Microsoft Entra Client Access Token

Detects Microsoft Entra (formerly Azure AD) client access token patterns. This pattern is based on a Microsoft Purview built-in sensitive information type. Users already running Purview may prefer to enable the built-in SIT directly, or use this version as a starting point for customisation.

Type: regex
Engine: universal
Confidence: medium
Confidence justification: Medium confidence: JWT format is common across many identity providers. Corroborative evidence keywords specific to Microsoft Entra improve accuracy. Added context gating and exclusion rules improve precision and reduce incidental matches.
Detection quality: Verified
Jurisdictions: global
Regulations: Criminal Code Act 1995 (Cth)
Frameworks: CIS Controls, ISO 27001, NIST CSF, PCI-DSS, SOC 2
Data categories: credentials, security
Scope: specific
Risk rating: 10
Platform compatibility: Purview: Compatible, GCP DLP: Compatible, Macie: Compatible, Zscaler: Compatible, Palo Alto: Compatible, Netskope: Compatible

Pattern

\beyJ[A-Za-z0-9_-]{20,}\.[A-Za-z0-9_-]{20,}\.[A-Za-z0-9_-]{20,}\b

Corroborative evidence keywords

Entra, Azure AD, access_token, bearer, login.microsoftonline.com, Microsoft identity, OAuth, client credentials, api key, api_key, apikey, access key, access token, auth token, authorization, conn str, connection string, connectionstring, cookie, credential (+44 more)

Proximity: 300 characters

Should match

eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwiYXVkIjoiMDAwMDAwMDAtMDAwMC0wMDAwLTAwMDAtMDAwMDAwMDAwMDAwIn0.AAAAAAAAAAAAAAAAAAAAAAAA — JWT access token with Entra-like structure
eyJ0eXAiOiJKV1QiLCJhbGciOiJSUzI1NiJ9.eyJpc3MiOiJodHRwczovL2xvZ2luLm1pY3Jvc29mdG9ubGluZS5jb20ifQ.BBBBBBBBBBBBBBBBBBBBBBBB — JWT with Microsoft login issuer
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ0ZXN0IjoiMDAwMDAwMDAwMDAwMDAwMDAwMDAwMCJ9.CCCCCCCCCCCCCCCCCCCCCCCC — JWT access token with test payload

Should not match

eyJhbGci — Truncated JWT header, not a complete token
This is not a JWT token — Plain text, not a token
template example placeholder record identifier — Template/sample context should be excluded even when anchor words are present

Known false positives

JWT tokens from non-Microsoft identity providers that share the same format. Mitigation: Check for Microsoft Entra specific claims (iss, aud) or corroborative keywords.
Expired or revoked access tokens in logs and audit trails. Mitigation: Flag for review since the token structure may reveal tenant and application details.

References

Microsoft Entra client access token entity definition - Microsoft Learn