# AC-21 Information Sharing

NIST SP 800-53 control. Family: AC Access Control. Function: preventative. Baselines: moderate, high. Mapping licence: CC BY-SA 4.0.

Statement: a. Enable authorized users to determine whether access authorizations assigned to a sharing partner match the information’s access and use restrictions for [Assignment: organization-defined information sharing circumstances where user discretion is required]; and b. Employ [Assignment: organization-defined automated mechanisms or manual processes] to assist users in making information sharing and collaboration decisions.
Guidance: Information sharing applies to information that may be restricted in some manner based on some formal or administrative determination. Examples of such information include, contract-sensitive information, classified information related to special access programs or compartments, privileged information, proprietary information, and personally identifiable information. Security and privacy risk assessments as well as applicable laws, regulations, and policies can provide useful inputs to these determinations. Depending on the circumstances, sharing partners may be defined at the individual, group, or organizational level. Information may be defined by content, type, security category, or special access program or compartment. Access restrictions may include non-disclosure agreements (NDA). Information flow techniques and security attributes may be used to provide automated assistance to users making sharing and collaboration decisions.

## Enhancements (2)
- AC-21(01) Automated Decision Support
- AC-21(02) Information Search and Retrieval
Each enhancement's statement: /api/v1/controls/AC-21?fields=enhancements

## Patterns that use it (5)
- Important (3): SP-029 Zero Trust Architecture; SP-030 API Security; SP-039 Client-Side Encryption and Data Privacy
- Standard (2): SP-032 Modern Authentication; SP-044 SaaS Identity Lifecycle Management

## Clauses by framework (18 frameworks)
- iso_27002_2022: 5.15
- cobit_2019: DSS05
- nis2: Art. 21(2)(i)
- mas_trm: 9
- bsi_grundschutz: ORP.4
- bio2: 5.15
- rbi_csf: Annex1.15
- dnb_good_practice: DNB.18.5
- qatar_nia: AC
- uae_ia: T9
- bog_cisd: CISD-VIII
- bcbs_239: Principle 11
- ffiec_is: II.C.13
- nydfs_500: 500.18
- cmmc_2: AC
- isae_3402: Clause 8
- naic_ds: 8
- dpdpa: Rules.15

## More
- This control as JSON, with guidance and ATT&CK techniques: /api/v1/controls/AC-21
- Clauses only: /api/v1/controls/AC-21?fields=mappings
- Page for people: /controls/ac-21/
- Found an error? Open an issue at https://github.com/opensecurityarchitecture/osa-data/issues with the id, what OSA says and what the source says.