CompTIA Security_ Deluxe Study Guide_ SY0-201 - Emmett Dulaney [277]
All workstations should require authentication after a time of nonuse. One of the easiest ways to protect a workstation is to use a screensaver that requires a password to exit:
1. From the desktop, choose System Personal Settings Shortcuts.
2. Click the action titled Lock Screen.
3. Enter the keyboard combination for this action (the default is Alt+F12).
4. Click Close.
5. Exit the Settings dialog box and verify that the screensaver works when you press the key combination.
Lab B.9: Change a Password in Linux
This lab requires a Linux workstation.
A user can change their password at any time (unless you have locked this ability) and should be encouraged to do so if they feel their password might have become compromised. Here are the steps a user would follow to change their own password:
1. From the desktop, choose Programs Accessories Terminal.
Your menu choices might differ slightly based upon the Linux distribution you are using.
2. At the prompt, type passwd.
3. Enter the old password at the prompt.
4. Enter what you want the password to now be at the next prompt. If the value given does not meet the requirements configured for the system (password length, mix of alphanumeric characters, and so forth), it will not be accepted.
5. At the next prompt, enter the new value again. This value must match what was typed in before or the password will not be changed.
6. When the message appears stating that the password has been changed, exit the terminal window.
Lab B.10: Find SUID and SGID Files in Linux
This lab requires a Linux workstation.
In addition to standard permissions, Linux contains two special permissions that can pose security risks. The first permission, SUID, makes anyone running the file the user that created the file, so if root created the file, the user running it becomes root during its execution. The second permission, SGID, makes anyone running the file a temporary member of the group associated with the file.
Because these permissions are so powerful, you need to routinely monitor the files in which they are set. To file all SUID and SGID files on the system, follow these steps:
1. From the desktop, choose Programs Accessories Terminal.
Your menu choices might differ slightly based upon the Linux distribution you are using.
2. At the prompt, type su to become the root user (you can also use sudo). Enter the appropriate password at the prompt.
3. Type the command find / -perm -2000 -print | more.
4. Study the list and make certain you can explain every file that appears as being a system file or other special utility.
5. When you are finished, exit the terminal window.
Lab B.11: Change ACLs on All Files in a Linux Directory
This lab requires a Linux workstation.
Two utilities exist in Linux to allow you to work directly with the access control lists (ACLs) for files: getfacl, which shows the ACL information, and setfacl, which allows you to set the ACL information.
Using these two together, you can take the ACLs from one file and make them apply to others. In this lab, you’ll take the ACLs from the .fonts.cache-1 file (beneath /root) and make it apply to all files in the /tmp directory. To do so, follow these steps:
1. From the desktop, choose Programs Accessories Terminal.
Your menu choices might differ slightly based upon the Linux distribution you are using.
2. At the prompt, type su to become the root user. Enter the appropriate password at the prompt.
3. Type the command cd /tmp.
4. Type the command getfacl /root/fonts.cache-1 | setfacl -set-file=- *.
5. When you are finished, exit the terminal window.
Lab B.12: Change Permissions on All Files in a Linux Directory
This lab requires a Linux workstation.
You can use the chmod utility to change the permissions on one or many files. This exercise changes the permissions on all files beneath the /tmp directory to readonly for everyone (r--r--r--).
To accomplish this change, follow these steps:
1. From the desktop, choose Programs Accessories Terminal.
Your menu