What Is an Open Proxy?

Proxy servers act as an intermediary between a user’s computer and their server, enabling users to hide their location and access websites that may be blocked by their internet provider. An open proxy is a server configured to allow anyone to use it.

An open proxy server is intentionally made available for general public access and lacks internet security regulations or connection rules. However, many proxy servers that are supposed to be private are often left open due to misconfigured proxy settings.

As a result, open proxy servers are frequently targeted by cyber criminals to identify potential victims and share malware, such as spam and viruses, or illegal content. That is because proxies hide the individual’s Internet Protocol (IP) address from their recipients and treat all incoming connections with the same level of fairness. This means the open proxy server does not check, encrypt, or filter data or content that comes into the server.

Open proxies often sit between two servers or networks and are accessible to all internet users without restriction.

The free access nature of open proxy servers is ideal for anyone who wants to use the internet anonymously and retain the privacy of their personal information. Open proxies are used to run virtual private networks (VPNs), which hide users' IP addresses from public web servers. This makes it harder for cyber criminals to discover users’ identities or intercept their data while browsing the web and other internet services.

Open proxy ports are not restricted by rules and regulations, boosting connection speeds and offering a greater choice of IP addresses. They are also typically free to use and open to anyone who wants to access content, such as streaming media, from another country to avoid regional blocks.

The downside of open proxies treating all incoming connections with equal fairness is that they allow the sharing and transmission of both legitimate and malicious traffic. They also are not policed or monitored as closely as private proxies. As a result, cyber criminals often use open proxies to search for potential victims or deploy automated bots or programs that attack users with spam, viruses, infected kernels, and other malicious attack vectors.

Cyber criminals also use open proxies to link up their botnets and malicious control hubs. This enables them to target vast numbers of users and infect their machines with distributed malware. 

Another disadvantage of open proxies is the wide availability of IP addresses, increasing the chances of a user being tracked and having their data intercepted by malicious actors. This can result in a user’s computer being used as an open proxy without their knowledge. The hacker can then run proxy software or malware on the computer, resulting in misconfiguration or the device being used as a zombie computer as part of a wider botnet.

Furthermore, despite being used by VPNs, open proxies may not deliver true anonymity. Website operators may use client-side scripts to reveal a browser’s actual IP address, and the open proxy may keep logs of all traffic that connects to it.