We have multiple customer sites which provides login via mobile number OTP option (new & registered users). Recently, we come across an incident where a user received 100+ OTPs with in few minutes to login to 10+ different websites multiple times. Attempts made on few unfamiliar websites as well.
- Which type of attack this is ? and how it is possible ?
- How to understand whether those OTP were used for login & collect information ? or just to create cyber fear ? (Not all customer sites are providing new device login notification like social networking sites)
- How we can prevent this? (No restrictions on the sites and mobile number can't be kept as secret)