Proxy servers Asia allow users to view unauthorized content, but the proxies themselves and the sites that list them are tricky to detect.
Your concerns are valid about both websites and proxy services which publish lists of available proxy servers. These can be a danger to business security. With these services, employees can bypass firewalls and access and filters unauthorized content — gambling and pornography websites, for example — that are legal liabilities to the enterprise.
External proxy technologies can circumvent company filters which block access to Web-based email and IM. Because both instant messaging and email are vectors for spyware, viruses, malware and other malicious traffic, these websites pose additional risks to the company. And it is not just about what is coming in. The employees can maliciously by avoiding company filters, or send sensitive data outside of the company accidentally.
Proxies allow all unauthorized activities to take place unnoticed. With such services, all that happens on your web logs are connections to the proxy Asia servers that appear as an innocuous external website. The IP address of the inappropriate site or email service provider appears on the proxies’ logs, not yours.
As you correctly notice, the sites which list the proxies are just as much of a threat to the company as the proxies they list. But both of them can be blocked by available web and content filtering tools. Two leading content filter provider are Websense and Blue Coat. Their products can be especially configured to block proxies.
The tools can also block the sites which post lists of available proxies. The filters can be adjusted to detect new websites which may crop up, blocking sites, for example, that might have the word “proxy” embedded in the URL. They both have regular update functions as well.
Another software provider which produces content monitoring tools is Vericept. Like Websense and Blue Coat, Vericept’s products can be adjusted to block proxy websites. Between the 3 products, you should be able to combat malicious proxy server hosting Asia use at your company.
But the proxies themselves and the websites which list them are tricky to detect. They often move around, change their IP addresses or shut down suddenly only to open up shop undetected somewhere else. That may explain some of the issues you are having.