This module uses a path confusion that leads to an authentication bypass (ACL) which allows unauthenticated access to an arbitrary backend URL. Then an elevation of privilege present in CommonAccessTokenFromUrl of RemotePowershellBackendCmdletProxyModule.cs is used to execute Exchange powershell commands as Exchange Administrator. Finally, an arbitrary file write present in the New-MailboxExportRequest Exchange powershell command is used to write a webshell in the system file. The deployed agent will run with the SYSTEM privileges.
A vulnerability in the admin web interface could allow an authenticated attacker to upload a custom template to perform an arbitrary code execution. These templates can be used to display customised login and meeting pages and are rendered using the Perl Template Toolkit engine. This engine can be coerced into executing code by creating a new "BLOCK" by abusing the "template" global object to create a new block to be evaluated. The deployed agent will run with ROOT privileges.
This module first exploits a server side request forgery vulnerability present in Microsoft.Exchange.HttpProxy of Microsoft Exchange Server to bypass authentication. Then an arbitrary file write vulnerability present in WriteFileActivity of Microsoft.Exchange.Management.ControlPanel.DIService is used to deploy a .aspx file and execute commands. The deployed agent will run with the SYSTEM privileges.