Exchange Certificate Request Export to Webserver Path

SigmaHQ Detections@sigmaHQ

•updated Aug 12, 2024•0•21

This rule detects attempts to export an Exchange Certificate Signing Request (CSR) to an unusual directory or with an .aspx file extension. This activity is suspicious because it could indicate an adversary attempting to place a webshell on an Exchange web server for persistent access. The rule specifically looks for the PowerShell cmdlet 'New-ExchangeCertificate' with parameters '-GenerateRequest', '-BinaryEncoded', and '-RequestFile', combined with suspicious file paths like '\\localhost\C$', '\\127.0.0.1\C$', 'C:\inetpub', or the '.aspx' extension.