Re: Linux auto idle logout & vlock possible security problem

From: Jim Dennis (jimdat_private)
Date: Sun May 31 1998 - 01:18:47 PDT

  • Next message: Peter van Dijk: "Re: First patch :)"

    > There's a possible security problem using auto idle logout programs and vt
    > lockers.
    > Try the following:
    > get the pid of your shell,
    > (sleep 10s ; kill -HUP <pid-of-your-shell) &
    > vlock -a
    >
    > after vlock -a, you can't change the virtual console on a Linux terminal.
    > But if you log in, start vlock -a, enter your password you can change
    > vt...
    >
    > The same happens when an auto idle logout program logs you off. The vlock
    > (maybe lockvt also)  program doesn't terminate itself after a SIGHUP,
    > which is ok, but after this, anyone can log in, start vlock -a, enters
    > his/her password, and get full access to the console.
    >
    > Possible solutions:
    > - don't use vlock/lockvt
    > - don't use auto idle logout program
    > - as root, never leave your terminal. log off.
    > if you want to leave, use screen, detach it and log out.
    
            Are there any known security issues with 'screen'?
            I personally suggest patching the sources to force
            it to put its socket (unix domain) in ~/tmp/.screen
            --- so users can make sure that the directory has
            appropriate permissions.
    
    
            Has anyone vette'd the code?
    
    --
    Jim Dennis  (800) 938-4078              consultingat_private
    Proprietor, Starshine Technical Services:  http://www.starshine.org
    



    This archive was generated by hypermail 2b30 : Fri Apr 13 2001 - 13:55:56 PDT