Code posted online that can skim the last known IP address of users is being checked out by Skype as a possible security flaw.
The software,
posted on Pastebin, works on a patched version of Skype 5.5 and involves adding a few registry keys that allow the attacker to check the IP address of users currently online without calling them.
Services like Whois will then give some other details on the city, country, internet provider and/or the internal IP-address of the target.