Proxy-Raser is malware intended to serve as a proxy on the victim machine.

These proxy Trojans act as a middleman between a requesting system and a destination host. They are designed to listen on a specified TCP port for incoming requests. Those requests are then sent out from the infected system to the desired destination. The response from the destination server is rerouted back to the originating host by the proxy Trojan.

This proxy allows for a Trojan author/distributor to use the infected system as a type of identity shield, allowing them to navigate to different locations on the Internet without divulging who or where they really are.

Such proxies can be used to surf the web anonymously, hack systems, or relay spam.

More information can be found at this Sophos page.