You're correct: Installing monitoring software on the client system (Computer A in your example) is the easiest way to gather all of the information the attacker is seeking. However, there are several other ways this sort of information collection could take place. First, it would be possible to gather the same information by installing monitoring software on both of the servers. Second, the same information could be gathered by sniffing the network connection. Is the network between the client and servers entirely under your control? All of the network devices between the systems should also be considered as possible eavesdropping points.
How can these attacks be prevented? Protecting against monitoring software is a function of endpoint security: Be sure you know what devices are present on your network and that you carefully control the software that is installed on them. You can protect against network-based eavesdropping attacks by using encryption. For example, if the connection between the client and server is Web-based, use HTTPS-encrypted connections to prevent an eavesdropper from reading the content of the communication.
For more information:
- Should software be used to monitor networks for blogging activity? Read more.
- Learn how to prevent eavesdropping on mobile devices in this expert response.
This was first published in August 2009