Fail while experimenting with passwd file, need your help!!

L00PeR
7 years ago

0

Hey :(
Let me put you on situation, I was reading something about security about the /etc/passwd file (used for making backdoors) when I sarted tinkering with it.
First I thought, what would happen if I change the UID and the GID of my user to 0, well first, in the prompt was written: I have no name!
This was weird, I guess this happened because when you login, you create a kind of session with a UID and a GID, and as the ID’s of my user were changed, the system didn’t knew who I was.
This had a very simple solution, just pressing Ctrl+Alt+f1 so another shell opened and I could login with my user, which instantly converted into root.
Wooohooo so nice!!!
Then I thought, what would happen if instead of changing the ID’s of my user to 0, I change the ID’s of the root to 1000(the ID of my user).
Well the hole system crushed, I cannot even start Ubuntu (only in recovery mode).
And when I start it on recovery mode and select to open a shell as root, the system doesn’t know who I am, as on the passwd file there’s anybody with UID and GID 0, so I loose my superuser powers….
Any help?
Thank you in advance

Human Stupidity , thats why Hackers always win.
? Med Amine Khelifi

L00PeR
7 years ago | edited 7 years ago

0

OMG, DONE!!!
uff such a big scare xD

I didn’t wanted to lost my bot xD

The solution to the problem was simple:

Start another OS, you can do this form a live CD or just selecting one already installed.
Then execute this command:
mount /dev/sdaX /mnt
WARNING: You must change the ‘X’ to a number, if you don’t know in which partition is your linux, just try them all and check whats inside the /mnt folder, you should identify your OS by looking at the files!!
Then go inside the /mnt folder and change whatever you want to change, WHATEVER!!!!!
Then you just need to reboot your system, because somehow, changes on your /mnt folder are saved to the real partition!!

In my case, I just needed to open the /mnt/etc/passwd file and change the UID and the GID of the root on /mnt/etc/passwd

This is awesome!!!
Because you can access whatever you want on your computer!!
Now I understand why experienced hackers say that if you have physical access to a PC, you can do whatever you want!!

Human Stupidity , thats why Hackers always win.
? Med Amine Khelifi

Reply has been removed

L00PeR
7 years ago

0

I was waiting for someone to ask something :)
If somebody wants to, you can pm me :)
closing…

Human Stupidity , thats why Hackers always win.
? Med Amine Khelifi