According to APP, the details of Communications-Electronics Command (CECOM) and Command, Control, Communications, Computers, Intelligence, Surveillance and Reconnaissance (C4ISR) personnel were accessed by the hackers.
Nongovernmental personnel and Fort Monmouth visitors are also affected by the breach.
The hack, discovered on December 6, exposed names, dates of birth, social security numbers and salaries, Army representatives said. After the incident, the targeted databases have been taken offline.
CECOM and C4ISR were relocated from Fort Monmouth to Aberdeen Proving Ground back in September 2011.
The affected individuals are being offered one year of free credit monitoring services.