Thanks for letting us know. You could always be silent about this issue and avoid potential PR problems.
If SafeDice wasn't compromised by any form of attack, then do you have any suspicion or theory which other casino/dice service was breached?
Was there any reports from users who complained that their online balance was stolen recently or they noted other suspicious activity?
I don't store plain text password, and the encryption that I use is invulnerable to rainbow attack. My theory is that the breached service ( it doesn't have to be dice / casino site ) is not a new service, it has more than 10k active bitcoin users. One of the potentially breached account was from an old user of Safedice that I know, this is the reason of my concern.
So far I don't think there was any report linked to this case. I think most of the breached account that does not use 2FA has very low balance.
Any further information re the source of these failed login attempts? Perhaps an email confirmation before withdrawal will help? or maybe withdrawal only allowed for logins using ip addresses from the same country/region?
You can use ip to verify if those accounts were opened from the ip user most often use to sign in. Otherwise send a confirmation msg to the user's email so that they can open the account from the link sent to their email or lock that account and post a notification on your site that any user who's account locked can contact you or support to get them unlock with some details like email or btc address he oftenly withdraws to.
I considered this one, but I prefer our users to be anonymous. I have disabled withdrawal for suspicious account.
I think the breach was from Bitsler.com . The admin doesn't want to reveal, but there are some account leaks happening from Bitsler website. Over 17k accounts plain text had been leaked here and another places.
I think this is very dangerous for the Bitcoin community, and bitsler admin should take some action! Many bitsler users are claiming they got their account hacked and I had my bitsler accounts stolen too.
I don't want to accuse anyone , I'll leave any judgement to the community