{"data":{"id":"AC-21","name":"Information Sharing","family":"AC","family_name":"Access Control","withdrawn":false,"description":"a. Enable authorized users to determine whether access authorizations assigned to a sharing partner match the information’s access and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\nb. Employ [Assignment: organization-defined automated mechanisms or manual processes] to assist users in making information sharing and collaboration decisions.","supplemental_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":[{"id":"AC-21(01)","name":"Automated Decision Support","statement":"Employ [Assignment: organization-defined automated mechanisms] to enforce information-sharing decisions by authorized users based on access authorizations of sharing partners and access restrictions on information to be shared.","baselines":[]},{"id":"AC-21(02)","name":"Information Search and Retrieval","statement":"Implement information search and retrieval services that enforce [Assignment: organization-defined information sharing restrictions].","baselines":[]}],"baseline_low":false,"baseline_moderate":true,"baseline_high":true,"nist_800_53":{"rev5":{"id":"AC-21","name":"Information Sharing","description":"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\nb. Employ [Assignment: organization-defined automated mechanisms or manual processes] to assist users in making information sharing and collaboration decisions.","discussion":"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.","related_controls":["AC-03","AC-04","AC-16","PT-02","PT-07","RA-03","SC-15"],"baseline_low":false,"baseline_moderate":true,"baseline_high":true,"baseline_privacy":false,"new_in_rev5":false,"changes_from_rev4":"No significant changes from Rev 4."}},"compliance_mappings":{"iso_27001_2022":[],"iso_27002_2022":["5.15"],"cobit_2019":["DSS05"],"pci_dss_v4":[],"nist_csf_2":[],"cis_controls_v8":[],"soc2_tsc":[],"finos_ccc":[],"iso_42001_2023":[],"iec_62443":[],"asd_e8":[],"nis2":["Art. 21(2)(i)"],"apra_cps_234":[],"mas_trm":["9"],"pra_op_resilience":[],"bsi_grundschutz":["ORP.4"],"anssi":[],"osfi_b13":[],"finma_circular":[],"gdpr":[],"dora":[],"bio2":["5.15"],"rbi_csf":["Annex1.15"],"fisc":[],"lgpd_bcb":[],"hkma_tme1":[],"mlps_2":[],"dnb_good_practice":["DNB.18.5"],"cra":[],"swift_cscf":[],"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"],"nerc_cip":[],"nrc_73_54":[],"tsa_psd":[],"ieee_1686":[],"ferc_cip":[],"doe_c2m2":[],"api_1164":[],"awia":[],"iaea_nss":[],"pci_pts":[],"fips_140":[],"cbest":[],"tiber_eu":[],"pci_hsm":[],"common_criteria":[],"isae_3402":["Clause 8"],"fca_sysc_13":[],"fda_21_cfr_11":[],"fda_cyber":[],"hitrust_csf":[],"iso_27799":[],"lloyds_ms":[],"naic_ds":["8"],"nhs_dspt":[],"pra_ss1_23":[],"solvency_ii":[],"owasp_masvs_v2":[],"csa_ccm_v4":[],"csa_aicm":[],"ccss_v9":[],"mica":[],"basel_sco60":[],"bssc":[],"sec_custody_digital":[],"dpdpa":["Rules.15"]},"attack_techniques":[{"id":"T1213","name":"Data from Information Repositories","tactics":["collection"],"mapping_type":"mitigates","mapping_rationale":"Information sharing controls that enable users to verify sharing partner access authorizations ensure that data from information repositories is only accessible to properly authorized recipients, limiting unauthorized collection."},{"id":"T1213.001","name":"Confluence","tactics":["collection"],"mapping_type":"mitigates","mapping_rationale":"Sharing controls on Confluence spaces that verify recipient authorization before enabling access prevent adversaries from exploiting overly broad sharing permissions to collect sensitive knowledge base content."},{"id":"T1213.002","name":"Sharepoint","tactics":["collection"],"mapping_type":"mitigates","mapping_rationale":"Information sharing mechanisms on SharePoint that require users to verify sharing partner access levels prevent adversaries from accessing documents through improperly authorized sharing configurations."},{"id":"T1213.004","name":"Customer Relationship Management Software","tactics":["collection"],"mapping_type":"mitigates","mapping_rationale":"Sharing controls on CRM platforms that verify partner access authorizations before enabling data access prevent adversaries from collecting customer data through unauthorized or overly permissive sharing."},{"id":"T1213.005","name":"Messaging Applications","tactics":["collection"],"mapping_type":"mitigates","mapping_rationale":"Information sharing controls on messaging applications that verify recipient authorizations prevent adversaries from accessing sensitive conversations and shared files through improperly scoped sharing permissions."}],"metadata":{"last_reviewed":"2026-02-19","review_notes":"Generated from NIST SP 800-53 Rev 5 with compliance mappings from framework-coverage data","mapping_status":"complete"},"function":"preventative","used_by_patterns":["SP-029","SP-030","SP-032","SP-039","SP-044"]}}