SNMP can be easily used to make changes to your network devices. Though the name "community string" seems harmless, a community string is really a password to access your device. RW means that the community string can be used to make any change to that device that is available including erase the configuration, change routes, add passwords etc.
You have effectively published the password to your network since community strings are usually configured the same on all similar devices. I recommend that you immediately change your community string since you are a bank and have published this information.
