I used to have individual vaults that I synced to Dropbox when I first started using 1Password in 2010; since then I have moved to family based vaults. We know that Dropbox had a data breach in 2012 which resulted in email addresses and password being exposed.
Let's assume someone got hold of my 1Password vaults that were then stored in Dropbox. What would they need to access the data? Do they only need to guess the master password? And which master password do you need? I'm asking this question as I'm still able to log into my 1Password client on my iMac or iPhone using the master password from the individual vaults even though I have given the family-based vaults a newer and much stronger master password.
1Password Version: 7.2.5 (70205002)
Extension Version: 7.2.5
OS Version: 10.14.3
Sync Type: Family