CAPEC-700 Network Boundary Bridging

An adversary which has gained elevated access to network boundary devices may use these devices to create a channel to bridge trusted and untrusted networks. Boundary devices do not necessarily have to be on the network’s edge, but rather must serve to segment portions of the target network the adversary wishes to cross into.

Network boundary devices are network devices such as routers and firewalls which segment networks by restricting certain types of traffic from flowing through the device. Network boundary devices are often directly accessible through a portal page for management purposes. An adversary’s goal when conducting network boundary bridging is to connect networks which are being segmented by the device. To do so, the adversary must first compromise the network boundary device.

1. [Explore] [Identify potential targets] An adversary identifies network boundary devices that can be compromised. 2. [Experiment] [Compromise targets] The adversary must compromise the identified targets in the previous step. 3. [Exploit] [Bridge Networks] The adversary changes the configuration of the compromised network device to connect the networks the device was segmenting. Depending on the type of network boundary device and its capabilities, bridging can be implemented using various methods.

• The adversary must have control of a network boundary device.

• [Medium] The adversary must understand how to manage the target network device to create or edit policies which will bridge networks.

• Confidentiality, Access Control: Read Data, Bypass Protection Mechanism • Integrity, Authorization: Alter Execution Logic, Hide Activities

• Design: Ensure network devices are storing credentials in encrypted stores • Design: Follow the principle of least privilege and restrict administrative duties to as few accounts as possible. Ensure these privileged accounts are secured with strong credentials which do not overlap with other network devices. • Configuration: When possible, configure network boundary devices to use MFA. • Configuration: Change the default configuration for network devices to harden their security profiles. Default configurations are often enabled with insecure features to allow ease of installation and management. However, these configurations can be easily discovered and exploited by adversaries. • Implementation: Perform integrity checks on audit logs for network device management and review them to identify abnormalities in configurations. • Implementation: Prevent network boundary devices from being physically accessed by unauthorized personnel to prevent tampering.