June 6, 2016 By Larry Loeb 2 min read

Network file system (NFS) is a computer protocol that describes how to connect and access files via a network connection. It is used to store and share data, but early versions of the protocol do not provide or request user-based authentication.

Since the fourth version, NFS has been using Kerberos to improve authentication. Unfortunately, this version has not been widely implemented, leaving some holes that are catching the attention of experts — and cybercriminals.

NFS Servers Leak Data Like a Sieve

Security research firm Fortinet recently took a look at NFS, and its conclusions are rather worrisome. It found that “most servers on the Internet that have been linked to data leakage have been shown to use NFSv3.”

Fortinet used data from the website Shodan and found that 10 percent of NFS servers in the world are open for everyone to access with no need for a password. Some of these servers contained confidential data such as email backups, server logs and web source code.

This isn’t limited to just read-only access, either; Fortinet found that write access is often available as well.

Thousands of the exposed servers were located in the U.S. (18,843 servers), China (11,608), France (10,744), Germany (7,188) and Russia (5,269), the firm reported.

Mitigating the Risk

Fixing this problem can be a bit tricky. Fortinet strongly recommended upgrading NFS to version 4, but this isn’t possible for every organization.

If one of the earlier versions of NFS must be used, then there should be a specific white list of allowed IP addresses that can access the data. While the security firm noted that “this process can be tedious and time consuming,” it is a critical part of establishing “data security protocols that will prevent sensitive or confidential data from being accessible from the internet.”

Enabling the NFS application control signature on a system’s main gateway can also block all unexpected NFS connections from the outside to prevent data leakage.

Correct NFS configuration can be a pain for the system administrator, but saving a server from exploitation by cybercriminals will be worth it.

More from

What does resilience in the cyber world look like in 2025 and beyond?

6 min read -  Back in 2021, we ran a series called “A Journey in Organizational Resilience.” These issues of this series remain applicable today and, in many cases, are more important than ever, given the rapid changes of the last few years. But the term "resilience" can be difficult to define, and when we define it, we may limit its scope, missing the big picture.In the age of generative artificial intelligence (gen AI), the prevalence of breach data from infostealers and the near-constant…

Airplane cybersecurity: Past, present, future

4 min read - With most aviation processes now digitized, airlines and the aviation industry as a whole must prioritize cybersecurity. If a cyber criminal launches an attack that affects a system involved in aviation — either an airline’s system or a third-party vendor — the entire process, from safety to passenger comfort, may be impacted.To improve security in the aviation industry, the FAA recently proposed new rules to tighten cybersecurity on airplanes. These rules would “protect the equipment, systems and networks of transport…

Protecting your digital assets from non-human identity attacks

4 min read - Untethered data accessibility and workflow automation are now foundational elements of most digital infrastructures. With the right applications and protocols in place, businesses no longer need to feel restricted by their lack of manpower or technical capabilities — machines are now filling those gaps.The use of non-human identities (NHIs) to power business-critical applications — especially those used in cloud computing environments or when facilitating service-to-service connections — has opened the doors for seamless operational efficiency. Unfortunately, these doors aren’t the…

Topic updates

Get email updates and stay ahead of the latest threats to the security landscape, thought leadership and research.
Subscribe today