Is there a way to only let a webpage be viewed if the link pointing to it is pressed. I am sending emails to members of my organization with links that attach values to the URL so I can use phps $_GET to figure out who they are on the webpage and update appropriately. What I am worried about is individuals changing the values of the link and changing other members data. If there is a better method for doing this, I am all ears. Using a log in system is not an option.
Not exactly, no.
What you could do is include some token that you keep associated with a particular user id and is very difficult to guess, and include that in the link as well - then, when you get a GET request, you check to make sure the token matches the one you know is correct for that userid. (You'd store the "correct" tokens locally in a database when sending out the emails.)
For instance, you might have...
/modify_info_script?user_id=123&token=aSDqWEqwejk2123salskq
And then you'd have a database table or some other storage that has...
user_id token
----------------------
... ...
122 klqwkejajwie8u8213nak
123 aSDqWEqwejk2123salskq
... ...
and thus if someone tried to change the user_id in the URL, the token wouldn't match and you could reject their request. For instance, this would get rejected...
/modify_info_script?user_id=122&token=aSDqWEqwejk2123salskq
since the right token for 122 would be klqwkejajwie8u8213nak, not aSDqWEqwejk2123salskq.
This is probably the best option if using a login system isn't an option. However, you should really make sure that using a login system isn't an option at all, because user data really should be protected by a login.
This is really not the proper way to secure your site.
However, the simple fix for you is to check the "referer" header and make sure it's not blank. If it's not blank, then it came from a click (or they spoofed it, which is why this isn't secure).
The real way to protect data is to implement a login system with a set of permissions.
To check, if someone came from a link, see $_SERVER['HTTP_REFERER'].
To protect the application against link manipulation, you can combine it with a secret passphrase (only internally, the passphrase must not be known to anyone) and use md5() on the result. Attach the MD5 to the url. If anyone manipulates the url, you will know because the MD5 of "the url plus your passphrase minus the MD5" will be different.
Quite a lot password reset systems work like this so you could say it's reasonably safe provided you use long enough random token. Something like 32 chars should be fine.
Just providing the token should be enough since you don't need the user ID to check it against issued tokens in database.
/modify_info_script?token=aSDqWEqwejk2123salskqfilltill32chars
The other alternative is to have login system where use has to type in their credentials in order to change information.
Also if you really fear that someone might try to guess it, just timeout/ban users after 3 wrong token attempts. No one should be trying to type them in by hand anyway.
Related
I have a question that is more conceptual at the moment than anything else.
Here's my situation
The school that I go to has a website for grade viewing which can be found at this link: https://grades.bsd405.org/Pinnacle/Gradebook/InternetViewer/Default.aspx
The login page presents a username and password box.
I plan on constructing a simple iPhone app that takes the resultant grades that are listed and display them in a UITableView.
However, how would I achieve getting the data from this website?
How do websites validate (authenticate) usernames and passwords and then pass on the relevant data?
Thanks for bearing through this tough question.
There are a lot of things going on in this website; i think we would need a little more info from you on your specific request. When you say Validate, do you mean validate as in check that usernames and passwords are formatted correctly or do you mean validate as in authenticate, i.e. send the resultant data to the X to determine that the username and password is correct.
Based on what I see I can partially answer your question, the asp site would send over SSL, the user name and password to the application, where I would assume the application then checks the username and password against a username and hash of the password (the hash being the calculated squish of the password which is stored as such for security and confidentiality).
In your case you wouldn't need to know any of that if you wanted to interface/integrate an app with this, you'd just need to format a request in your app and deliver it over an SSL connnection to the page. There's a caveat; and that being session stuff with ASP; its a bit more complex than just usernames and passwords.
The page generate a unique ID each time, passed as hidden field of the form. So i'm sorry but i think that you can't post nothing from the extern.
Yes, you certain can pass the hidden id.
What you need to do is follow the session stuff that ASP generates. We do this all the time with ASP sites that we 'scrape' for data with our primary application.
Your app will first need to call the site, collect the sessionid data, and return that in your form when you submit the form for authentication. After that depending on what is happening in the site, you may need to capture and send the resultant sessionid on each subsequent request.
Actually its a horrible thing when you see how much useless data is passed back and forth by ASP.
I have a PHP project is essentially an order processing website for a company. Each user in the company has access to this website and is given certain credentials to the application that control access to pages and functionality throughout.
Now I have a request to allow a guest access to a single page. The complexity of this request is that the guest will be different each time as well as the page will be different. Basically it is a portal to allow customers, who don't have accounts within the system as there is no live ordering on this site, to be able to access and verify the order and shipping information.
My thought to accomplish this is to have a database table setup as a guest relationship table that will be used to store UIDs, MD5 Hash Keys and the destination page that the record is referring to. Also included would be a visit counter and expiration date. When the user receives an email they would have a link provided in the email to somewhere like http://website.com/verify/?HASH-KEY.
When this link is clicked I expect that the verify index.php page takes in the HASH, verifies it in the database and displays the page reference in the database within this location instead of redirecting into the application. This would allow guest access to the single page without the need to expose the structure of the website or a rework of the user authorization already setup.
Am I approaching this solution in the proper manner?
How do I grab the contents of one page and display it in another?
1. Am I approaching this solution in the proper manner?
Yep, more or less.
Some pointers:
Make sure you seed hash generation randomly. For example, DON'T simply MD5 a customer ID or some other small/sequential number, as that would make it easy for a malicious use to hunt down other pages.
Expire the hashed links after a set time out.
2. How do I grab the contents of one page and display it in another?
If you want people to "access and verify the order and shipping information" you should probably create a page specifically for it, instead of trying to pass through normally secure pages to insecure guests. Ie, a 'shipping confirmation page' that populates details according the data keyed by the supplied hash.
I'm trying to a follow this as well as I can.
It seems to be you should use your hash method, and just have a stand alone page that will generate the content you want, totally separate from the rest of the system. Just put enough data in your hash URL to determine what is needed.
Something else to do is use a timestamp in your hash string URL and have that timestamp part of the random bits that you generate your hash on. This will allow you to make a URL essentially "expire" after a certain point.
Example: url.com/in/123456789865/hash-here
You can compare "123456789865" in this example to the current server time and determine if its expired. Of course you need to make "123456789865" part of your hash encryption to still validate
If I understand you correctly (and I think I do), than I think you're approaching this correctly.
To include another page's contents, you usually use include.
include "/path/to/page.php";
How Do i secure vote buttons in server-side like here on Stackoverflow? I've seen how the button can be submitted in this answer, But how about in the server side, how do I protect the voting system from csrf attacks and such?
bots generally doesn't run javascript, so just check on server side if it was an AJAX call.
If you want to be more protected maybe append a param generated automatically by javascript with some calc based on current time, then check on your server if it's match with the same calc
A widely accepted way to protect from CSRF is to use a nonce. When the button is clicked and a request is submitted via AJAX or POST data, a nonce value is passed along with it. That nonce is then verified on the backend. You can have that nonce value stored in the session upon generation, possibly using hashing / salting so that the nonce can be specific to a certain action, ie 'vote-up', 'vote-down', etc.
See:
need help understanding nonce
Put a unique id in the GET query portion of each arrow link. That way the attacker / spoofer cannot know to which address to direct the CSRF attack.
The easiest and most effective way is probably to require all users who desire to vote to signup, so that you can keep track of who is voting on each post. As soon as you know who every voter is, you save the user id along with every vote, then you can easily validate that the users hasn't previously voted on a specific question.
Then of course you have to protect your sign up form, to make sure that bots can't register, but that can be done using reCAPTCHA and other similar methods. You will probably also try to limit the users from registering for more than one account. That is of course tricky, but you can at least start of by requiring unique email-addresses for every account, or make use of some third part authentication like Google, Facebook etc.
If you don't want to require sign up, then I guess you have to fallback on registering the IP-address of every vote, but going down that road is trickier. Bots will probably use a whole range of IP-addresses, and you might ending up blocking votes from different users who happens to share the same IP - which can be really annoying.
You can require a Login and even use openid for that.
I've been asked to leave passwords and user names aside since most of the site visitors are stop-buy-come-back-several-months-later-kind of visitors, and the motivation was somewhat along the lines "they would forget there passwords any way and have to request new ones".
I suspect there is no realistic way for me to do this thinking IP:s probably change and browsers get updated, cookies are cleared and so forth.
Or do I have any options?
(not that I'm looking for code but rather concepts and pseudo but the language in the project is php/js coupled with an apache server)
Use OpenID.
Let Facebook, Google, Wordpress, or even Stack Exchange handle the authentication for you, and people wont have to remember another password.
Alternatively:
Many users understand the "forgot my password; check my email" routine by now, so why not just short-cut it by having them input their email and send them a login url with a randomly generated token to log in with.
Once they're logged in, keep them logged in for as long as you deem secure.
We do the following in our e-commerce solution:
We use email as a unique identifier.
When a customer makes a purchase using the same email, the order will be attached to their existing user. You don't however get any address details or stuff like that, but have to enter it manually.
The customer will receive an email with a generated password if it is a first time buy. If it is a second time buy, they will just be instructed to log in. This can however be combined with a url and a login token. Likewise for logging into the site, you could just have them enter an email to receieve a login url token.
Combine this with a long living cookie and/or the browsers datastorage to remember the customers details (address and stuff like that).
Another option would be to have them entering something about themselves that they would always know, but others wouldn't. However it is hard to have an internationally workable solution for this.
You could use so-called supercookies, which is offline storage on the client side. Either through html5 offline storage, or plugin like flash to restore deleted cookies. Although, these cookies is likely to be banned at some point, since they're mostly hidden for the user, and very hard to get rid of. (Not recommending this approach, just saying it's possible)
Authentication credentials break down to three options;
Something you know - passwords
Something you have - physical keys, cards
Something you are - iris, retinal and other biometrics
The best you can do is use cookies I think. Or...I guess you could have them download a file, and upload that file as their access credential - same idea as a cookie but unlikely to be deleted. You would have to think carefully about what to put into the file however - their user id isn't enough, as it would be easily hacked. A random long string would do, one that is saved into the database on their account. Nothing that can be predicted, and nothing that can be used to guess a different account's credential.
A couple of options come to mind:
Use a persistent cookie, but only do this in conjunction with SSL (so it simply can't be sniffed off the wire)
Another option is OpenID like you use here - therefore vistors can use an account they use often to log into your site.
It seems to me that your only option is giving them a forever cookie and hoping it doesn't get purged between visits.
You can read about them here.
I have
echo <a href=\"javascript:;\" onClick=\"window.open('". $link ."','no','scrollbars=yes,width=550,height=400')\" >View report</a>
$link contains sensitive information, so I'm wondering if there is a simple way to prevent this link showing up explicitly when you "view source code" on the browser. Any alternative to href would be fine. I just need to give the user an option to click and see his processing result after he submits some data. I would like to avoid having auto popups as soon as the processing is submitted.
UPDATE: so the $link is a GET URL that includes a user ID and password.. It's internal right now so it's fine, but I'm thinking of putting this on our online server in the future. I'm very much a novice with PHP, so this is probably not in the near future as I don't know much about security features that need to be implemented for a live site on the Internet. Right now, it seems that utilizing a database would be the best way to go. Correct me if I'm wrong, please, and thanks for all of the support!
If the user has to navigate to the link, there is no way to actually hide the information. You should rethink how your process works so sensitive information is not displayed in the link.
Perhaps you can store the information in a database table and the link would just use the id of the row that has the information.
Simply put: No. If you send me to a URL, I will be able to see it using some sort of tool. Wireshark, Fiddler, etc. Consider using a different link structure.
If the user already owns a session, this is an option:
If you render a page and need to protect this given sample secret URL
http://www.MyHost.com/?what?secret&id=23232
save the URL in the user's session and associate a hash value with the secret URL.
Instead of sending the URL to the result HTML-page, insert another URL, e.g.
http://www.MyHost.com/?continueWith=<hashValue>
If this URL gets called, check the user's session and retrieve and delete the secret URL. Then continue to evaluate, as if the user had called the secret URL.
This way, no parameter of the original secret URL ever reaches the user's browser.
To refine the schema, attach a lifetime to the URL saved in the session. If a request comes later as the end of life, return an error.
If you protect all URL in such a way, users won't be able to call arbitrary URLs, since all acceptable URLs are those inside their sessions. Thus, a user will even not be able to change parameters of less secret URLs.
How is $link generated in the first place? If it is sensitive, this implies that the user has already been authenticated somehow. Thus, the information in $link can be stored in the session where it's safe
Save all the information in your PHP session (or preferably the session system your PHP framework uses) and then just send some kind of non-db-associated identifier in the link so that the code knows what you want to do next.
For example you could have a link to "http://www.yourdomain.com/sec/special_action/4" with "sec" meaning secure, "special_action" being the name of the action to take, and "4" being the action id reference.
So lets say you have to have it associated to their social security number. Then you would in your back end use a salted hash to encrypt the SSN and save it to the session data. You then append it to the end of your session array and get an array count. If it returns 5 then you know that the encrypted SSN is saved in index 4 (since PHP uses 0 based indexing). So you send along that index as part of the link to confuse things even more. Heck you can even salt and hash the index if you want.
The user clicks on the link, the code finds the index, grabs the encrypted content, decrypts it, then uses it. Easy and secure.