Access Control

Many companies set very simple access permissions. You must be
wary that networks are designed to increase interoperability so that it
is a simple matter for a user to click on his “Network Neighborhood”
icon in Windows and see all the wired and wireless devices on his network
segment.
Does your company have a policy to set passwords for network
shares? Do you know who is sharing what, and with whom? Some users
want to share a document from one employee to another so they just
share “Drive C” on the network. But if they don’t remember to turn off
the sharing, everyone within that network segment has full read and
write permission to that user’s Drive C. If there is a virus running
across your network, you can bet that that user’s computer is fully vulnerable
and will most definitely be compromised.
Wireless networks not only have all the same access control vulnerabilities
as wired networks, but they can easily be accessed by outsiders.
The most common type of attack is simply to sit outside an office building
and use a wireless network interface card to roam onto any available
802.11b network. Since the majority of users fail to set even the simplest
access control barriers that prevent a random user from accessing the
network, everything on your network becomes vulnerable to attack,
theft, or destruction from a virus.