Security requirement
Check the validity of the following information inputs: [Organization-defined: information inputs].
Discussion
Checking the valid syntax and semantics of system inputs—including character set, length, numerical range, and acceptable values—verifies that inputs match specified definitions for format and content. Valid inputs are likely to vary from field to field within a software application. Applications typically follow well-defined protocols that use structured messages (i.e., commands or queries) to communicate between software modules or system components. Structured messages can contain raw or unstructured data interspersed with metadata or control information. If software applications use attacker-supplied inputs to construct structured messages without properly encoding such messages, the attacker could insert malicious commands or special characters that can cause the data to be interpreted as control information or metadata. Consequently, the module or component that receives the corrupted output will perform incorrect operations or otherwise interpret the data incorrectly. Prescreening inputs prior to passing them to interpreters prevents content from being unintentionally interpreted as commands. Input validation ensures accurate and correct inputs and prevents attacks, such as cross-site scripting and a variety of injection attacks. This requirement is sourced to a control tailored out of the SP 800-53B .13 moderate baseline in SP 800-171.
Tailoring decisions required
Resolve these values through the governing organization’s approved tailoring and risk-management process before declaring the requirement implemented.
Protection strategies supported
These classifications are carried from the official SP 800-172 OSCAL record and help explain the enhanced requirement’s defensive purpose.
Implementation perspective
Treat Information Input Validation as an enhanced CUI protection outcome for elevated threat conditions that must be reflected in the system boundary, documented implementation, operational behavior, and assessment evidence. Pay particular attention to flaw remediation, malicious-code protection, monitoring, integrity, and trustworthy handling of CUI.
- Confirm the federal agency selected this enhanced requirement for the critical program or high-value asset and identify the CUI system components, services, users, and external connections in scope.
- Resolve every organization-defined parameter through an approved governance and tailoring process.
- Map each clause of the requirement to an accountable owner, implementation mechanism, and evidence source.
- Verify that inherited and shared implementations are supported by current provider evidence and responsibility boundaries.
- Collect evidence during normal operation and review changes, exceptions, and deficiencies on a risk-based cadence.
Questions to ask
- Which critical-program or high-value-asset CUI, data flows, users, and services are protected by this enhanced requirement?
- Which portions are implemented locally, inherited, shared, or not applicable, and what evidence supports that determination?
- Do the system security plan, deployed configuration, operating process, and assessment evidence tell the same story?
- What change, incident, or threshold should trigger reassessment?
Evidence and validation
- patch and remediation records
- malware protection configuration
- monitoring alerts and response records
- integrity validation and exception reports
Common failure patterns
- patch compliance hiding unsupported assets
- alerts generated without response ownership
- exceptions that never expire
- integrity monitoring excluding critical configurations
Assessment objectives and methods
Assessment objectives (1)
the validity of the [Organization-defined: information inputs] is checked.
Examine
- System and information integrity policy
- system and information integrity procedures
- access control policy and procedures
- separation of duties policy and procedures
- procedures addressing information input validation
- documentation for automated tools and applications to verify the validity of information
- list of information inputs requiring validity checks
- system design documentation
- system configuration settings and associated documentation
- system audit records
- system security plan
- other relevant documents or records
Interview
- Personnel responsible for information input validation
- personnel with information security responsibilities
- system/network administrators
- system developers
Test
- Mechanisms supporting and/or implementing validity checks on information inputs
Source NIST SP 800-53 controls
These controls are referenced by the official SP 800-172 Rev. 3 OSCAL record. Open the corresponding control pages for complete control text, enhancements, D3FEND mappings, and related learning.
Authoritative sources
- NIST SP 800-172 Revision 3 official publication ↗
- NIST SP 800-172A Revision 3 official publication ↗
- NIST OSCAL Content release used for this import ↗
Bare Metal Cyber is an independent educational publisher and is not affiliated with or endorsed by NIST. The official publications, the responsible federal agency, and the governing contract or agreement determine applicability, tailoring, assessment depth, and required implementation.