Requirement text: SI.2.216: Monitor organizational systems, including inbound and outbound
communications traffic, to detect attacks and indicators of potential attacks.
DISCUSSION FROM SOURCE: DRAFT NIST SP 800-171 R2
System monitoring includes external and internal monitoring. External monitoring includes
the observation of events occurring at the system boundary (i.e., part of perimeter defense
and boundary protection). Internal monitoring includes the observation of events occurring
within the system. Organizations can monitor systems, for example, by observing audit
record activities in real time or by observing other system aspects such as access patterns,
characteristics of access, and other actions. The monitoring objectives may guide
determination of the events. System monitoring capability is achieved through a variety of
tools and techniques (e.g., intrusion detection systems, intrusion prevention systems,
malicious code protection software, scanning tools, audit record monitoring software,
network monitoring software). Strategic locations for monitoring devices include selected
perimeter locations and near server farms supporting critical applications, with such devices
being employed at managed system interfaces. The granularity of monitoring information
collected is based on organizational monitoring objectives and the capability of systems to
support such objectives.
System monitoring is an integral part of continuous monitoring and incident response
programs. Output from system monitoring serves as input to continuous monitoring and
incident response programs. A network connection is any connection with a device that
communicates through a network (e.g., local area network, Internet). A remote connection
is any connection with a device communicating through an external network (e.g., the
Internet). Local, network, and remote connections can be either wired or wireless.
Unusual or unauthorized activities or conditions related to inbound/outbound
communications traffic include internal traffic that indicates the presence of malicious code
in systems or propagating among system components, the unauthorized exporting of
information, or signaling to external systems. Evidence of malicious code is used to identify
potentially compromised systems or system components. System monitoring requirements,
including the need for specific types of system monitoring, may be referenced in other
requirements.
NIST SP 800-94 provides guidance on intrusion detection and prevention systems.
CMMC CLARIFICATION
Organizations should leverage their monitoring systems to look for indicators of attacks.
Think of indicators of attack as a series of actions that an adversary conducts in advance of
an attack. Indicators of attack concern the steps involved and the intent of the adversary.
Indicators of attacks on organizational systems may include:
• internal traffic that indicates the presence of malicious code;
• malicious code detected during non-business hours;
• the unauthorized data leaving the organization; and
• communicating to external information systems.
To detect attacks and indicators of attacks with success, deploy monitoring devices. Place
these devices within the systems at strategic points to collect essential information. Strategic
points include internal and external system boundaries. The organization should monitor
both inbound traffic and outbound traffic.
Example
You are in charge of IT operations at your organization. You look for attacks to your network.
To do this, you monitor all organizational systems. You also watch communications to and
from your machines. You look for indicators, or things that don’t look like they should. These
indicators can show up in many places on your network. You should monitor important
places on your network. These places might include:
• perimeter locations, or locations your networks connect to the internet;
• machines that have important software or data on them that attackers might want to
access; and
• your remote connections which may be a way to gain access to your network from
the outside.
Perform additional monitoring when you find an indicator, or something that doesn’t
perform as it should. This extra monitoring should tell you if it is a current or potential
attack.
Set up your monitoring activities so that they support your organization’s planning. Develop
your monitoring requirements as part of your organization’s security activities. Ensure that
your monitoring activities meet the security needs of your organization.
References
• NIST SP 800-171 Rev 1 3.14.6
• CIS Controls v7.1 12.6
• NIST CSF v1.1 DE.CM-1
• CERT RMM v1.2 MON:SG1.SP3
• NIST SP 800-53 Rev 4 SI-4