First and foremost, I am sorry for posting anonymously for security reasons. Exposing my identity might mean exposing my vulnerability, which comes from the problem decribed below.
I have accounts in websites A1,A2,A3,...etc with password X or derived from X in some pattern.
When registering at website B, I accidentally entered X in the username field. The registration flow was: I entered my email address, I clicked the link in the email they sent, and then they ask a username, which I mistook as a password field. They didn't ask any other information, so right after I entered X as username, I was registered.
The problem is:
- X, my password for A1,A2,A3,...etc is stored in plaintext, and
- in website B, username is public, which means everybody can see X.
One obvious solution is to change my passwords for A1,A2,A3,...etc. However, it can only be done to websites I remember. I might miss a lot of websites in which I have an account.
Website B doesn't seem to have a mechanism to change username or delete account. I have tried contacting them however there are issues with that:
- The technical support claims not to understand my explanation of the problem
- There might be some restrictions which prevents them from changing my username or deleting my account.
Is there any possible solution for this?