id: "SI-10(04)" title: "Timing Interactions" family: "SI" family_name: "System and Information Integrity" sort_id: "si-10.04" priority: "P1" implementation_level: "system" parent: "SI-10" enhancement: True
Statement
Account for timing interactions among system components in determining appropriate responses for invalid inputs.
Guidance
In addressing invalid system inputs received across protocol interfaces, timing interactions become relevant, where one protocol needs to consider the impact of the error response on other protocols in the protocol stack. For example, 802.11 standard wireless network protocols do not interact well with Transmission Control Protocols (TCP) when packets are dropped (which could be due to invalid packet input). TCP assumes packet losses are due to congestion, while packets lost over 802.11 links are typically dropped due to noise or collisions on the link. If TCP makes a congestion response, it takes the wrong action in response to a collision event. Adversaries may be able to use what appear to be acceptable individual behaviors of the protocols in concert to achieve adverse effects through suitable construction of invalid input. The invalid inputs are those related to the information inputs defined by the organization in the base control ( SI-10).
Assessment Objective
timing interactions among system components are accounted for in determining appropriate responses for invalid inputs.
System and information integrity policy
system and information integrity procedures
procedures addressing information input validation
system design documentation
system configuration settings and associated documentation
system audit records
system security plan
other relevant documents or records
Organizational personnel responsible for information input validation
organizational personnel with information security responsibilities
system/network administrators
system developer
Organizational processes for determining appropriate responses to invalid inputs
automated mechanisms supporting and/or implementing responses to invalid inputs