[tlug] security dude....the puto story

[Pietro Zuco <pietrozuco@example.com>]

Hi TLUG Folks.
I just was playing with users in my system and I created a user called puto.
There are two stories about two security situations, sorry if the text is too 
long :-)

STORY 1

I don't understand a thing that in my ignorance I consider a bad security 
behavior. The steps I did was:

1. useradd puto
2. passwd puto
3. logged as puto
4. I added in the .bashrc file at the end "mc" because I wanted that every 
time that puto login the mc starts
5. I thought that puto can change this situation so I became root with su 
command. I typed chown root.root .bashrc
6. The .bashrc file has 644 atributes, list with ls -l and I confirm that the 
.bashrc file now is of user root and group root
7. exit root so I'm puto again
8. edit the .bashrc file with vi
9. The vi alerts me that the file is read-only
10. I change the content of the file and put the mc line in comment
11. quit vi with wq! option, and it says "written!!"
12. list with ls -l 
I surprise because the file .bashrc now is of puto again! the user and group 
are puto and puto!

How can puto change the propietary of the .bashrc file?

STORY 2

1. I'm logged as puto
2. I became root with su command
3. In the puto directory I created a text file called helloroot with some 
stupid text.
4. I list with ls -l and the file was of root and group root.
5. I exit root and became puto again.
6. I created a dir in the puto home dir called putodir
7. I changed to that directory
8. I created a text file with the same name I used before, "helloroot" with 
some other stupid text again.
9. I copy that file into the puto home dir with de -f option "cp -f helloroot 
/home/puto"
10. Change to puto home dir
11. I listed with ls -l and the helloroot file now is of user puto and group 
puto and was overwrited.

I think it do not have to happend because that file was of root isn't it?

Again I don't understad. Maybe all this is because the puto home dir is of 
user puto and group puto?

Thankyou in advance and sorry for le long file.

Pietro.


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