NCR SelfServ ATMs running APTRA XFS 04.02.01 and 05.01.00 implement 512-bit RSA certificates to validate bunch note acceptor (BNA) software updates, which can be broken by an attacker with physical access in a sufficiently short period of time, thereby enabling the attacker to sign arbitrary files and CAB archives used to update BNA software, as well as bypass application whitelisting, resulting in the ability to execute arbitrary code.