Privilege Escalation
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Video Transcription
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>> Hey, Cybrarians. Welcome back to
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the Linux Plus course here at Cybrary.
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I'm your instructor, Rob Goelz.
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In today's lesson, we're going to
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talk about privilege escalation.
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Upon completion of today's lesson,
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you're going to be able to understand
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the ways you can perform privilege escalation,
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and explain the purpose of privilege escalation groups,
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and how to add users to these groups.
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Although the root user has complete system access,
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it's not recommended to use it
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for system administration work.
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Sharing a root password can be dangerous,
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especially if you're sending around
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between people using plain texts.
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It can easily fall into the wrong hands in
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this type of situation and then
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everyone else would access.
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It's also really difficult to
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audit work done as a root account if everyone's root,
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who knows what's doing what.
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When the account is sure, that's a
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>> very real possibility.
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>> Instead, the general best practice is to
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use a standard user account and then use
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privileged escalation to run
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programs with root privileges temporarily.
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There are three commands that can be
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used to perform privilege escalation.
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They are SU, sudo and sudoedit.
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Now SU, which actually stands for substitute user,
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allows a standard user to run commands as another user.
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Common use case for
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this is to become the root is where you
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could use SU- to become root.
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But you still have to know
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the root password to become root this way.
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Now, another example is
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something that's a little safer is sudo,
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which actually stands for substitute user do.
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This is safer option than SU because it doesn't
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require any user to know the root password.
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A standard user can run a command as
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root by simply providing their password.
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We'll do sudo, the command
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and it'll prompt them for their password.
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If they're in a privilege escalation group,
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they can run sudo and they can
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run that command as if there were root temporarily.
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But as I said, the user account must be in
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a privileged group and we'll talk
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about that in the next slide.
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Now the final privilege escalation
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command you should know about is sudoedit.
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This is really nice if you just need to edit a file,
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but you need privileges to do it,
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you can use sudoedit to temporarily
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become root and edit that file.
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It works the exact same way as sudo.
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You provide the file and you've run sudoedit,
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and then the file or the path of the file,
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it'll prompt you for your own password
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and provide you're in that privileged group,
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you escalate privileges,
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and become root temporarily,
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and you can get in and modify that file.
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Now, users have to be added to
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a privileged group to receive sudo privileges.
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Users can be added to these groups with usermod.
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So usermod ag,
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-a-g, you're going to append the group.
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We saw that before when we were talking about usermod.
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We could add users to sudo or wheel.
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Now wheel is the privileged group
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that is set for Red Hat-based distress.
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If you're going to get sudo privileges in Red Hat,
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nine times out of 10,
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you're going to need to be added to
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the wheel group in order to do that.
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If you're working in Debian-based distros
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like Ubuntu or Linux Mint,
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that privileged group is actually just called sudo.
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You would add a user to that group to have them
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be allowed to do privilege escalation,
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to have them be allowed to use sudo.
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Then additionally, these groups
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sometimes need that they actually be enabled.
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The sudoers file that controls
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which user groups have access or which
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user groups are enabled to be able
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to do sudo is it etc/sudo.
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This is called the sudoers file.
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But it's really not recommend to edit this file
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directly because if you mess up the syntax,
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break things pretty bad.
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The better way to do this, use the VI sudo command,
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that's going to open it into the fault text editor
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that's on the system.
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In Red Hat, that's going to be Vim or VI and Ubuntu.
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Nine times out of 10, that's going to be nano.
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Then you can go in there and make the
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modifications you want to make.
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The system will check the file and
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exit to make sure that the syntax isn't screwed up.
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It won't let you save it if
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there's some problem with the syntax.
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Really, you just have to go in there and
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uncomment the lines for wheel or
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sudo to make sure that those privileged groups
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are enabled and then you can add users to them.
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With that, we've reached the end of this lesson.
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In this lesson, we covered how
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to perform privilege escalation.
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We talked about the purpose of
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privilege escalation groups and
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how to add users to these groups.
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Again, using usermod.
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Thanks so much for being here.
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I look forward to seeing you in the next lesson.
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