Credit unions instinctively want to help members affected by hurricanes and other natural disasters, but few expect or prepare for increased fraud attempts that may follow.

Just ask executives at the Harahan, La.-based ASI Federal Credit Union, which was slammed by Hurricane Katrina in 2005. To help affected members, the credit union, which today has $313 million in assets and 56,000 members, raised its offline ATM limits. Shortly after, nearly 10,000 of the credit union's 80,000 members overdrew their accounts by almost $4 million. Though many members later corrected their shortages, some, then-CEO Audrey Cerise said at the time, "just sat in front of the ATM, playing them like slot machines" with no intention of replacing the funds.

Or ask Issa Stephan, president/CEO of the Freehold, N.J.-based First Financial Federal Credit Union, whose members endured flooding and other damage after Hurricane Sandy in 2012. The credit union offered a variety of accommodations to members, including payment plans, advances, and even food and clothing. But because its systems were hobbled after the storm, one person was able to withdraw $70,000 on a home equity line that was actually already closed.