7.3 Set Default umask for users - UMASK = 027

Information

The default umask(1) determines the permissions of files created by users. The user creating the file has the discretion of making their files and directories readable by others via the chmod(1) command. Users who wish to allow their files and directories to be readable by others by default may choose a different default umask by inserting the umask command into the standard shell configuration files (.profile, .cshrc, etc.) in their home directories.

Setting a very secure default value for umask ensures that users make a conscious choice about their file permissions. A default umask setting of 077 causes files and directories created by users to not be readable by any other user on the system. A umask of 027 would allow files and directories readable by users in the same Unix group, while a umask of 022 would make files readable by every user on the system.

Solution

Perform the following to implement the recommended state:
# cd /etc/default
# awk '/#UMASK=/ { $1 = "UMASK=027" } { print }' login > login.CIS
# mv login.CIS login

See Also

https://workbench.cisecurity.org/files/612

Item Details

Category: ACCESS CONTROL

References: 800-53|AC-3(4)(d)

Plugin: Unix

Control ID: b2a64ba9eac16f33464ea9b36c946abbcbd279d25efd89c149bc8b81ead003dd