{"id":"53bb4f7f-48a8-4475-ac30-5a82ddfdf6fc","title":"Potential MFA Bypass Using Legacy Client Authentication","description":"Detects successful authentication from potential clients using legacy authentication via user agent strings. This could be a sign of MFA bypass using a password spray attack.","author":"Harjot Singh, '@cyb3rjy0t'","status":"test","level":"high","date":"2023-03-20","modified":"","tags":["attack.privilege-escalation","attack.persistence","attack.initial-access","attack.credential-access","attack.stealth","attack.t1078.004","attack.t1110"],"technique_ids":["T1078.004","T1110"],"logsource":{"product":"azure","service":"signinlogs"},"falsepositives":["Known Legacy Accounts"],"references":["https://web.archive.org/web/20230217071802/https://blooteem.com/march-2022","https://www.microsoft.com/en-us/security/blog/2021/10/26/protect-your-business-from-password-sprays-with-microsoft-dart-recommendations/"],"source_path":"rules/cloud/azure/signin_logs/azure_ad_suspicious_signin_bypassing_mfa.yml","source_sha256":"ddb6668f7a6b2c5549c163d98efc020aa981b2ad058d2def4cba9d338438d09f","source_url":"https://github.com/anpa1200/sigma/blob/b249e9683190cffdcaf188ccbfb90bf4759844e1/rules/cloud/azure/signin_logs/azure_ad_suspicious_signin_bypassing_mfa.yml","license":"Detection Rule License 1.1","license_url":"https://github.com/SigmaHQ/Detection-Rule-License/blob/main/LICENSE.Detection.Rules.md","yaml":"title: Potential MFA Bypass Using Legacy Client Authentication\nid: 53bb4f7f-48a8-4475-ac30-5a82ddfdf6fc\nstatus: test\ndescription: Detects successful authentication from potential clients using legacy authentication via user agent strings. This could be a sign of MFA bypass using a password spray attack.\nreferences:\n    - https://web.archive.org/web/20230217071802/https://blooteem.com/march-2022\n    - https://www.microsoft.com/en-us/security/blog/2021/10/26/protect-your-business-from-password-sprays-with-microsoft-dart-recommendations/\nauthor: Harjot Singh, '@cyb3rjy0t'\ndate: 2023-03-20\ntags:\n    - attack.privilege-escalation\n    - attack.persistence\n    - attack.initial-access\n    - attack.credential-access\n    - attack.stealth\n    - attack.t1078.004\n    - attack.t1110\nlogsource:\n    product: azure\n    service: signinlogs\ndetection:\n    selection:\n        Status: 'Success'\n        userAgent|contains:\n            - 'BAV2ROPC'\n            - 'CBAinPROD'\n            - 'CBAinTAR'\n    condition: selection\nfalsepositives:\n    - Known Legacy Accounts\nlevel: high\n","validation":"yaml_parsed_not_backend_compiled_or_live_validated","techniques":[{"key":"enterprise/T1078.004","id":"T1078.004","name":"Cloud Accounts","page":"techniques/enterprise/T1078.004/"},{"key":"enterprise/T1110","id":"T1110","name":"Brute Force","page":"techniques/enterprise/T1110/"}],"data_path":"data/detection-rules/53bb4f7f-48a8-4475-ac30-5a82ddfdf6fc.json","kind":"sigma"}