It probably is.
Their IPs are all from Australia, some of their char names are Xiao, Soulfire, Clutch, Treble, Med, etc etc. I heard they were also banned from Opal RO, but I'm not sure as to why.
And looking into it further, it wasn't an SQL injection. I have tested my server many times to see if SQL injection would work, so far we've been safe.
One of the players in Syndicate kept trying to get people to go on his test server, I'm guessing he got their PW that way.