to bypass authentication mechanisms and obtain sensitive information by sending specially crafted messages to affected devices. The flaw exists in firmware versions prior to v5.3.x build 20230401 across several Ezviz camera models, potentially exposing thousands of IoT devices to unauthorized access.

Critical Impact

Remote attackers can bypass authentication in Ezviz smart cameras to access sensitive device information without credentials, compromising surveillance infrastructure and user privacy.

Affected Products

• Ezviz CS-C6N-xxx (firmware prior to v5.3.x build 20230401)
• Ezviz CS-CV310-xxx (firmware prior to v5.3.x build 20230401)
• Ezviz CS-C6CN-xxx (firmware prior to v5.3.x build 20230401)
• Ezviz CS-C3N-xxx (firmware prior to v5.3.x build 20230401)

Discovery Timeline

• 2023-11-28 - CVE-2023-48121 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-48121

Vulnerability Analysis

This authentication bypass vulnerability (CWE-287) resides in the Direct Connection Module of affected Ezviz camera firmware. The vulnerability enables remote attackers to circumvent normal authentication procedures when communicating with the device's network interface. By exploiting this flaw, attackers can access sensitive information that should be protected behind authentication controls.

The Direct Connection Module is designed to facilitate peer-to-peer connections between Ezviz cameras and client applications. However, improper authentication validation in this module allows malicious actors to interact with the device without presenting valid credentials. This weakness is particularly concerning for IoT surveillance devices, as it may expose video feeds, device configurations, network credentials, and other sensitive data stored on or accessible through the camera.

Root Cause

The root cause of this vulnerability is improper authentication validation (CWE-287) within the Direct Connection Module. The firmware fails to properly verify authentication credentials when processing certain message types, allowing unauthenticated requests to be processed as if they were legitimate authenticated sessions. This implementation flaw enables attackers to bypass security controls entirely by crafting messages that exploit the authentication validation logic.

Attack Vector

The attack vector is network-based, requiring no user interaction or prior authentication. An attacker with network access to an affected Ezviz camera can exploit this vulnerability by:

1. Identifying a vulnerable Ezviz camera on the network through device discovery or scanning
2. Crafting malicious messages targeting the Direct Connection Module
3. Sending these messages to the camera's network interface
4. Receiving sensitive information in response without providing valid credentials

The attack can be conducted remotely over the network, making any internet-exposed or locally accessible Ezviz camera a potential target. For technical details on the vulnerability mechanism, refer to the GitHub Vulnerability Report published by the security researcher.

Detection Methods for CVE-2023-48121

Indicators of Compromise

• Unexpected network connections to Ezviz cameras from unknown IP addresses
• Anomalous traffic patterns to the Direct Connection Module ports
• Authentication logs showing access without corresponding login events
• Unusual data exfiltration from camera devices

Detection Strategies

• Monitor network traffic to Ezviz cameras for malformed or suspicious message patterns
• Implement network segmentation to isolate IoT cameras and detect lateral movement attempts
• Deploy intrusion detection systems (IDS) with rules targeting authentication bypass attempts on IoT devices
• Review camera access logs for requests that bypass normal authentication flows

Monitoring Recommendations

• Enable comprehensive logging on network devices interfacing with Ezviz cameras
• Set up alerts for connections to cameras from unauthorized network segments
• Monitor for firmware version mismatches indicating unpatched devices
• Implement network traffic analysis for IoT device segments to detect anomalous communication patterns

How to Mitigate CVE-2023-48121

Immediate Actions Required

• Update all affected Ezviz cameras to firmware version v5.3.x build 20230401 or later immediately
• Audit your network for all Ezviz camera models listed in the affected products
• Isolate cameras that cannot be immediately updated on a separate network segment
• Review access logs for signs of exploitation prior to patching

Patch Information

Ezviz has released patched firmware versions to address this vulnerability. The fixed firmware is v5.3.x build 20230401 or later for all affected product lines. Administrators should download the latest firmware from the official EZVIZ Security Notice page and apply updates to all vulnerable devices. For related Hikvision products, consult the Hikvision Security Advisory for additional guidance.

Workarounds

• Place vulnerable cameras behind a firewall with strict access controls limiting connectivity to trusted IP addresses only
• Disable the Direct Connection feature if not required for your deployment
• Implement VPN requirements for remote access to camera systems
• Use network access control lists (ACLs) to restrict which devices can communicate with cameras

# Example firewall rule to restrict camera access (iptables)
# Replace 192.168.1.100 with your camera IP and 10.0.0.0/24 with trusted network
iptables -A INPUT -d 192.168.1.100 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -d 192.168.1.100 -j DROP