Permissions of /Users keep changing back to drwxrwxrwx I use the Disk Utility to repair it. But the permissions change back after reboot.


  Permissions differ on “private/etc/aliases”; should be lrwxr-xr-x ;
  they are -rwxr-xr-x . 
  Permissions differ on “Users”; should be drwxr-xr-x ; they are drwxrwxrwx . 
  Permissions differ on “Users/Shared”; should be drwxrwxrwt ; they are drwxrwxrwx .


System: Mac OS X 10.9.3
This problem was caused by a bug introduced by an Apple software update. iTunes 11.2.1 has been released to fix the issue.


  iTunes 11.2.1
  
  Impact: A local user can compromise other local user accounts
  
  Description: Upon each reboot, the permissions for the /Users and /Users/Shared directories would be set to world-writable, allowing modification of these directories. This issue was addressed with improved permission handling.


This vulnerability was assigned the security identifier CVE-2014-1347.