SC.L2-3.13.7 Split Tunneling

Prevent remote devices from simultaneously establishing non-remote connections with organizational systems and communicating via some other connection to resources in external networks (i.e., split tunneling).

Source: NIST SP 800-171 Rev 2 3.13.7

Discussion: Split tunneling might be desirable by remote users to communicate with local system resources such as printers or file servers. However, split tunneling allows unauthorized external connections, making the system more vulnerable to attack and to exfiltration of organizational information. This requirement is implemented in remote devices (e.g., notebook computers, smart phones, and tablets) through configuration settings to disable split tunneling in those devices, and by preventing configuration settings from being readily configurable by users. This requirement is implemented in the system by the detection of split tunneling (or of configuration settings that allow split tunneling) in the remote device, and by prohibiting the connection if the remote device is using split tunneling.

Assessment Objectives:

Determine if:

• [a] remote devices are prevented from simultaneously establishing non-remote connections with the system and communicating via some other connection to resources in external networks (i.e., split tunneling).

Examine: [SELECT FROM: System and communications protection policy; procedures addressing boundary protection; security plan; system design documentation; system hardware and software; system architecture; system configuration settings and associated documentation; system audit logs and records; other relevant documents or records].

Interview: [SELECT FROM: System or network administrators; personnel with information security responsibilities; system developer; personnel with boundary protection responsibilities].

Test: [SELECT FROM: Mechanisms implementing boundary protection capability; mechanisms supporting or restricting non-remote connections].

SPRS Score: 1

POA&M Allowed: Yes