Chinese APT: A Master of Exploiting Edge Devices

Chinese APT actors have shifted focus to exploiting High-Value Device Interfaces (HDVIs) and edge devices like firewalls, VPNs, and routers over the past 3 years

HDVIs are attractive targets because:

• They are closed platforms with limited monitoring/antivirus capabilities
• Often lack modern exploit mitigations
• Difficult to patch due to 24/7 operational requirements
• Frequently reach end-of-life status while still in use
• Interface between internal networks and internet

Common attack patterns include:

• Using pole-knocking backdoors for persistence
• Compromising devices as C2 infrastructure
• Implementing malware to intercept traffic and steal data
• Leveraging devices for lateral movement

Notable examples observed:

• Barracuda email security gateway attacks
• ZLVPN compromises in Taiwan
• Exploitation of Cisco routers by Black Tech group
• Targeting of military entities through HDVI vulnerabilities

Key challenges for defenders:

• Limited incident response capabilities on devices
• Difficulty retrieving malware samples
• Complex patch management requirements
• Lack of EDR solutions for edge devices
• Hidden C2 traffic in legitimate device communications

Recommendations include:

• Improved monitoring of edge device traffic
• Regular security assessments of HDVIs
• Strict access control and authentication
• Network segmentation
• Rapid patch deployment when available