Port Probe TCP Port : 1053

Remote Assistant (RA)

Port Number Decimal = 1053/TCP

BIND name servers choose a source port to use for outbound queries when they start, which means you must allow DNS messages from any unprivileged port. For example, you can programmaticly  instruct a name server to use port 1053 as the source port for all outbound.

Some trojans and keyboard loggers uses this port.  "The Thief" Trojan runs on TCP port 1053. If you suspect something is going on, about the only way to be sure it is not a remote sort of deal is you need to sniff in/out traffic.