The system serves almost 6,000 residents in Raleigh.
The RHA said it noticed the breach Thursday morning when several workers reported being locked out of their computer system.
"We immediately notified state and federal authorities, met with Emergency Management, and currently have the National Guard cyber security team on-site investigating any potential data breach," RHA CEO Ashley Lommers-Johnson said.
The agency said it is taking the appropriate steps to update information for anyone affected by the attack. Residents are still able to submit maintenance needs through a work-order calling line.
"We are taking all appropriate actions to identify the threat actors, determine which systems were penetrated and return to regular business operations," Lommers-Johnson said.