Skype Security Flaw
The researchers found several properties of Skype that can track not only users’ locations over time, but also their peer-to-peer (P2P) file-sharing activity, according to a summary of the findings on the NYU-Poly web site. Earlier this year, a German researcher found a cross-site scripting flaw in Skype that could allow someone to change an account password without the user’s consent.
“Even when a user blocks callers or connects from behind a Network Address Translation (NAT) —a common type of firewall —it does not prevent the privacy risk,” according to a release from NYU-Poly.
The research team tracked the Skype accounts of about 20 volunteers as well as 10,000 random users over a two-week period and found that callers using VoIP systems can obtain the IP address of another user when establishing a call with that person. The caller can then use commercial geo-IP mapping services to determine the other user’s location and Internet Service Provider (ISP).
The user can also initiate a Skype call, block some packets and quickly terminate the call to obtain an unsuspecting person’s IP address without alerting them with ringing or pop-up windows. Users do not need to be on a contact list, and it can be done even when a user explicitly configures Skype to block calls from non-contacts.