Low mortgage rates have led to a boom in home borrowing -- and a surge in fraud. The F-B-I says the nation has a near epidemic of mortgage fraud. So far this year, mortgage companies and banks have made more than 12-thousand reports of suspicious activity, compared to only 42-hundred during all of 2001. One common mortgage scheme is "property flipping," in which property is purchased, appraised fraudulently at a much higher price and then quickly sold. In a foreclosure, a lender can be stuck with a home actually worth much less than the loan that was issued. Other scams involve fake identities and credit histories, use of "straw buyers" to conceal the true buyer's name, and forged loan documents.