CTEM-EXP-1 - Directly Connected Internal System
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Directly Connected Internal System refers to a system that has been discovered to be accessible from the internet and is believed to be directly connected to the internal network. These systems are often hosted in a DMZ (demilitarized zone) or similar perimeter network that serves as a buffer between the internal network and the public internet. Examples include websites, email servers, Citrix gateways, or remote access gateways.
Characteristics of a Directly Connected Internal System
- Internet Accessibility: The system is exposed to the public internet, often due to a requirement for external access, such as hosting public-facing services or providing remote access for employees.
- Internal Network Connectivity: The system is connected to the internal network, typically through a DMZ or other semi-trusted network zone, meaning that it has the ability to communicate with other systems within the internal environment.
- Critical Service Role: These systems often play a crucial role in enabling business operations, such as hosting websites, managing email, or providing remote access, making them essential for productivity.
Common Methods of Discovery
Directly connected internal systems are typically discovered through:
- Internet Scanning Tools: Tools such as Shodan, Censys, or Nmap are commonly used to scan the internet and identify publicly accessible systems, including those connected to internal networks.
- Third-Party Threat Intelligence: Threat intelligence services may detect exposed systems that are believed to be part of an organization's internal infrastructure.
- Network and Port Scans: Scanning of network ports and services may reveal systems that are both externally accessible and connected to internal network segments.
Risks and Impact
The risks associated with directly connected internal systems include:
- Lateral Movement: If an attacker compromises the system, they may use it as a foothold to move laterally into the internal network, potentially compromising other systems and gaining deeper access to sensitive data.
- Data Breach: Sensitive information hosted on the system or accessible through its internal connections may be at risk if the system is compromised.
- Service Disruption: Compromised systems can lead to disruptions of critical services, such as email, remote access, or public-facing applications, impacting business continuity.
- Increased Attack Surface: The exposure of internal systems to the internet increases the organization's attack surface, providing more opportunities for attackers to exploit vulnerabilities.
Key Considerations for Threat Exposure Management
Managing directly connected internal systems requires a combination of technical controls, monitoring, and strict access policies:
- Network Segmentation and Isolation: Implement strong network segmentation to limit the connectivity between directly connected systems and the internal network. Ensure that any connections are tightly controlled and monitored.
- Access Controls and Hardening: Enforce strict access controls for internet-facing systems, such as multi-factor authentication (MFA), and harden system configurations to reduce vulnerabilities.
- Monitoring and Intrusion Detection: Continuously monitor these systems for signs of compromise, unauthorized access, or unusual activity. Implement intrusion detection systems (IDS) to identify potential threats.
- Vulnerability Management: Regularly update and patch directly connected systems to mitigate known vulnerabilities. Conduct vulnerability assessments to identify and address potential weaknesses.
- Incident Response Planning: Develop an incident response plan that specifically addresses the compromise of directly connected internal systems. Include procedures for isolating compromised systems, preventing lateral movement, and remediating vulnerabilities.
Directly connected internal systems present a significant risk to the organization's overall security posture due to their dual role of public accessibility and internal network connectivity. Effective threat exposure management requires robust access controls, proactive monitoring, and comprehensive incident response capabilities to reduce the risk of compromise and lateral movement into the internal network.