Ubuntu. Accidentally changed ownership of sudo

[Nithin]

I changed owner to normal user. Now I can't do sudo anymore.
Say it needs to be setuid root.

I can't change it back now because sudo won't work.

root account is not enabled.

anything i can do?

N.

 

[bersl2]

Either boot a live CD (perhaps even the install CD might work for this), mount the filesystem with sudo on it, and change the ownership that way, or if you can add init=/bin/bash at the bootloader's command line, then you will bypass everything that normally happens just after the kernel hands control over to userland and be dumped at a root shell; you can then remount the filesystems read/write and change ownership that way.

 

[Nithin]

my first thought was the live cd option. the prob is that its a vmware install. it doesn't see the virtual hdisk when i boot through live cd.
i will try the init option.

[Edit] init= didn't work. i changed the boot line in grub.
but are you sure about it? if this actually worked it would be a huge
security blunder right?

N.

 

[bersl2]

Originally posted by: Nithin
my first thought was the live cd option. the prob is that its a vmware install. it doesn't see the virtual hdisk when i boot through live cd.
i will try the init option.

[Edit] init= didn't work. i changed the boot line in grub.
but are you sure about it? if this actually worked it would be a huge
security blunder right?

N.

It should work (though maybe something VM-related is interfering). It's one reason why one should lock down the BIOS, the boot order, and the bootloader on machines where untrusted parties can gain physical access.

 

[Nithin]

i see. then i dunno why it didn't work. i changed it like you said. it did the same thing it normall does.
went upto the graphical login.

 

[n0cmonkey]

Boot into single user mode and change it there. I don't know how grub does it, check the man page.

Don't mess with the permissions of things outside of ~/.

 

[xtknight]

To get in a root terminal try Rescue or Recovery mode??

Well once you're in the root terminal you need to do

chown root /usr/bin/sudo
chmod 4111 /usr/bin/sudo

I think that should do it.

I did the same stupid thing to my friend's Ubuntu and he said he fixed it with those commands I later told him. Just wondering, did you change the permissions of the whole /usr/bin directory or just sudo? I actually changed my friend's whole /usr/bin directory by mistake and we just decided to reinstall it. Even though we fixed sudo, lots of other things got screwed up.

 

[TanisHalfElven]

Originally posted by: Nithin
my first thought was the live cd option. the prob is that its a vmware install. it doesn't see the virtual hdisk when i boot through live cd.
i will try the init option.

[Edit] init= didn't work. i changed the boot line in grub.
but are you sure about it? if this actually worked it would be a huge
security blunder right?

N.

yeah single use mode should do it.
enter it
type
deluse <username>
adduser -u 1000 -g admin <usename>

might want to check the command using tabb cuiz i am not sure about spelling and stuff.

 

[Nothinman]

[Edit] init= didn't work. i changed the boot line in grub.
but are you sure about it? if this actually worked it would be a huge
security blunder right?

You are changing it on the kernel line in grub, right? Just add init=/bin/bash after the root=/dev/blah entry.

And no it's not a security blunder that you can do this, the real blunder would be you allowing untrusted people to physicall access your machine.