Using Apache, it is quite simple to set up a page that uses basic access authentication to prompt a user for a name/password and use those credentials in some way to grant access to that user.
Is this secure, assuming the connection between the client and server is secure?
The worry about basic auth is that the credentials are sent as cleartext and are vulnerable to packet sniffing, if that connection is secured using TLS/SSL then it is as secure as other methods that use encryption.
This is an old thread, and I do not believe the highest voted/chosen answer is correct.
As noted by #Nateowami, the security stack exchange thread outlines a number of issues with basic authentication.
I'd like to point out another one: if you are doing your password verification correctly, then basic authentication makes your server more vulnerable to denial of service. Why? In the old days, it was common belief that salted hash was sufficient for password verification. That is no longer the case. Nowadays, we say that you need to have slow functions to prevent brute forcing passwords in the event that the database becomes exposed (which happens all too often). If you are using basic auth, then you are forcing your server to do these slow computations on every API call, which adds a heavy burden to your server. You are making it more vulnerable to DoS simply by using this dated authentication mechanism.
More generally, passwords are higher value than sessions: compromise of a user password allows hijacking the user's account indefinitely, not to mention the possibility of hijacking other systems that the user accesses due to password reuse; whereas a a user session is time-limited and confined to a single system. Therefore, as a matter of defense in depth, high value data like passwords should not be used repeatedly if not necessary. Basic authentication is a dated technology and should be deprecated.
The reason why most sites prefer OAuth over Basic Auth is that Basic Auth requires users to enter their password in a 3rd party app. This 3rd party app has to store the password in cleartext. The only way to revoke access is for the user to change their password. This, however, would revoke access for all 3rd party apps. So you can see what's the problem here.
On the other hand, OAuth requires a web frame. A user enters their login information at the login page of this particular site itself. The site then generates an access token which the app can use to authenticate itself in the future. Pros:
an access token can be revoked
the 3rd-party app can not see the user's password
an access token can be granted particular permissions (whereas basic auth treats every consumer equally).
if a 3rd-party app turns out to be insecure, the service provider can decide to revoke all access tokens generated for that particular app.
Basic auth over http in an environment that can be sniffed is like no auth, because the password can be easily reversed and then re-used. In response to the snarky comment above about credit cards over ssl being "a bit" more secure, the problem is that basic authentication is used over and over again over the same channel. If you compromise the password once, you compromise the security of every transaction over that channel, not just a single data attribute.
If you knew that you would be passing the same credit card number over a web session over and over, i'd hope that you'd come up with some other control besides just relying on SSL, because chances are that a credit card number used that frequently will be compromised... eventually.
If you are generating passwords with htpasswd consider switching to htdigest.
Digest authentication is secure even over unencrypted connections and its just as easy to set up. Sure, basic authentication is ok when you are going over ssl, but why take the chance when you could just as easily use digest authentication?
As the name itself implies, 'Basic Authentication' is just basic security mechanism. Don't rely on it to provide you with worry free security.
Using SSL on top of it does makes it bit more secure but there are better mechanisms.
Related
I have ASP.NET MVC app that uses Forms Authentication. After user is authenticated, in response he will receive forms cookie that contains auth information. Now regarding the forms cookie: It is encrypted by a machine key and it is protected from tampering by signature. I also use HTTPS... However, what if somehow I get the cookie and try to make request from another client (meaning that the request will be made from another IP address)?
It seems to me that this scenario will work. Are there any ways to defend from this kind of attack?
If you are using HTTPS everywhere on your site and set requireSSL="true" on your system.web/authentication/forms element in web.config, you are instructing the browser to only pass that cookie back over an HTTPS connection. This will protect against the vast majority of traffic sniffing-based session hijacking attacks and you should definitely use it if your site is HTTPS only.
Forms Authentication is inherently stateless. The server is encrypting the following information and storing it client-side: CookiePath, Expiration, Expired, IsPersistent, IssueDate, Name, UserData, Version. Assuming your machineKey hasn't been compromised, the client will just see this as a blob of encrypted data. When it presents that blob to the server again, the server decrypts it and converts it back into a FormsAuthenticationTicket, validates the fields in the ticket against config, verifies that the ticket isn't expired, etc. and decides whether to treat the request as authenticated. It doesn't 'remember' anything about which tickets are outstanding. Also note that it doesn't include the IP address anywhere.
The only real attack vector I can think of if you are HTTPS-only, take care to protect your machineKey, and set the forms auth cookie to requireSSL would be for an attacker to target the client's browser and/or computer. Theoretically they could steal the cookie from memory or disk out of the browser's space. It might be possible for a virus/trojan to do this or even a malicious browser extension. In short, if a user could get their hands on a valid, non-expired Forms Auth cookie, they could present it from any machine they wanted to until it expired. You can reduce the risk here by not allowing persistent auth cookies and keeping your timeouts to a minimum.
If they had the machineKey, they could create FormsAuth cookies from scratch whenever they wanted to.
Oh.. Can't forget Heartbleed. If you had a load balancer or reverse proxy that was using an insecure version of OpenSSL, it's possible an attacker could compromise your private key and intercept traffic over HTTPS connections. ASP.NET doesn't use OpenSSL, so you're safe from this in a pure-MS stack. If you ever hear anything about a vulnerability in MS' SSL implementation, you'd want to patch it ASAP and get your passwords changed and certificates re-issued.
If you are concerned about the browser/machine based hijacking, you might want to take a look at a project I started [and abandoned] called Sholo.Web.Security (https://github.com/scottt732/SholoWebSecurity). It's goal was to strengthen Forms Authentication by maintaining state on the server at the expense of some overhead on each request. You get the ability to do things like revoke tickets server-side (kick/logout a user) and prevent users from moving tickets between IP addresses. It can get annoying in the traveling mobile user scenario that Wiktor describes (it's optional). Feel free to fork it or submit pull requests.
The Anti-CSRF features that 0leg refers to apply to the UI/form mechanism that initiates the login process, but to my knowledge there is nothing in the Forms Authentication process itself that relates to CSRF. That is, once the cookie is issued to the client, the only thing protecting it from being bounced between servers is the fact that cookies are restricted to the domains/subdomain they were issued for. Your stackoverflow.com cookies won't be presented to serverfault.com. The browser takes care of that stuff for you.
Are there any ways to defend from that kind of attacks?
You shouldn't. Years ago we have had implemented such feature and abandoned it soon. It turned out that:
a single user making requests from the very same browser/machine but switching between http/https can sometimes be seen from different IP adresses
a single user traveling and using her mobile phone sometimes makes consecutive requests from different IP addresses when her phone switches between BTSes
Just to clarify the terminology, session hijacking is usually referred to the vulnerability where an unauthorized user accesses the session state on the server.
Authentication cookies are different from session cookies. ASP.NET puts a great deal more precautions in safeguarding authentication cookies. What you describe is better described by the term CSRF (Cross Site Request Forgery). As #Wiktor indicated in his response, restricting access by IP is not practical. Plus, if you read how CSRF works, the exploit can run in the user browser from the original IP address.
The good news is that ASP.NET MVC has built in support for CSRF prevention that is pretty easy to implement. Read here.
I know ASP.NET supports various authentication models like, Windows, Forms, passports and recently Claims.
I have an asp.net that prompts user to enter user name/password to login, it then compares the input username/password with the entries inside the user table of the application's Database. So, my question is, what is the term/name for this kind of authentication model? Where does this fall in the above mentioned ASP.NET supported authentication model?
I also see that many of the internet sites that I know uses this same approach.
(note: I'ev kept my App simple, of course it has user registeration/add page, profile table to authorize users, etc)
Windows, Forms, Passport, Claims, etc.. authentication are BROWSER authentication schemes. They are the mechanism the browser communicates with the server to present credentials. They have nothing to do with databases or any other storage mechanism (well, mostly..). Those are just implementation details.
FormsAuthentication uses a cookie to store an encrypted value that tells the server that the user has been authenticated. How the user is authenticated, be it by comparing things to databases, using a service, etc.. is all irrelevant if the end result is that a FormsAuthentication cookie is issued.
WindowsAuthentication is a little different in that the browser and the web server communicate to share a Kerberos ticket to verify identity, or the user enters the username password into a box that the server requests the browser to pop up. In this mode, the server itself manages the way that authentication occurs and the app isn't involved.
BasicAuthentication uses an HTTP Header to send the password in cleartext, well, technically it's an encoded password, but it's well known so anyone can unencode it. Again, the actual method that it stores the data is up to the server, and the server does this without an applications knowledge. The important part is that it's accomplished via an HTTP Header.
The same is true of other types of authentication, which are all just variations on the cookie and/or header mechanisms.
The point here is that Authentication is about how any given HTTP request identifies who the user is to the server, and ultimately the application. Not how the data is stored, or validated. So, since you did not tell us how the server and browser communicate, we can't tell you how your authentication is defined, although almost certainly it is a variation of FormsAuthentication.
EDIT:
Just a little history lesson. The reason it's called FormsAuthentication is because the authentication system does not use a pop up dialog box from the browser to enter credentials, but typically the web page provides an HTML Form for the user to enter credentials. The browser is not really involved in the authentication process at all, other than for passing a cookie as requested.
It should be more accurately called "CookieBasedAuthentication", but the name has stuck and will probably stay what it is. ASP.NET provides a specific implementation called FormsAuthentication, but you can do the same thing with any cookie based authentication scheme (although I do not recommend rolling your own, you will almost certainly make security mistakes).
Some people think that storing a flag in Session is good enough. Do not, under any circumstances, ever use Session to store authentication information. Session cookies are not encrypted and are easily stolen and/or spoofed. Use a well known method.
The other answers might have already showed most of the details. But if we categorize carefully on IIS and ASP.NET levels, below are the differences you should pay attention to,
IIS Authentication
This occurs first, as HTTP packets arrive at IIS level first. IIS supports several ways,
Anonymous (the anonymous user account configured in IIS configuration)
Windows (browser side user)
Basic (browser side user)
Digest (browser side user)
How those authentication methods work at packet level requires you to capture network packets and dive into the conversation at that level.
The result of this authentication is that IIS generates a user token and passes on to ASP.NET pipeline.
ASP.NET Authentication
ASP.NET has several authentication methods of its own,
Windows (here ASP.NET trusts and interprets the user token IIS passes, and determines which ASP.NET user identity should be created and which roles it supports, without doing further authentication on ASP.NET level.)
Forms (based) authentication (where ASP.NET ignores the user token, and uses cookies or similar mechanism to build a high level authentication approach. On IIS side you usually set anonymous authentication.)
Claims based authentication, OpenID, OAthen and so on are similar to Forms based, where they don't care much about the user token generated by IIS.
It is possible to use non-anonymous on IIS plus non-Windows on ASP.NET side to set up the so called mixed authentication.
All the Authentication methods that require the user to input a Username and Password that you maintain are a form of Forms Authentication. This is because you are asking them to fill out a form (Username and Password) in order to authenticate them.
Read more about it Here or Here.
Edit: The answer provided by Mystere Man is much more complete and accurate than mine.
For username/pwd verification - the good websites use https - to avoid sending cleartext password over the wire. If I have a site where I want to do this - i.e. login over https. However - after logging in the rest of the stuff should be over http. Is this possible - if yes, why don't we see too many websites doing this. If not, why not?
You might want to read up on Firesheep. The short form is that this technique allows malicious people to hijack the session.
if yes, why don't we see too many websites doing this
The usual excuse for not using end-to-end TLS/SSL is that it causes the web app to take a performance hit, slow response times etc. This is a very flawed argument for https-sometimes security policy. Not entirely unfounded, but still unjustifiable.
If not, why not?
The thinking is that the only inherently vulnerable aspect of user access control is the authentication phase, i.e. where you supply your username and password to prove you are who you say you are. Organizations are aware of the risk of transmitting the credentials in clear text. After this process however, authorization is carried out server side and the web app trusts you from there on out and there are no credentials to protect any more.
Or are there?
As jszakmeister pointed out very succinctly, the session cookie is every bit as security critical as a username/password pair. Should someone get a hold of that, they might as well have seen the password and username on post-it.
I am trying to create a REST service using asp.net web api and everything is working fine but I have now come across what to do with authentication.
I am a little confused of where to start, here is what I have been thinking.
I have an REST api that consist of a number of resources, each resource will need the user to be registered, so what is the best action for doing this? Should I just send the username and password in the header on each call to the service so I can authenticate on the server using
AuthorizationFilterAttribute
I should at least encrypt it though? I would be interested to know what others are doing, I know there is a concept of creating a token (which I presume will be short-lived) so hence the user would authenticate and then would receive a token, this token would then be sent on further calls to the service. So how would I handle the problem when the token expires?
I also have a resource that is used to register a new user, actually the only things that will be calling this is my clients (Android, iPhone). SO should I leave it FREE of any authentication methods or put a hard coded password or something similar so that at least nobody else can register new users? Bearing in mind that the service will be public on the internet.
I just don't seem to be able to find the correct way of doing this, I certainly want to try and get it right the first time so I don't have to refactor the service completely.
The following link appears to cover some sensible DIY options http://codebetter.com/johnvpetersen/2012/04/02/making-your-asp-net-web-apis-secure/. The "Tokens based on Public/Private Keys" section covers an approach I have used effectively in the past and would maybe be of assistance to you.
At the moment though I am using http://identityserver.codeplex.com/ the Thinktecture IdentityServer with OAuth bearer tokens ("Resource Owner Password Credential" grant type)... I am finding this a very good set of code and examples to work from and have IOS clients obtaining tokens and calling the WebApi.
If you really must secure your registration screen you could maybe use client certificates installed on the devices to authenticate... again the Thinktecture service could help here https://identity.thinktecture.com/idsrv/docs/default.htm?RequestingatokenusingOAuth2.html. Although if you registration process is secure What are best practices for activation/registration/password-reset links in emails with nonce e.g. email confirmations and activations etc. it may be safe to leave publicly accessible - this all depends on your business requirements and desired sign up workflow.
You should at least use Transport Level security SSL but as you suggest message level security e.g. encrypting any tokens is very advisable - the OAuth spec has something to say about this http://self-issued.info/docs/draft-ietf-oauth-v2-bearer.html#mitigation.
Regarding expiring tokens - we tend to expire our tokens with the same frequency as our password changing policy; although keeping the validity time down is important (to minimise impact of token theft) and a consideration to balance against your requirements. OAuth has the concept of refresh tokens Why Does OAuth v2 Have Both Access and Refresh Tokens? some debate and links around this topic here, we are not currently using this approach as the ID server we are using doesn't currently support this.
Keeping your tokens safe is also a consideration e.g. we are using the KeyChain in IOS, but also think about Mobile Device Management policies if possible as if these tokens or passwords are one the device they could be stolen, perhaps look into jailbreak detection, lock screen enforcement etc.
Imagine that you have a simple site with only 2 pages: login.aspx and secret.aspx. Your site is secured using nothing but ASP.net forms authentication and an ASP.net Login server control on login.aspx. The details are as follows:
The site is configured to use the SqlMembershipProvider
The site denies all anonymous users
Cookies are disabled
The are obviously many things to consider regarding security but I am more interested in the zero code out of box experience that comes with the .net framework.
If, for the sake of this question, the only attack points are the username/password textboxes in login.aspx, can a hacker inject code that will allow them to gain access to our secret.aspx page?
How secure is the zero code out-of-box experience that Microsoft provides?
You still have some variables that aren't accounted for:
Security into the data store used by your membership provider (in this case, the Sql Server database).
security of other sites hosted in the same IIS
general network security of the machines involved in hosting the site, or on the same network where the site is hosted
physical security of the machines hosting the site
Are you using appropriate measures to encrypt authentication traffic? (HTTPS/SSL)
Not all of those issues are MS specific, but they're worth mentioning because any of them could easily outweigh the issue you're asking about, if not taken care of. But, for the purpose of your question I'll assume there aren't any problems with them.
In that case, I'm pretty sure the forms authentication does what it's supposed to do. I don't think there's any currently active exploit out there.
As far as I know password will be sent as plain text (but encoded). So the most important thing to do is to use HTTPS protocol on login screens.
The other setting seems to be secure for me.
With HTTP Basic Authentication, which is what the .NET basic forms authentication is using, in order to view the secret.aspx page, the browser must send a Base64 encoded concatenation of the username and password.
Unless you utilize SSL, anyone who has access to scan the network between the server and the browser can read this information. They can decode the username and password. They can replay the username and password in the future to gain access to the secret.aspx page.
That said, unless you use SSL, someone can also scan the whole session of someone else using secret.aspx, so in effect, they would have access to the content of the page as well.
Well, try and look behind the scenes:
Password Protection
Applications that store user names,
passwords, and other authentication
information in a database should never
store passwords in plaintext, lest the
database be stolen or compromised. To
that end, SqlMembershipProvider
supports three storage formats
("encodings") for passwords and
password answers. The provider's
PasswordFormat property, which is
initialized from the passwordFormat
configuration attribute, determines
which format is used:
MembershipPasswordFormat.Clear, which stores passwords and password
answers in plaintext.
MembershipPasswordFormat.Hashed (the default), which stores salted
hashes generated from passwords and
password answers. The salt is a random
128-bit value generated by the .NET
Framework's RNGCryptoServiceProvider
class. Each password/password answer
pair is salted with this unique value,
and the salt is stored in the
aspnet_Membership table's PasswordSalt
field. The result of hashing the
password and the salt is stored in the
Password field. Similarly, the result
of hashing the password answer and the
salt is stored in the PasswordAnswer
field.
MembershipPasswordFormat.Encrypted,
which stores encrypted passwords and
password answers.
SqlMembershipProvider encrypts
passwords and password answers using
the symmetric encryption/decryption
key specified in the
configuration section's decryptionKey
attribute, and the encryption
algorithm specified in the
configuration section's
decryption attribute.
SqlMembershipProvider throws an
exception if it is asked to encrypt
passwords and password answers, and if
decryptionKey is set to Autogenerate.
This prevents a membership database
containing encrypted passwords and
password answers from becoming invalid
if moved to another server or another
application.
So the strength of your security (out of the box) will depend on which password protection format strategy you are using:
If you use clear text, it is obviously easier to hack into your system.
Using Encrypted on the other hand, security will depend on physical access to your machine (or at least, machine.config).
Using Hashed passwords (the default) will guarantee security depending on: a) known reversals of the hashing strategy of RNGCryptoServiceProvider class and b) access to the database to compromise the randomly generated salt.
I do not know if it is possible to use some sort of rainbow table hack into the default Hash-base system.
For more details, check out this link:
http://msdn.microsoft.com/en-us/library/aa478949.aspx
If configured correctly through the membership provider, you will have a adequate level of security. Outside of that, access to that page might be accessible through cannonical attacks, but that has to do with your general security. I gave a presentation on using the Security Enterprise Application Blocks. You might want to read up on those and look into that when implementing security on your site, and just be aware of common security threats. No site will ever be 100% unhackable, given that you are on an open shared network and total security would be an unplugged server locked in a safe guarded 24/7 by the military (around DoD "A" level security, based of Orange book). But the out of the box functionality of the Membership Providers (when configured correctly) will offer a good amount of security.
Edit: Yeah, I agree with the other comment that was made, HTTPS on at least the log in screens is a given, if you want to protect the username/passwords from packet sniffers and network monitors.
Asp.Net supports cookieless sessions, as this blog post shows. Instead of a session cookie, it uses an identifier in the url to track users.
I am not sure how secure this is, but I would think it is a secure as the difficulty to brute force the identity string.
It looks like it works more or less out of the box, however when redirecting a user and wanting to maintain session state you must include the session id. The blog post shows how to do that, as well as many other articles on the web.
Here are two good articles from Microsoft on the subject:
How To: Protect Forms Authentication in ASP.NET 2.0
INFO: Help Secure Forms Authentication by Using Secure Sockets Layer (SSL)
Cookies over URL is not secure enough, there are so many different problems with it (especially referrer leakage if you've got any) and usage of HTTPS.