Comcast is doing some clean-up work this week on a recently discovered data breach. An initial list of 8,000 Comcast usernames and passwords was unearthed over the weekend on the document-sharing Web site Scribd. Comcast was alerted to the list Monday and immediately had it pulled down for analysis, said Charlie Douglas, director of communications for Comcast's high-speed Internet product. The company is now working with "the proper authorities" to investigate the leak.