What is Data Seepage ?
"Information that is broadcast or available via simple inquiry or spoofing that may not by itself seem critical but become more important as pieces of a larger puzzle".
To make things simple Data Seepage can also be called as a passive form of social engineering, the reason is it helps you get the information that will help you to launch further attacks on your victim.
What happens in a Data Seepage attack is when you computer joins a network it performs hell lot of actions like connecting to shared drives, accessing your company intranet homepage or your myspace account which can be used to further launch a series of targetted against you.
A very cool tool which is used to launch Data Seepage Attack is ferret. It is basically a sniffer but captures only the data that can be used to launch further attacks