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SC-31: COVERT CHANNEL ANALYSIS

NOT SELECTED FOR INDUSTRIAL CONTROL SYSTEMS

The organization:

    • a. Performs a covert channel analysis to identify those aspects of communications within the information system that are potential avenues for covert [Selection (one or more): storage; timing] channels; and
    • b. Estimates the maximum bandwidth of those channels.

SUPPLEMENTAL GUIDANCE

Developers are in the best position to identify potential areas within systems that might lead to covert channels. Covert channel analysis is a meaningful activity when there is the potential for unauthorized information flows across security domains, for example, in the case of information systems containing export-controlled information and having connections to external networks (i.e., networks not controlled by organizations). Covert channel analysis is also meaningful for multilevel secure (MLS) information systems, multiple security level (MSL) systems, and cross-domain systems.

CONTROL ENHANCEMENTS

SC-31 (1) COVERT CHANNEL ANALYSIS | TEST COVERT CHANNELS FOR EXPLOITABILITY

The organization tests a subset of the identified covert channels to determine which channels are exploitable.

Supplemental Guidance: NONE

SC-31 (2) COVERT CHANNEL ANALYSIS | MAXIMUM BANDWIDTH

The organization reduces the maximum bandwidth for identified covert [Selection (one or more); storage; timing] channels to [Assignment: organization-defined values].

Supplemental Guidance:

Information system developers are in the best position to reduce the maximum bandwidth for identified covert storage and timing channels.

SC-31 (3) COVERT CHANNEL ANALYSIS | MEASURE BANDWIDTH IN OPERATIONAL ENVIRONMENTS

The organization measures the bandwidth of [Assignment: organization-defined subset of identified covert channels] in the operational environment of the information system.

Supplemental Guidance:

This control enhancement addresses covert channel bandwidth in operational environments versus developmental environments. Measuring covert channel bandwidth in operational environments helps organizations to determine how much information can be covertly leaked before such leakage adversely affects organizational missions/business functions. Covert channel bandwidth may be significantly different when measured in those settings that are independent of the particular environments of operation (e.g., laboratories or development environments).

REFERENCES:

  • NIST Special Publication 800-82 | GUIDE TO INDUSTRIAL CONTROL SYSTEMS (ICS) SECURITY