4.7 File Permissions

Improper file permissions can be the source of several vulnerabilities. File permissions determine not only what the user has access to but also what programs that user can run. Additionally, since some programs will run under the context of a higher-level user, misconfiguration on these programs might allow a user to elevate his or her access. Sometimes directories are made world writable or give full control to the “everyone” group, leaving hackers with an open door into the systems. You should regularly review file permissions and set them at the most restrictive level possible while still achieving the desired result of the sharing operation.