
Most accounts have special files called "dot" files.  These files
control the startup, environment, and execution of the shell and some
programs.  It is very important that these files not be writable
or owned by anyone but you!  If someone else owns or can write those
files, they can take control of your account in a matter of minutes!
Then they'll be you, which means they can do anything you can do: read,
write or modify files; send mail; talk to other users; print
documents.  Make sure that permissions on these files are set to 644,
or, better yet, 600:

.login     .logout    .cshrc    .bashrc    .kshrc     .xinitrc
.dbxinit   .profile   .sunview  .mwmrc     .twmrc     .exrc

[Excerpted from "Guide to Account Security"]
