A set of electronic keys that was stolen from a Canberra security business on Monday night could have been used to access all automatic teller machines across the state, police said.
The keys were taken from the premises of an unnamed security firm. Within hours, they were used to access cash from five separate ATMs across Canberra and Queanbeyan.
The keys have since been disabled. Police said all banks operating in the region could have been affected by the theft prior to the cancellation.
"The manfacturer of all the ATMs in Canberra is the same, as is the technology used, meaning the key could access all ATMs," a police spokesperson said.
NCR and Diebold are the two biggest ATM manufacturers in Australia. NCR did not respond to request for comment by the time of publication.
Diebold said it manufactured a small number of ATMs in Canberra, and said it was "highly unlikely" one manufacturer covered the entre Canberra ATM market.
ACT Police said the key was electronic but would not confirm whether it included a chip or token.
According to security sources, ATMs are generally protected by a pin pad lock behind which the master key sits.
The pins are known only to service staff, and the ATM cannot be opened without both a pin and key.
ATMs are also protected by an electromagnetic alarm that is triggered if the machine is accessed outside of scheduled service times, industry experts explained.