Outlook Web Access (OWA) has been one of the consistently viable attack vectors for pentesters and bad guys alike for many years. Frequently, an attacker will obtain valid credentials by brute forcing OWA portals exposed to the internet. Once credentials are obtained an attacker can then access the target network via any other single factor authentication portals that may also be exposed (Citrix, VPN, or *gulp* RDP).

After using multiple brute force tools I began to see some false negatives, so I decided to dive into writing my own tool. I found that many installations of Exchange provide an API through the Exchange Web Service (EWS) and wrote a set of modules to take advantage of that.

The EWS is a convenient API exposed to allow programatic access to someones mailbox and some Exchange functionality (Thanks Microsoft!). To get started using these modules you have to install the Exchange Web Service API (here). Once that is installed get a copy of the OWA-Toolkit from here. Then import the module like so: