November 24, 2018

The Risks of a Free Proxy Server

There are many uses for a proxy server, but a lot of people don’t see a reason to pay for one. Lots of free ones are available out there, so why not just pick one and use it? You can do that, but you’ll run into other kinds of costs besides money. Their performance may be less than thrilling, and not all of them are trustworthy.

Whether a free proxy is all you need depends on what you want to do with it.

  • You might want to hide your IP address from a particular site. You need anonymity, or they’ve blacklisted your address.
  • Local authorities might be keeping everyone in your area from visiting some sites. Using a proxy outside their reach will let you through.
  • Sites or pages may have geographic restrictions on who can access them. This is especially common with licensed video. Using a proxy in the destination country gets around those restrictions.
  • Your local network, such as the place where you work, might not let you visit sites which you really need to access. The limitations might get in the way of your doing your job properly.
  • You may be testing what happens when you access a site from a foreign location. In this case, multiple proxies in different geographic areas could be helpful.
  • You may want to do something illegal and harmful and not get caught. Please go somewhere else if that’s your purpose.

If you’re just looking for a one-time proxy to deal with a problem or try something out, paying may seem excessive. If you’re careful, you can find a free one that will serve your purpose. If you have ongoing needs, you’ll want something better. Let’s look at the reasons.

The World of Free Proxies

There are millions of free proxy servers in the world that are open to anyone and don’t charge anything. They’re a very mixed bag. You never know when new ones will appear or existing ones will disappear.

Not all of them provide the same level of anonymity. There are three major categories, defined by how well they hide your identity:

  • Caching proxy. It forwards all IP address information to the destination and makes no attempt at privacy. As the name implies, their purpose is to cache data and reduce access to destination servers. They normally reside within a private network. You aren’t likely to find a public free caching server.
  • Anonymous proxy. It doesn’t convey your IP address to the destination, but its headers identify it as a proxy. This functions as a disclaimer of responsibility; the proxy is just conveying requests, not originating them. Most free proxies are this type.
  • Elite proxy. This type of proxy tries to look like a client device. Some destination servers block proxies, and an elite server has a better chance of getting through. Its traffic patterns can still reveal that it’s a proxy.

Generally, these proxies use the SOCKS protocol and can handle any kind of traffic. Some are specific to one TCP protocol, usually HTTP. Another category is the web-based proxy. Rather than configuring the proxy settings for your browser, you go to a website and give it a URL to access.

Whichever type of proxy you use, its performance, reliability, and honesty are major factors to consider. One which has slow throughput and is often down isn’t worth a lot. One which intercepts or falsifies data can be an outright liability. If it delivers malware, that’s even worse.

Why do people run free proxies? Some do it as a hobby. Some are pursuing an ideal, such as uncensored Internet access. The majority do it at least partly for the revenue. Most free proxies are ad-supported. Computing power is cheap but bandwidth isn’t, and a proxy server needs lots of bandwidth. The money has to come from somewhere, whatever the motive for running it is.

Some providers offer both free and paid options. They hope that some of their users will like the service but won’t be satisfied with the speed or ads at the free level. The free proxy is a way to generate paying customers.

And then there are some who run free proxies for criminal motives. They redirect links, steal passwords, or inject malware. The criminals often don’t use their own machines but infect victims with proxy servers which they control. The ProxyBack malware does this, and Palo Alto Networks reported that some of its users were “legitimate, benign users” who presumably were duped by the offer of a free proxy.

At a Black Hat conference, a security consultant explained how he set up an anonymous proxy server and advertised its address. Within a day, it had placed JavaScript spyware on more than 4,000 computers that visited the site.

Free Proxies with Registration

Not all free proxies are wide open. Many of the more reputable services require registration. This discourages illegal activity and other forms of abuse. Users have to provide at least an email address, which the service will verify. Registration to a free proxy reduces your anonymity a little since all your traffic is associated with the same account.

On the positive side, a registration process is a sign that the service has a commitment to staying around and keeping abusers out. A proxy service that has been around a while, gets good reviews, and requires registration is far less likely to do nasty things than one picked at random from a list of free servers.

Security Risks


You’ve heard of a man-in-the-middle attack? A proxy server is a man in the middle by design. As such, it’s capable of doing all kinds of things to the traffic that passes through it. Any proxy that doesn’t have a strong reputation for respecting its users’ privacy could be grabbing or changing data.

One analysis found that 20.6% of a set of 13,307 proxies modified the JavaScript and 17.9% modified the HTML of traffic going through them. This might have been for relatively harmless purposes such as injecting advertising, but it could also have been for malicious goals.

If you use a secure HTTPS connection, you’re safe from most of these risks. The proxy can see the domain or IP address of the destination server, but not the content. Even then, a proxy can sometimes downgrade a connection to an unencrypted one without being noticed.

The analysis just mentioned found that a whopping 62.3% of the proxies banned HTTPS traffic. This is alarming. The only reason to ban HTTPS is to be able to spy on all the packets coming through.

A proxy can inject content. As already mentioned, free ones may inject ads. That’s considered legitimate, as long as the proxy says that it does that, but it could also make sneakier additions. For instance, it could add malicious JavaScript or redirect links.

All cookies that come over an unsecured connection are available to the proxy. It can use them for session hijacking or examine them for personal data. It can alter their content or add its own cookies. These changes could even change the identity of the user that the destination sees.

Many proxies log their transactions. This is legitimate as such, but it can compromise anonymity. Even if you use HTTPS, the proxy knows what sites you visit. It might use the information for blackmail or turn it over to the Internet police in an authoritarian state.

Performance and Reliability Issues

In the best case, a proxy can speed up performance. It caches data from the destination and delivers it faster. A free proxy, though, will slow down performance compared to a direct connection. It has to retransmit data in both directions. A typical free proxy handles a lot of connections on a tight budget. It doesn’t have a lot of incentive to invest in bandwidth.

Sites that offer both free and paid services usually cap the free version’s data speed. They don’t want it to consume too much of their resources, and they want to offer a reason to pay. Most users won’t even get the full capped speed.

Some proxies belong to well-established businesses and are going to stay around for a while. Others might be around for just a day or a week and then disappear. The ones that advertise themselves only by IP address are especially prone to disappearing without warning. Those that don’t disappear may be down a lot of the time, leaving you to wonder if they’ll come back.

A server’s own security is another unknown. Even if the owner doesn’t intend anything nefarious, a proxy server is an attractive target for infecting. People who set one up aren’t always very good at keeping malware off it.

Other Issues

Most free proxies rely on advertising. This can be in the form of a separate ad page when you connect, which isn’t too bad. It could also take the form of injecting ads into a page, replacing or adding to existing ones. These ads give the impression of having been vetted by the site they appear on, but they haven’t been. The ads could even constitute “malvertising,” content designed to introduce malicious JavaScript to a trusted page. The proxy owner isn’t being malicious but hasn’t screened the advertisers carefully enough.

When you go through a proxy, you’re sharing an IP address with a lot of other people who are trying to hide their identities. If the server lets anyone use it without enforcing an acceptable use policy, a lot of sites are going to block it. You’ll keep finding that you can’t view the sites you want.

The server’s location can be an issue. It’s useful to have a proxy in a known location if you want to test access from there. If you pick an arbitrary proxy, though, it could be located anywhere in the world. You might see pages localized strangely. They might come up in a language you don’t know.

The Tor Network

A discussion of free proxy servers can’t ignore the Tor network. It’s more like a VPN than a proxy, but it’s free and it serves the same purposes. It has many of the same advantages and disadvantages.

You need a special browser to access the network. It encrypts all your data and then routes it through several nodes. The packets are decrypted only when they reach an exit node. Because of the multiple routing, it doesn’t know where the data came from. To the destination server, data packets appear to come from the exit node.

To ensure anonymity, Tor disables several Web features that can leak user information, such as Flash and QuickTime. This protects users but makes some sites unusable.

Tor’s reputation is very good. It does a good job at hiding a user’s identity and location, and its design limits the damage any rogue node can do. Regular updates of its browser provide a high level of security.

Still, it shares a number of problems with traditional proxy servers. Traffic through the network can be very slow. Some sites block Tor exit nodes or limit the functionality they’re allowed. An exit node can be located anywhere, producing unexpected localizations. Many people use Tor regularly, but they have to accept its limitations.

Paid or Free Proxy?


Free proxy servers won’t give the best performance, but they’re a reasonable choice for occasional use. It’s important to research a proxy’s reputation before using it, rather than picking the first one in a list. Performance will be an issue, but a slow speed may be acceptable if you don’t need the proxy very often. Under those circumstances, a trustworthy free service can be adequate and reasonably safe.

In other cases, you’ll need something more. You might be a journalist who travels to places where your profession is dangerous. You might be a researcher who wants to see how access from different geographical locations works. You might just need to get around overly restrictive network limitations to do your job properly. If it’s a regular need, you’ll want something better and should consider putting a little money into it.

Free or paid, you still need to research your choice. If you’re going to spend money, it should be on a trustworthy server that offers good performance. It should give you a choice of locations or at least satisfy your localization needs.

If you use it just once in a while, a reputable free proxy is OK. For ongoing use, a paid proxy — again, one with a good reputation — will deliver better performance, be more reliable, and not annoy you with ads.