title: Possible Exploitation of Exchange RCE CVE-2021-42321 author: Florian Roth, @testanull date: 2021/11/18 description: Detects log entries that appear in exploitation attempts against MS Exchange RCE CVE-2021-42321 detection: condition: 'Cmdlet failed. Cmdlet Get-App, ' falsepositives: - Unknown, please report false positives via https://github.com/SigmaHQ/sigma/issues id: c92f1896-d1d2-43c3-92d5-7a5b35c217bb level: critical logsource: product: windows service: msexchange-management references: - https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-42321 status: experimental tags: - attack.lateral_movement - attack.t1210 ruletype: SIGMA