CVE-2025-7503 Overview
CVE-2025-7503 is a critical hardcoded credentials vulnerability affecting OEM IP cameras manufactured by Shenzhen Liandian Communication Technology LTD. The device exposes a Telnet service on port 23 with undocumented default credentials, allowing unauthenticated attackers with network access to gain root-level shell access to the affected devices. This represents a severe security flaw in IoT device firmware that enables remote code execution and complete device compromise.
Critical Impact
Attackers can remotely authenticate to exposed IP cameras using default credentials and obtain full root access, enabling surveillance hijacking, network pivoting, and integration into botnets.
Affected Products
- Shenzhen Liandian Communication Technology OEM IP Camera
- Firmware version: AppFHE1_V1.0.6.0
- Kernel: KerFHE1_PTZ_WIFI_V3.1.1 (Hardware: HwFHE1_WF6_PTZ_WIFI_20201218)
Discovery Timeline
- July 11, 2025 - CVE-2025-7503 published to NVD
- July 15, 2025 - Last updated in NVD database
Technical Details for CVE-2025-7503
Vulnerability Analysis
This vulnerability stems from CWE-798 (Use of Hard-Coded Credentials), a critical flaw common in IoT and embedded devices. The affected IP camera ships with a Telnet service enabled by default on port 23, which is neither disclosed in the user manual nor configurable through the device's web interface. The Telnet service accepts authentication using undocumented default credentials that are identical across all devices running the vulnerable firmware.
The combination of an exposed network service with hardcoded credentials creates a trivially exploitable attack surface. Once authenticated, attackers receive root-level shell access, providing complete control over the device's operating system and functionality. This can be leveraged for surveillance interception, lateral movement within the network, or enrolling the device into IoT botnets.
No official fix or firmware update is available from the vendor. Attempts to contact Shenzhen Liandian Communication Technology LTD were unsuccessful, leaving affected devices permanently vulnerable unless removed from networks or protected by external security controls.
Root Cause
The root cause is the use of hardcoded credentials embedded in the device firmware for the Telnet service. This security anti-pattern violates fundamental secure development principles by:
- Shipping devices with default credentials that cannot be changed by end users
- Enabling a remote access service (Telnet) without user knowledge or consent
- Using the insecure Telnet protocol instead of encrypted alternatives like SSH
- Failing to document the service's existence, preventing users from taking protective measures
Attack Vector
The attack vector is network-based and requires no user interaction or prior authentication. An attacker with network visibility to the camera's port 23 can exploit this vulnerability through the following steps:
- Scan the network for devices with open Telnet services on port 23
- Identify vulnerable cameras through banner grabbing or fingerprinting
- Authenticate using the default credentials
- Execute arbitrary commands with root privileges
The attack is fully unauthenticated from the victim's perspective since the credentials are undocumented and not controlled by the device owner. Devices exposed directly to the internet are particularly at risk, as they can be discovered and exploited through mass scanning campaigns.
For technical details and research findings, see the GitHub Research Repository.
Detection Methods for CVE-2025-7503
Indicators of Compromise
- Unexpected Telnet connections to IP cameras on port 23
- Unusual outbound network traffic from camera devices indicating potential botnet enrollment
- New user accounts or modified system files on camera firmware
- Changes to camera configuration not initiated by administrators
Detection Strategies
- Perform network scanning to identify devices with open Telnet services on port 23
- Implement network flow analysis to detect Telnet authentication attempts to IoT devices
- Deploy honeypots mimicking vulnerable camera configurations to detect exploitation attempts
- Monitor for firmware version AppFHE1_V1.0.6.0 in device inventory management systems
Monitoring Recommendations
- Enable logging on network firewalls to capture all Telnet traffic destined for IoT device segments
- Implement intrusion detection rules to alert on Telnet connections to camera subnets
- Establish baseline network behavior for IP cameras and alert on anomalies
- Conduct periodic vulnerability assessments of IoT infrastructure
How to Mitigate CVE-2025-7503
Immediate Actions Required
- Isolate affected IP cameras on dedicated network segments with restricted access
- Block inbound connections to port 23 (Telnet) at the network perimeter and internal firewalls
- Disable or remove affected devices from production networks if feasible
- Audit network infrastructure for additional exposed IoT devices with similar vulnerabilities
Patch Information
No official patch or firmware update is available from the vendor. Shenzhen Liandian Communication Technology LTD could not be contacted regarding this vulnerability. Organizations using affected devices should implement compensating controls or consider device replacement with products from vendors with established security practices.
Workarounds
- Implement network segmentation to isolate IP cameras from critical infrastructure
- Deploy firewall rules blocking all traffic to port 23 on camera devices
- Use a VPN or secure gateway for remote camera access instead of direct exposure
- Consider replacing affected devices with cameras from vendors that provide security updates
# Firewall rule example to block Telnet access to camera subnet
# iptables rule to drop all Telnet traffic to camera network segment
iptables -A FORWARD -d 192.168.100.0/24 -p tcp --dport 23 -j DROP
iptables -A INPUT -d 192.168.100.0/24 -p tcp --dport 23 -j DROP
# Log blocked attempts for monitoring
iptables -A FORWARD -d 192.168.100.0/24 -p tcp --dport 23 -j LOG --log-prefix "BLOCKED_TELNET_CAMERA: "
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
