An anonymous reader writes: As if it weren't enough that one bogus ATM was discovered collecting card details at the Riviera in Las Vegas where Black Hat and Defcon attendees were staying, one presenter suspects that ATMs at the Rio were compromised as well. Chris Paget tried to take out $200 and the machine never gave him the money despite debiting his account. At least five other people were affected. The hotel staff allowed the machines to keep running and threatened that Paget could be prosecuted for vandalism if he unplugged them. The Secret Service confirmed on Monday that they're investigating. It could be an inside job, or the machines may be infected with malware, as was found earlier this year in Eastern Europe.