1 00:00:00,000 --> 00:00:01,170 Today, we're going to go over 2 00:00:01,170 --> 00:00:03,480 Assuming Superuser Privileges. 3 00:00:03,480 --> 00:00:06,300 Now, in IT security it's best practice 4 00:00:06,300 --> 00:00:08,790 to give users the least amount of privilege. 5 00:00:08,790 --> 00:00:13,263 With Linux the root administrator has ultimate power. 6 00:00:14,190 --> 00:00:16,860 It can execute any function on any file. 7 00:00:16,860 --> 00:00:19,200 Now, that's not best practice. 8 00:00:19,200 --> 00:00:22,830 So, the best thing to do whenever you log on to any system, 9 00:00:22,830 --> 00:00:25,140 is log into a standard user account, 10 00:00:25,140 --> 00:00:28,020 and then elevate your privileges as necessary. 11 00:00:28,020 --> 00:00:30,600 Now, one great way of accomplishing this, 12 00:00:30,600 --> 00:00:32,369 is using the pseudo command. 13 00:00:32,369 --> 00:00:35,070 Being root should be used sparingly, 14 00:00:35,070 --> 00:00:38,700 because again, anything you type can be executed. 15 00:00:38,700 --> 00:00:39,870 And there's some functions 16 00:00:39,870 --> 00:00:41,610 and there's some commands that you can do, 17 00:00:41,610 --> 00:00:44,460 to create inadvertent causes to the systems, 18 00:00:44,460 --> 00:00:47,430 that could be devastating and irreversible. 19 00:00:47,430 --> 00:00:48,840 So we want to make sure that we're using 20 00:00:48,840 --> 00:00:51,510 these commands very sparingly, 21 00:00:51,510 --> 00:00:52,560 and with forethought. 22 00:00:53,400 --> 00:00:54,233 All right. 23 00:00:54,233 --> 00:00:55,066 First things first. 24 00:00:55,066 --> 00:00:57,273 We're going to log in as a root user. 25 00:00:58,800 --> 00:01:00,600 Going to prompt us for a password here. 26 00:01:02,970 --> 00:01:07,080 And now we're executing as the root privileged user. 27 00:01:07,080 --> 00:01:09,270 Now, another way of doing this, 28 00:01:09,270 --> 00:01:11,910 if you want to exit out of here, log out. 29 00:01:11,910 --> 00:01:16,910 Is to just do su - without any options after the dash. 30 00:01:18,090 --> 00:01:19,980 It assumes that you want to do root. 31 00:01:19,980 --> 00:01:21,240 So that's just a faster way to do it, 32 00:01:21,240 --> 00:01:22,703 if you want to do it that way. 33 00:01:24,000 --> 00:01:27,420 Now, we're going to use the ID command to verify our privilege. 34 00:01:27,420 --> 00:01:30,330 Now for a super user or a root, 35 00:01:30,330 --> 00:01:33,240 the user ID, UID is always zero. 36 00:01:33,240 --> 00:01:36,420 So that's one quick way to know exactly who you are, 37 00:01:36,420 --> 00:01:38,760 if you're going to use this ID command. 38 00:01:38,760 --> 00:01:39,593 I want to make sure, 39 00:01:39,593 --> 00:01:41,190 we're going to check our present working directory. 40 00:01:41,190 --> 00:01:42,023 All right. 41 00:01:42,023 --> 00:01:43,410 Typically once you switch to user 42 00:01:43,410 --> 00:01:45,930 you're executing out of the root directory. 43 00:01:45,930 --> 00:01:47,733 So, something to keep note of. 44 00:01:48,570 --> 00:01:52,080 Now, the pseudo files allows us to 45 00:01:52,080 --> 00:01:55,920 tailor the type of privileges an account can have. 46 00:01:55,920 --> 00:01:58,470 Typically you can use Vim or Nano 47 00:01:58,470 --> 00:02:00,150 for any type of text editing. 48 00:02:00,150 --> 00:02:02,280 But specifically for sudoers, 49 00:02:02,280 --> 00:02:04,020 just to make sure there's no errors, 50 00:02:04,020 --> 00:02:06,963 you can only use the Visudo. 51 00:02:08,789 --> 00:02:12,480 So, we're going to use testadmin in this example. 52 00:02:12,480 --> 00:02:14,543 So we're going to switch to him really quick. 53 00:02:19,008 --> 00:02:20,850 Now we're going to try to run this command 54 00:02:20,850 --> 00:02:22,083 the shut down command, 55 00:02:24,630 --> 00:02:26,830 just to see the effects of the sudoers file. 56 00:02:27,810 --> 00:02:28,643 Try to reboot, 57 00:02:28,643 --> 00:02:31,233 that's what the -r stands for, in 15 minutes. 58 00:02:36,300 --> 00:02:37,133 Now we see the output, 59 00:02:37,133 --> 00:02:40,470 it says the "testadmin is not in the sudoers file. 60 00:02:40,470 --> 00:02:42,420 This incident will be reported." 61 00:02:42,420 --> 00:02:45,600 So that means this user does not have the correct privileges 62 00:02:45,600 --> 00:02:47,820 to execute this to command. 63 00:02:47,820 --> 00:02:49,833 So what we're going to do is modify this. 64 00:02:52,890 --> 00:02:54,440 We're going to switch to the root. 65 00:02:58,170 --> 00:02:59,470 And now let's use the 66 00:03:01,063 --> 00:03:01,896 Visudo. 67 00:03:01,896 --> 00:03:05,580 This gets us into the sudoers file so we can edit it. 68 00:03:05,580 --> 00:03:06,780 We can go to the bottom, 69 00:03:11,010 --> 00:03:13,890 and use the end key. 70 00:03:13,890 --> 00:03:15,510 It's at the end of the line. 71 00:03:15,510 --> 00:03:17,313 And now we're going to go use O, 72 00:03:18,150 --> 00:03:20,100 to start the insertion. 73 00:03:20,100 --> 00:03:20,950 We use testadmin. 74 00:03:23,550 --> 00:03:24,480 And we're going to allow, 75 00:03:24,480 --> 00:03:26,193 that's what this ALL stands for, 76 00:03:27,450 --> 00:03:30,063 all provisions. 77 00:03:31,230 --> 00:03:32,430 And just for convenience, 78 00:03:32,430 --> 00:03:34,200 we're going to add the NOPASSWD. 79 00:03:34,200 --> 00:03:37,470 Cause typically every time you use the sudo command 80 00:03:37,470 --> 00:03:41,130 it requires you to enter your password. 81 00:03:41,130 --> 00:03:42,750 This is not recommended, 82 00:03:42,750 --> 00:03:45,690 but for the sake of this example 83 00:03:45,690 --> 00:03:47,730 it makes things a lot easier, 84 00:03:47,730 --> 00:03:49,050 or more efficient. 85 00:03:49,050 --> 00:03:51,033 But for security it's a no go. 86 00:03:53,010 --> 00:03:54,303 Okay here. 87 00:03:56,850 --> 00:03:57,933 Right, quit. 88 00:04:00,210 --> 00:04:02,943 Now let's switch it back to at testadmin again, 89 00:04:05,490 --> 00:04:07,133 and let's try to run that command. 90 00:04:13,986 --> 00:04:16,736 And this is reboot in 15 minutes. 91 00:04:17,850 --> 00:04:21,329 Now we see we're able to successfully execute that command. 92 00:04:21,329 --> 00:04:23,460 So the sudoer file again, 93 00:04:23,460 --> 00:04:26,100 allows us to add users to their file. 94 00:04:26,100 --> 00:04:27,300 So the system knows, 95 00:04:27,300 --> 00:04:29,853 hey they can perform root level privileges. 96 00:04:31,350 --> 00:04:33,420 And of course you can tailor which privileges 97 00:04:33,420 --> 00:04:34,740 and which commands to be executed. 98 00:04:34,740 --> 00:04:37,893 But for the example we just set it to all privileges. 99 00:04:40,170 --> 00:04:41,820 All right, I'll exit out of this. 100 00:04:42,720 --> 00:04:46,293 And so now we want to actually cancel this reboot, 101 00:04:49,440 --> 00:04:50,273 c. 102 00:04:51,570 --> 00:04:53,470 So now that was successfully canceled.