In computer programming and computer security, privilege separation is one software-based technique for implementing the principle of least privilege. With privilege separation, a program is divided into parts which are limited to the specific privileges they require in order to perform a specific task. This is used to mitigate the potential damage of a computer security vulnerability.
A common method to implement privilege separation is to have a computer program
fork into two
processes. The main program drops
privileges, and the smaller program keeps privileges in order to perform a certain task. The two halves then communicate via a
socket pair. Thus, any successful attack against the larger program will gain minimal access, even though the pair of programs will be capable of performing privileged operations.
Privilege separation is traditionally accomplished by distinguishing a real
. If these are incorrectly positioned, gaps can allow widespread network penetration.
Many
run-time as well. Such software tends to separate privileges by revoking them completely after the critical section is done, and change the user it runs under to some unprivileged account after so doing. This action is known as
dropping root under
Unix-like operating systems. The unprivileged part is usually run under the "
nobody" user or an equivalent separate user account.
Privilege separation can also be done by splitting functionality of a single program into multiple smaller programs, and then assigning the extended privileges to particular parts using
file system permissions. That way the different programs have to communicate with each other through the operating system, so the scope of the potential vulnerabilities is limited (since a
crash in the less privileged part cannot be
exploited to gain privileges, merely to cause a
denial-of-service attack).
Separation of privileges is one of the major
.
See also
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