Open a terminal emulator, navigate to /system/xbin with the "cd" command, and type "chmod 755 whateverthefileis". That'll change the permissions. If you want an explanation of what you're actually doing, you can read below. It's not necessary if you're not interested though.
If you're curious:
I guess I'll attempt briefly explaining the chmod command and Linux (Unix, Android, etc) permission notation. What do you want the file's permissions to be? In Linux, a file has an owner (who is the most intimately tied to the file), a group (which allows you to assign fewer privileges than the owner, but more control than default) and other (which means anyone not specified by the previous 2 conditions). For each of these groups, you can assign read, write, and execute permissions. These are written as rwx triplets. The notation "rwx" means full read, write, and execute permissions to whatever category of user that triplet is referring to. If you want to deny one of those permissions, replace the letter by the "-" placeholder. So "r-x" would mean that category of users wouldn't have write permissions. Files have these permissions listed in rwx triplets for the owner first, then the group, then others and are lead by what will usually be an initial "-" placeholder. So a file with permissions listed as "-rwxrw-r--" has an initial "-" placeholder like usual, followed by full rwx permissions for the owner, read and write permissions for the group, and read permissions for everyone else. You can view the permissions of any file by opening a terminal emulator, navigating to the directory where it is located and typing "ls -l" which will list details about each file in the directory, including permissions.
The chmod command in the form that was mentioned above, condenses the triplet describing the permissions for each group into a single number. It does this by treating permissible operations in each triplet as a 1, and operations that are denied as a 0. So if the owner's permissions are described as "rw-", this would translate into "110". This number is then read as binary and converted to decimal. 110 in binary equals 6 in decimal. So what "chmod 755 whateverfile" means is change the permissions of whateverfile to allow the owner full rwx permissions, allow members of the group the file belongs to read and execute permissions. And allow everyone else read and execute permissions as well. So "755" means "111|101|101" if you expand those back to the binary. And if we replace each 1 with the number it is representing, it will look like "rwxr-xr-x".