A proxy server, by definition, is a network service that allows clients to make indirect network connections to other network services like the Internet, giving users the freedom of browsing the Web.

The use of certain Firewall/Web filtering applications by some corporations, organizations, universities or countries shows that each is willing to spend a lot of money on Internet censorship to block malicious Web sites or others that are not related or appropriate to its business needs (e.g. porn sites).

However, there exist software on the Web today that claim to be able to bypass firewall rules and Web filtering application policies. These tools, namely Freegate, GPass, GTunnel and UltraSurf, may seem attractive as they enable one configured browser to access Web sites like Facebook, MySpace, YouTube, etc. even if the said sites are currently being blocked by firewall or Web filters (for instance, in office workstations). However, as with any unendorsed software freely available over the Internet, using these tools open the affected network to possible attack.

Trend Micro recently detected one of these proxy surfing tools (UltraSurf) as HKTL_PROXSURF.A using spyware pattern file version TMAPTN 576.34. These tools only need a Firefox browser and a plugin proxy toolbar that enables a user to switch to a different proxy surfing tool.

The following are screenshots of the said utilities in action:

In any case, freedom of Web browsing should always be controlled by restriction and limitation within the organization’s internal policies to prevent threats that are always available on the World Wide Web.