{"licence":{"name":"CC BY-SA 4.0","spdx":"CC-BY-SA-4.0","url":"https://creativecommons.org/licenses/by-sa/4.0/","attribution":"Atlas, a bilingual technical dictionary (https://cmaintz.github.io/tech-atlas/)"},"id":"security/cia-triad","url":{"en":"https://cmaintz.github.io/tech-atlas/en/terms/security/cia-triad/","da":"https://cmaintz.github.io/tech-atlas/da/terms/security/cia-triad/"},"term":{"en":"CIA triad","da":"CIA-triaden"},"aka":{"en":["CIA model"],"da":["CIA-modellen"]},"domain":["security"],"cluster":"fundamentals","layer":"governance","status":"current","summary":{"en":"The three pillars of information security - confidentiality, integrity and availability.","da":"Informationssikkerhedens tre søjler - fortrolighed, integritet og tilgængelighed."},"body":{"formal":{"en":"A model that states the goals of information security as three properties - confidentiality, integrity and availability - which every protective measure should serve. Standards such as ISO 27000 add further properties, for example authenticity and non-repudiation.","da":"En model, der beskriver målene for informationssikkerhed som tre egenskaber - fortrolighed, integritet og tilgængelighed - som ethvert beskyttende tiltag bør tjene. Standarder som ISO 27000 tilføjer flere egenskaber, fx ægthed og uafviselighed."},"plain":{"en":"Like a three-legged stool - if any one leg is missing, the whole thing falls over.","da":"Som en skammel med tre ben - mangler blot ét af dem, vælter det hele."},"inPractice":{"en":"Before a Danish municipality takes a new case system into use, its information security coordinator asks three questions - who may see the cases, what if the data is wrong, and what if the system is down for a day?","da":"Før en kommune tager et nyt sagssystem i brug, stiller den informationssikkerhedsansvarlige tre spørgsmål - hvem må se sagerne, hvad hvis data er forkerte, og hvad hvis systemet er nede en hel dag?"},"whyItMatters":{"en":"It gives everyone, from engineers to the board, a shared way to say what is at stake, so no side of protection is forgotten.","da":"Den giver alle, fra teknikere til bestyrelse, et fælles sprog for, hvad der står på spil, så ingen side af beskyttelsen bliver glemt."}},"deepDive":{"en":"The triad has no single inventor. Saltzer and Schroeder's 1975 paper \"The Protection of Information in Computer Systems\" grouped security violations into unauthorised release of information, unauthorised modification and unauthorised denial of use, which map onto confidentiality, integrity and availability. The three words became fixed in US government doctrine and later in the Federal Information Security Management Act, whose definitions FIPS 199 reuses. ISO/IEC 27000 defines information security as the preservation of confidentiality, integrity and availability, and notes that other properties such as authenticity, accountability, non-repudiation and reliability can also be involved. NIS2 Art. 6(2) lists availability, authenticity, integrity and confidentiality, effectively a four-property model.\n\nEach leg has its own classical formal model. Bell-LaPadula (1973) formalises confidentiality with \"no read up, no write down\"; Biba (1977) inverts the rules for integrity; Clark-Wilson (1987) models commercial integrity with well-formed transactions and separation of duties. Availability has no comparable lattice model and is usually handled with reliability engineering, capacity planning and continuity planning rather than access rules. That asymmetry is one reason availability was long treated as an operations problem rather than a security one, until ransomware and DDoS made it central.\n\nThe main practical use is categorisation. FIPS 199 rates the potential impact of a loss of each property separately as low, moderate or high, giving a security category such as {(confidentiality, moderate), (integrity, high), (availability, low)}; FIPS 200 then applies the high-water mark to select an SP 800-53 baseline. ISO/IEC 27002:2022 tags each of its 93 controls with the properties it protects (#Confidentiality, #Integrity, #Availability), and many risk methods score consequence per property, so that a public website can be low on confidentiality yet high on integrity and availability.\n\nThe model has known limits. Donn Parker's hexad (1998) added possession or control, authenticity and utility, arguing, for example, that a stolen but still encrypted laptop is a loss of possession without a loss of confidentiality. The properties also conflict: more copies improve availability but widen the confidentiality exposure, and strict integrity checks can block service. The triad describes goals, not controls or threats, and says nothing about privacy in the GDPR sense, safety in operational technology, where availability and integrity usually dominate, or accountability. It works best as a checklist of questions per asset rather than as a complete theory of security.","da":"Triaden har ingen enkelt ophavsmand. Saltzer og Schroeders artikel \"The Protection of Information in Computer Systems\" fra 1975 inddelte sikkerhedsbrud i uautoriseret frigivelse af information, uautoriseret ændring og uautoriseret nægtelse af brug, hvilket svarer til fortrolighed, integritet og tilgængelighed. De tre ord blev fast inventar i amerikansk forvaltningsdoktrin og senere i Federal Information Security Management Act, hvis definitioner FIPS 199 genbruger. ISO/IEC 27000 definerer informationssikkerhed som bevarelse af fortrolighed, integritet og tilgængelighed og bemærker, at andre egenskaber som ægthed, ansvarlighed, uafviselighed og pålidelighed også kan indgå. NIS2 art. 6, nr. 2, nævner tilgængelighed, autenticitet, integritet og fortrolighed, i praksis en model med fire egenskaber.\n\nHvert ben har sin egen klassiske formelle model. Bell-LaPadula (1973) formaliserer fortrolighed med \"no read up, no write down\"; Biba (1977) vender reglerne om for integritet; Clark-Wilson (1987) modellerer kommerciel integritet med velformede transaktioner og funktionsadskillelse. Tilgængelighed har ingen tilsvarende gittermodel og håndteres normalt med pålidelighedsteknik, kapacitetsplanlægning og beredskabsplanlægning frem for adgangsregler. Den asymmetri er en af grundene til, at tilgængelighed længe blev set som et driftsproblem og ikke et sikkerhedsproblem, indtil ransomware og DDoS gjorde den central.\n\nDen vigtigste praktiske anvendelse er kategorisering. FIPS 199 vurderer den mulige konsekvens af tab af hver egenskab for sig som low, moderate eller high, hvilket giver en sikkerhedskategori som {(confidentiality, moderate), (integrity, high), (availability, low)}; FIPS 200 anvender derefter high-water mark-princippet til at vælge en baseline i SP 800-53. ISO/IEC 27002:2022 mærker hver af sine 93 kontroller med de egenskaber, den beskytter (#Confidentiality, #Integrity, #Availability), og mange risikometoder vurderer konsekvens pr. egenskab, så en offentlig hjemmeside kan være lav på fortrolighed, men høj på integritet og tilgængelighed.\n\nModellen har kendte begrænsninger. Donn Parkers hexade (1998) tilføjede besiddelse eller kontrol, ægthed og anvendelighed og argumenterede fx for, at en stjålet, men stadig krypteret bærbar er et tab af besiddelse uden tab af fortrolighed. Egenskaberne konflikter også: flere kopier forbedrer tilgængeligheden, men øger eksponeringen for fortroligheden, og stramme integritetstjek kan blokere driften. Triaden beskriver mål, ikke kontroller eller trusler, og siger intet om privatliv i GDPR-forstand, om safety i operationel teknologi (OT), hvor tilgængelighed og integritet som regel vejer tungest, eller om ansvarlighed. Den fungerer bedst som en tjekliste af spørgsmål pr. aktiv og ikke som en fuldstændig teori om sikkerhed."},"edges":[{"type":"part-of","to":"security/cyber-and-information-security","confidence":"high","strength":"normal"}],"depth":0,"sources":[{"title":"Cyber Security Fast Track - Ordliste","tier":"course-material"},{"title":"NIST SP 800-12 Rev. 1 - An Introduction to Information Security","tier":"standard","publisher":"NIST"}],"draft":true}