I know that man in the middle (mitm) can be in passive mode : forward, or active mode : modify trafic and forward...
But Can mitm open a page, in firefox for example, to connect on a website where i was logged.
Is this possible ?
Yes, as you say, the man-in-the-middle can modify the traffic. So when you request a page, he/she can easily return an HTTP 302 to another page, or insert some JavaScript to set the document.location.href of your document.
If your traffic is encrypted using https, this is not possible.
Related
I have a trivial question about web architecture. When I build a web service/application, I want to make it only work perfectly on https protocol.
Firstly I analyzed the google's methodology by network session of chrome developer tools. In there I found it, when a http request is sended to the google, that the request redirected to https of same origin.
I thought it is a respectable way. But I find it has a potential risk. When an authorized user using the google, he have a session. And after, he want to deep another site (e.g. Yahoo). And he will come back to the google by inserting the address 'google.com' directly in browser's address box. In this situation if the user didn't shut off the google session, in the redirect process, the unencrypted session token will be sended to google because the redirect process be proceeded on http protocol. So this user will be exposed MITM(man in the middle) attack.
So I hesitate to use google methodology. Anyone have a idea?
Set the secure flag on the session cookie. Then it won't ever be sent over HTTP.
This is a question about the functionality of htaccess password remembering. When i visit a htaccess protected website and enter my password i can visit the site without entering the password again until i change my ip address. I first thought my browser would save the password but that can't be the case because the browser shouldn't care about ip changing, right? The only option left would be that the webserver saves my ip address. But then would whoever would get my ip address after me be able to access the site without entering the password, that wouldn't be save.
Do you know who remembers my htaccess password?
The authentication method is known as Basic Auth.
As you can read from the article, the Browser has to send the credentials with EVERY request, so there is no session or similar whatsoever on the server-side.
The browser will 'remember' for a while (differs from browser to browser). I suppose it's either a coincidence that you get "logged off" whenever you change your IP, or your browser detects the connection loss and clears all cached credentials.
tl;dr: the browser
It is the browser.
But the browser is sensitive to changes.
One of customers have reported that they can see the password being transferred as clear text, they probably tried tool like a fiddler to capture the HTTP request/response. So my question is is it possible using fiddler or any other tool is it possible for someone to monitor the http traffic on that local computer at the moment the user entered the password and clicked to login ?
If the user is accessing the website without using SSL (i.e. by going to "http://" instead of "https://"), then it is possible to see all of the traffic between the website and the browser, and not only on the local computer but also on the network that the computer is connected to.
If the user is accessing the website via HTTPS, Fiddler is able to act as a proxy and decrypt the traffic between the browser and the server by using a special SSL certificate (thanks to #user18044 for clarification in the comments below).
In your case Fiddler is NOT accessing browser memory directly to get to the password in clear text.
HTTPS is slow to start up, especially on low-bandwidth and high-latency connections, or on low-spec machines. Unfortunately it seems to be the standard method for securing logins used by all major websites.
But a lot of websites we usually visit simply to read information. If we only occasionally want to make a write/update, then waiting to get logged in is an unnecessary time overhead.
The most upsetting example for me is:
Github. I often want to visit a github page just to read a project's overview or view a file. But I must wait for the SSL handshake, even if I don't want to do anything related to my personal account. Github always redirects my browser from HTTP to HTTPS. Why?!
I understand a secure connection is important to authenticate a user account. But when this impacts the user experience of simply viewing public pages, we should try to work out an alternative (and encourage major sites to adopt it).
Here is a possible workaround (1):
Allow users to make HTTP connections to our website, so we can present pages quickly without the need for an SSL handshake.
Allow the login to occur after the page has loaded. Perhaps an Ajax request over HTTPS could authenticate the user, and provide relevant updates to the page. (Is this fundamentally insecure? Edit: Yes, it is not fully secure, see answer below.)
Another alternative might be (2):
Instead of long-lived cookies over HTTPS, use a combination of long-lived one-time-key cookies for persistent login, and short-lived cookies for non-linear browsing, over HTTP. Replace them frequently. (This may be less secure than HTTPS, but more secure than normal long-lived cookie usage over HTTP.)
Do these solutions seem secure enough, or can you suggest something better?
(It might not be a coincidence that I am writing this from somewhere near Indonesia, which is a long way from the USA net!)
Workaround #1 in the question cannot provide full security to the first page, because a man-in-the-middle attack could have injected or modified scripts on the page before the login occurs.
Therefore we should not ask for a username/password on the HTTP page. However, the HTTPS Ajax operation might be able to inform the user that a persistent login session has/can be restored. (A script could then replace all HTTP links on the page with HTTPS links.)
But even if that succeeds, we still should not fully trust any user clicks or <form> POSTs originating from the first page. (Of course, requests to view other pages are fine, but it might be wise to reject updates to settings, password, and finance-related actions.)
This technique could at least be a way to perform the HTTPS setup in the background, without making the user wait for initial content. (StackOverflow uses something like this procedure.) Hopefully the browser will cache the HTTPS connection, or at least the keys, avoiding any delay on subsequent requests.
Here is one alternative I can think of, albeit slightly restrictive:
Allow browsing of public pages over HTTP, but don't perform any user login. This avoids all security concerns.
The 'Login' link would then send us to an HTTPS page, and may be able to recover the user's account automatically from a long-lived HTTPS cookie.
Make an option available "Always log me in through HTTPS", for users who are not bothered by the handshake overhead, and prefer to be logged in at all times. Note that a cookie for this setting would need to be set on the HTTP domain, since it needs to work without the user being logged in!
In reality, we would probably offer the converse: default to the existing prevalent behaviour of redirecting to HTTPS automatically, but provide an opt-out "Do not always switch to HTTPS for login" for those users wishing to avoid the SSL handshake.
But there are still issues with this approach:
Unfortunately cookies are not namespaced to the protocol (http/https). We can mark cookies as "secure" to prevent them ever being sent over HTTP, but some browsers will wipe them entirely if an HTTP request does occur. One way to keep the cookies separate would be to use different domains for unauthenticated and authenticated access to the site. But then we find ourselves violating REST, with two different addresses pointing to essentially the same resource...
Can this be resolved?
On my website users can post stuff anonymously.
When they have posted something they will be redirected to their post, let's say:
http://example.com/post/2/title-of-the-anonymous-post
The user who submitted the post and the admins are the only ones with access to that post (until it is made public). Once it is made public the post would still be anonymous (i.e. people cannot see who submitted the post).
However, on that page there are also some external links. If the user decides to click an external link the target website has the ability to log the http referer (which would contain the link to the hidden page). This means it would be possible to find out who posted it once it is made public.
Is there a way to change the HTTP referer (/ referrer) when a users clicks on a link to another website?
By for example first redirecting the user to another url and let that page redirect to the external website:
user clicks on: http://example.com/referer-hider?url={urlencoded(url)}
and let the referer-hider redirect the user to the external page so that the referer will contain: http://example.com/referer-hider?url={urlencoded(url)}
Will this work? Or is there another solution for this (which doesn't require client side modifications)?
Since the referrer is provided by the browser to a web server, I only see two ways to insure that external sites don't get a view of this "hidden" URL.
First way would be (as you said) to remove the external links from your hidden page by running them through a redirector which uses header("location: ...");). Yes, that will work. You might just want to use this in general, so that you can track the exits from your site.
Second way would be to stop hiding this URL. It won't stay hidden forever, after all. A Google/Alexa/whatever toolbar hits it, and bam, it's indexed. So instead, build this hidden functionality into something session based. Make a script that changes its output depending on session variables, and only allow the hidden content to show up if people have logged in or previewed their post or whatever.
The third (and probably best) way would be to implement proper access control, so that anonymous users CANNOT visit the page with the restricted content. If you want an anonymous original poster to be able to visit THEIR OWN post, you can send them a cookie, then validate the cookie upon the visit to the unapproved post.
For example, upon submission for approval:
setcookie('postkey', mysql_insert_id());
Then:
$pieces=explode($_SERVER['PHP_SELF']);
$postid=$pieces[2]; // or whatever
if (!isset($_COOKIE['postkey'])) {
header("Location: http://example.org/");
} else if ($_COOKIE['postkey'] != $postid) {
header("Location: http://example.org/");
}
etc. You probably want better protection than this, but it should give you some ideas.
The HTTP referer is not transmitted by the browser when a link is going from HTTPS->HTTP. So a simple solution is to have an https redirect page: https://yoursite/redirect?url=... . However this page is also vulnerable to OWASP a10 - Unvalidated Redirects and Forwards, but that might not matter to you. Another solution that doesn't expose you to OWASP a10 is to use a free redirect service.
The Meta referrer proposal from Adam Barth would help with your case; in short you could tell browsers via a <meta> tag that the Referer header should be stripped on all outgoing links.
This isn't a complete answer since it's only implemented in Webkit thus far, but it's something to keep an eye on.