I setup my website to require unique email addresses (no two users can have the same email address), but I realized that this could allow someone to check if a person is registered on my website by attempting to signup with that email. Granted that this person would have to know the email address they wanted to try, but it could be useful information for some people (e.g. competitors who wanted to see if their users are registered on my website).
Is there any real way to stop this, or does this just have to be accepted as a possibility?
Edit: just to be clear, this is about creating an account. Even you provide a generic "invalid login" for bad logins, how would you require a unique email address or username without disclosing which usernames or email addresses are valid?
Additional, much later edit: One thing that wasn't considered here was maintaining the requirement for unique email addresses when you let users change their email address after account creation. Here, the solution I accepted of sending a "forgot password" email doesn't work nearly as well. Instead, it seems that the only options are to use captchas or limitations on the number of times an email address can be changed in a certain period of time to limit automated attempts.
If someone tries to sign up with an existing account — send a "Change your password" email instead of a "New account" email (and explain why).
Leave the HTTP response as a simple "A confirmation email has been sent to the address you specified. Follow the instructions in it to continue".
I suppose the issue is if someone forgets their password, you would ask them to enter their email address and you would send the password there if a match was found?
For that you can have users supply a question/answer challenge when they register their email address. Its a bigger pain for your users but if security is a concern then they may go for it.
Another possibility is your registration form. In this case users can enter an email address to see if its already "taken".
To address your concern you should just happily accept all registrations and send a confirmation email, even if they are already registered. That way the user doesn't know if they just registered the email address for the first time or not.
Finally, if an incorrect username/password is given, don't tell the user which is bad.
I don't think it's a terrible security risk unless membership to the site is sensitive, in which case you can use some of the patterns described.
Yes, that can happen and you cannot really do anything about it except limiting the number of checks/registration attempts in time. That will at least prevent automated checks by your competitor. Of course, if some guy decides to check if his girlfriend is registered there, then he will have that possibility.
Just a thought, not sure if it would work, but why not do something like the login page, where instead of saying "your password is wrong" it says "your username or password was wrong". Maybe just state "your email address is invalid". It's probably a bit of usability error, but if you are concerned about people doing as you say, then you might have to live with it.
Related
I'm developing an web application using Django.
Currently I am working on sending "reset password link" thorough email (amazon simple email service - SES)
The mechanism I used, is the same with the answer of "simeonwillbanks" below link
Secure ways to reset password or to give old password
Give users a reset password option.
This option saves a unique token for a user. The token eventually expires (hours, day or days).
A link is emailed to the user which includes the token.
User clicks on the emailed link.
If the token exists and isn't expired, the link loads a new password form. If not, don't load the new password form.
Once the user sets a new password, delete the token and send the user a confirmation email.
What I worry about this, I am not sure this way is safe in terms of security. What if the email is captured by a hacker?
I tested on several major websites how they care this.
get an "reset password" email and copy the link.
give the link to other and see if he can change password on my account.
From this test, I figured out that somebody else also can change my password only with the link.
If I cannot do anything on the link, is there way to make email more secure?
like as the mechanism of ssl(https) on website?
Thanks!
It's somewhat secure, though is toast if the user's email was compromised.
I prefer using an HMAC in the URL, which avoids storing tokens in the DB.
If you include the user's IP address in the URL, and in the HMAC, you can be sure the reset link click came from the same computer (router actually) that requested the reset, and that it can't be shared.
Instead of the IP, you could set a device cookie with the username/email and an HMAC, and then check this when the reset link comes in from the email.
The system should ask the user the answer to a secret question after he clicks the link. Even better, send an SMS to his mobile with a short random code and ask for that. This is called https://en.wikipedia.org/wiki/Multi-factor_authentication
Then show the change password form (over HTTPS of course).
While we're here, you should display the same "success" message whether or not the user has an account, to avoid user enumeration attacks.
Also, use a localhost MTA relay or asynchronous email so that a hacker can't tell whether you sent an email (a slow response would indicate that a user exists).
I'm creating a forum, and currently trying to decide the most secure method for a user to change their EMail.
I figured it might be best to send a confirmation email to the old address, and once confirmed(after clicking the link in the EMail), their old EMail address will be replaced by their new address.
But I noticed some sites,
Requiring verification from the old email address is a definite boost to security, and should be required for critical sites like banking or high-profile social networking where a hijacked account can do serious damage, but it means users cannot change their email address if they lose access to their email account.
If you're creating a web-forum, then this probably isn't important enough to warrant an explicit release, and there are going to be many users that abandon a forum, let their email address expire, and then return. For this case I advocate simply sending a notification email to the old email address and including an "I didn't request this, please revert my email address immediately" link, that way in case of a hijacked account the original account-holder is still able to reclaim the account, while not inconveniencing those who genuinely no-longer have access to their old email accounts.
I am currently developing a c# web application that allows users to login with a password. A feature that I need to include is a forgot password function.
What is the recommended process for forgot password?
I was considering this:
User clicks forgot password, enter email address
Email sent
Click on link in email (link only valid once and within time period)
Taken to the site and asked to enter new password (should they also give answer to security question?)
Password changed, email sent to user of such
User now can log in with new password
Your idea looks solid, but I would add some other considerations:
Be sure that the token you are generating in the email using is using a the .Net Framework crypto classes designed for randomization, not something that seems random but is not designed for that purpose.
Take no action on the account from the sending of the reset email (otherwise people will be able to lock other people's accounts if they know their email)
Add a rate limiter on how many resets per hour can be generated for a given email. Otherwise somebody could DOS a user by: (a) using x bad passwords to lock the account and then (b) generating reset emails for them faster than the email system can deliver.
Where possible defer to other systems such as OpenID. It's easy to get things wrong when you roll your own.
We have two ways to retrieve the forgot password:
1. Through registered email id
2. Through registered mobile number
Registered Email id:
a. Ask the user to provide the registered email id
b. The system checks the provided email id is available in the DB or not
c. If Email ID is there in the DB then system send the Email to reset the password but if Email id is not there in the DB then system show the alert messaged.
d. The user must provide strong password while resetting the forgot password.
e. Password reset successfully and is also change in the DB with respect to the Email ID.
Registered Mobile number:
The process is almost same as the email but in this case, OTP will be sent over the registered mobile number.
We need to integrate the 3rd part SDK for this or we can use the imessage in IOS.
I have a registration form in my website. I don't want to give away information about the existence of an e-mail address for security reasons. How should we, security wise, handle the "e-mail already exist" scenario without giving this information away?
Theoretically, its impossible, think about the email as the user name, you will inform the user that the user name is already reserved or taken, the same applies for the email address.
You can let the user enter his email twice by typing to ensure that he didn't enter other email by mistake, how ever, if the user entered his email wrongly twice, then, its his problem!
On the other hand, you won't send the confirmation email for already confirmed users, also for emails that are not stored at your side, you need to put this message in your confirmation emails:
If you are not {First Name + Last Name} then please ignore this email or something similar.
I hope this will help.
You could make it so the user can create an account / sign in with openid/google/facebook/yahoo. That way those sites hand the auth and if they can log in successfully through those you can collect any additional information you need.
You could alternatively have them create an account by first only providing an email. You would email the user with a link where they could continue the registration process if they don't already have an account. If an account is already created you can send an email saying something like: a request was made to create an account using this email address, but an account already exists. If this wasn't you then....
I want to create a newsletter app and users will naturally have to confirm that they signed up for the newsletter so we don't spam them if some bot entered addresses.
My idea was to simply send the user an email that contains a link that has a secret in the url, which is a hash of the email address and some secret sitekey.
My questions is the following:
Can someone by registering a few accounts and thus receiving the hash of the secret with his address, guess the sitekey and thus register every email address she wants?
I don't see anything that could be gained from doing that, but if it is very easy, chances are someone will do it and I get blacklisted.
My reason for not storing a non activated user account are simply that I don't want to purge them from the DB every x days.
If you ensure you use something like sha1 with a completely random salt/sitekey, then it would be futile to attempt to reverse engineer the sitekey with a dictionary attack.
If someone did want to synthesise their own hashes to register arbitrary addresses, a more effective use of their time would be to gain access to your server to read the source code :)
I think it would be best to generate a random secret and keep it in the db. That way there is nothing that can be guessed. (At least not nothing that grants permission to add any email).