This article has multiple issues. Please help improve it or discuss these issues on the talk page. (Learn how and when to remove these messages) This article relies largely or entirely on a single source. Relevant discussion may be found on the talk page. Please help improve this article by introducing citations to additional sources. Find sources: "Unix security" – news · newspapers · books · scholar · JSTOR (April 2024) This article includes a list of general references, but it lacks sufficient corresponding inline citations. Please help to improve this article by introducing more precise citations. (April 2024) (Learn how and when to remove this message) (Learn how and when to remove this message)

Unix security refers to the means of securing a Unix or Unix-like operating system.

A core security feature in these systems is the file system permissions. All files in a typical Unix filesystem have permissions set enabling different access to a file. Unix permissions permit different users access to a file with different privilege (e.g., reading, writing, execution). Like users, different user groups have different permissions on a file.^{[citation needed]}

Many Unix implementations add an additional layer of security by requiring that a user be a member of the wheel user privileges group in order to access the su command.^{[1][obsolete source]}

Most Unix and Unix-like systems have an account or user group which enables a user to exact complete control over the system, often known as a root account. If access to this account is gained by an unwanted user, this results in a complete breach of the system. A root account however is necessary for administrative purposes, and for the above security reasons the root account is seldom used for day to day purposes (the sudo program is more commonly used), so usage of the root account can be more closely monitored. ^{[citation needed]}

On many UNIX systems, user and password information, if stored locally, can be found in the /etc/passwd and /etc/shadow file pair.^{[citation needed]}

There are viruses and worms that target Unix-like operating systems. In fact, the first computer worm—the Morris worm—targeted Unix systems.

There are virus scanners for UNIX-like systems, from multiple vendors.

• List of Unix systems

• Practical UNIX and Internet Security, Simson Garfinkel and Gene Spafford, O'Reilly & Associates, 2003.