Skype and Data Exfiltration

by Kenneth Hartman
Sept. 1, 2017 0 comments SANS Institute Encryption & Authentication covert channels

Few software packages have been as controversial, yet as ubiquitous as Skype. Skype is a P2P communication service that has grown to over 300 million users (Steele, 2013). A common question on the Internet is whether Skype is safe for business.1 Many of the responses focus on the fact that Skype software is closed-source while others are concerned with the privacy of Skype communication (Masnick, 2012; Spirovski, 2008). However, there is another aspect of Skype that makes it an undesirable software package for a managed network that contains sensitive information. Skype uses standard cryptographic primitives to achieve strong end-to-end encryption (Berson, 2005). While this encryption provides the important benefit of protecting the information transferred, the Skype application sends its traffic to an ever-changing series of intermediate peer nodes around the globe (Skype Limited, 2010)