The breached server belonged to the UNC School of Medicine and contained information that was collected as part of a federally funded mammography research project. The system contained records on a total of 236,000 women, of which about 163,000 included Social Security numbers.

Matt Mauro, chairman of the university's Department of Radiology said the breach was first discovered in July when a researcher reported problems accessing the system. A subsequent investigation by the school's information systems staff revealed that the system had been hacked.

Though the breach was discovered in July, there are indications that the actual intrusion may have taken place as long as two years ago, Mauro said. "We think we found some viruses that date back to 2007," he said.

The breached server received information from 31 different sites across the state, Mauro said. When the breach was discovered, the system was taken offline immediately and has remained that way since July, Mauro said.

The sites that were sending the information to UNC have stopped doing so for the moment, while stronger precautions are implemented to prevent a similar breach in future, he said.