AC-17

AC-17 REMOTE ACCESS

Overview

Number	Title	Impact	Priority	Subject Area
AC-17	Remote Access	LOW	P1	Access Control

Instructions
The organization: AC-17a. Establishes and documents usage restrictions, configuration/connection requirements, and implementation guidance for each type of remote access allowed; and AC-17b. Authorizes remote access to the information system prior to allowing such connections.

Guidance
Remote access is access to organizational information systems by users (or processes acting on behalf of users) communicating through external networks (e.g., the Internet). Remote access methods include, for example, dial-up, broadband, and wireless. Organizations often employ encrypted virtual private networks (VPNs) to enhance confidentiality and integrity over remote connections. The use of encrypted VPNs does not make the access non-remote; however, the use of VPNs, when adequately provisioned with appropriate security controls (e.g., employing appropriate encryption techniques for confidentiality and integrity protection) may provide sufficient assurance to the organization that it can effectively treat such connections as internal networks. Still, VPN connections traverse external networks, and the encrypted VPN does not enhance the availability of remote connections. Also, VPNs with encrypted tunnels can affect the organizational capability to adequately monitor network communications traffic for malicious code. Remote access controls apply to information systems other than public web servers or systems designed for public access. This control addresses authorization prior to allowing remote access without specifying the formats for such authorization. While organizations may use interconnection security agreements to authorize remote access connections, such agreements are not required by this control. Enforcing access restrictions for remote connections is addressed in AC-3.

Guidance

Remote access is access to organizational information systems by users (or processes acting on behalf of users) communicating through external networks (e.g., the Internet). Remote access methods include, for example, dial-up, broadband, and wireless. Organizations often employ encrypted virtual private networks (VPNs) to enhance confidentiality and integrity over remote connections. The use of encrypted VPNs does not make the access non-remote; however, the use of VPNs, when adequately provisioned with appropriate security controls (e.g., employing appropriate encryption techniques for confidentiality and integrity protection) may provide sufficient assurance to the organization that it can effectively treat such connections as internal networks. Still, VPN connections traverse external networks, and the encrypted VPN does not enhance the availability of remote connections. Also, VPNs with encrypted tunnels can affect the organizational capability to adequately monitor network communications traffic for malicious code. Remote access controls apply to information systems other than public web servers or systems designed for public access. This control addresses authorization prior to allowing remote access without specifying the formats for such authorization. While organizations may use interconnection security agreements to authorize remote access connections, such agreements are not required by this control. Enforcing access restrictions for remote connections is addressed in AC-3.

Enhancements

AC-17 (1) Automated Monitoring / Control

MODERATE

Automated monitoring and control of remote access sessions allows organizations to detect cyber attacks and also ensure ongoing compliance with remote access policies by auditing connection activities of remote users on a variety of information system components (e.g., servers, workstations, notebook computers, smart phones, and tablets).

The information system monitors and controls remote access methods.

AC-17 (2) Protection Of Confidentiality / Integrity Using Encryption

MODERATE

The encryption strength of mechanism is selected based on the security categorization of the information.

The information system implements cryptographic mechanisms to protect the confidentiality and integrity of remote access sessions.

AC-17 (3) Managed Access Control Points

MODERATE

Limiting the number of access control points for remote accesses reduces the attack surface for organizations. Organizations consider the Trusted Internet Connections (TIC) initiative requirements for external network connections.

The information system routes all remote accesses through Assignment: organization-defined number managed network access control points.

AC-17 (4) Privileged Commands / Access

MODERATE

The organization:

AC-17 (4)(a)

Authorizes the execution of privileged commands and access to security-relevant information via remote access only for Assignment: organization-defined needs; and

AC-17 (4)(b)

Documents the rationale for such access in the security plan for the information system.

AC-17 (5) Monitoring For Unauthorized Connections

Withdrawn: Incorporated into SI-4.

AC-17 (6) Protection Of Information

The organization ensures that users protect information about remote access mechanisms from unauthorized use and disclosure.

AC-17 (7) Additional Protection For Security Function Access

Withdrawn: Incorporated into AC-3 (10).

AC-17 (8) Disable Nonsecure Network Protocols

Withdrawn: Incorporated into CM-7.

AC-17 (9) Disconnect / Disable Access

This control enhancement requires organizations to have the capability to rapidly disconnect current users remotely accessing the information system and/or disable further remote access. The speed of disconnect or disablement varies based on the criticality of missions/business functions and the need to eliminate immediate or future remote access to organizational information systems.

The organization provides the capability to expeditiously disconnect or disable remote access to the information system within Assignment: organization-defined time period.