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Old 06-24-2002, 10:40 PM   #1
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Keeping the previous administrator OUT

I've just taken over administration duties of a Linux box, but don't know much about Linux. (scary!)

Anyway, the previous owner of the box left under less than pleasant circumstances. Now, the major concern is making sure he can't get back in to do damage.

Obviously, I will change the root password. I've also used the "userconf" tool to identify any other user accounts that are in the "root" group. Those accounts will be deactivated.

I'm also concerned about our mySQL database. I will have to change the root password on that too, correct?

What other things should I check? Are there any other possible back doors I should know about and close? Are there any other user groups or logins that should be checked/changed?

Old 06-24-2002, 11:44 PM   #2
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also check accounts that have the remote access, such as telnet, ssh and so on.

if that box which u are taking over, using an static ip, try to change a new ip too.

Last edited by shoot2kill; 06-24-2002 at 11:46 PM.
Old 06-25-2002, 12:22 AM   #3
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check accounts that have the remote access, such as telnet, ssh and so on
Do you just mean regular user accounts that have such abilities or some other kind of account? How do I check for such accounts or that they can do that.

Also, in "userconf" I see the user "operator" -- is that root or something else Linux specific -- meaning I shouldn't delete it?

Old 06-26-2002, 11:28 AM   #4
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if you wanna be on safe side, delete all /bin/bash from /etc/passwd for users that do not log in locally/telnet/ssh

make sure to change smbpasswd for root (ifany)
change all passwords for mysql admins
Old 06-26-2002, 09:01 PM   #5
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you may have a more work cut out for you.

if you are running mysql. you may need to change other passwords for it as well. if your webserver has a password (in mysql) , odds are he may know that as well.

check your last log often and see who is logging in. he may have a back door or two set up.
Old 06-26-2002, 10:11 PM   #6
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Honestly, if you're that worried and the guy was competent, copy the SQL Database late one night, get another machine, install whatever X distro from the ground up, put the SQL DB on it, and then hammer at it until all of the proper accounts and services work. Add users back in as they become apparent. That's a nuclear approach, but really:

Earlier you mentioned "userconf" the GUI tool, which I think is built to ignore any userIDs below 500, which is conventionally where normal users start. Below 500 is system users, like "mail" and "nobody" and "apache". You may want to see if there are some users in /etc/passwd down there in the teens that aren't supposed to be, especially if they have bash as a shell instead of sh, that's kind of telling. Also, make certain you're not running sudo, and if you are, make sure you can trust the security of any of the user accounts in it.


Old 07-18-2002, 11:07 AM   #7
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also remove any keys in /root/.ssh xso he cant use keys to log in
Old 07-28-2002, 08:36 AM   #8
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Exclamation look out!

i had the very same trouble a few weeks ago i took over a linux box

basically i went through the passwd file and had the ip address and dns records updated on the web
Plus check you cron jobs for strange scripts.

the boxes previous owner put a script in there to create a user and password then email the boxes new ip address to him.

keep your eyes open!


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