The primary problem with legacy software is keeping it secure.  Many businesses are using software that was developed years ago and before many of these new attack variants were ever even considered.  That means that they were not designed with the necessary protection required. When businesses use these types of software on systems that hold their sensitive business data without proper security they are setting themselves up for the distinct probability of an attack that could cost them their businesses with hackers constantly on the lookout for companies using these older systems.

Sometimes it is almost impossible to stop using these types of legacy software systems as they are an integral part of their business processes with other proprietary programs relying on them.  In this case, it is important that you look to professionals that can help you secure them from hackers.