Jump to content
VeiJari

Sanitize input->get()

Recommended Posts

Hello forum, this is my first security related post, so I'm a bit of a newbie.

I understand that when I have direct front-input from user I should sanitize the input, but how about when I use a secret key for showing a API for a third-party supplier? Should I sanitize the input->get() key?

I've tested this issue and I tried ?key=<?php echo $page->field; ?> And without adding any sanitization it comes back: /?key=<?php%20echo%20$page->field;%20?>

So can I rely on this, or should I still use $sanitizer just in case?

 

Thanks for the help!

Share this post


Link to post
Share on other sites
14 hours ago, VeiJari said:

I understand that when I have direct front-input from user I should sanitize the input, but how about when I use a secret key for showing a API for a third-party supplier? Should I sanitize the input->get() key?

I've tested this issue and I tried ?key=<?php echo $page->field; ?> And without adding any sanitization it comes back: /?key=<?php%20echo%20$page->field;%20?>

So can I rely on this, or should I still use $sanitizer just in case?

What you're seeing there is just what happens between browser and server, i.e. spaces getting replaced by %20. If you're echoing the value, it won't get executed as PHP code (you'd have to call eval or something similar to get that effect), but it could still allow HTML or JavaScript through – which is probably also something you don't want to allow. For an example, see what happens if you set the key value as <script>alert("hi")</script> instead.

The general rule of thumb is to always sanitize user input 🙂

That being said, if you're certain that you're only reading the GET variable and comparing it to some pre-defined value, and you'll never store or output it as-is, then there's no real harm in not sanitizing it. As you've proven yourself, it won't get evaluated as PHP code.

  • Like 3

Share this post


Link to post
Share on other sites
On 8/5/2019 at 7:34 PM, teppo said:

What you're seeing there is just what happens between browser and server, i.e. spaces getting replaced by %20. If you're echoing the value, it won't get executed as PHP code (you'd have to call eval or something similar to get that effect), but it could still allow HTML or JavaScript through – which is probably also something you don't want to allow. For an example, see what happens if you set the key value as <script>alert("hi")</script> instead.

The general rule of thumb is to always sanitize user input 🙂

That being said, if you're certain that you're only reading the GET variable and comparing it to some pre-defined value, and you'll never store or output it as-is, then there's no real harm in not sanitizing it. As you've proven yourself, it won't get evaluated as PHP code.

Thank you, it's only to compare it to a backend field that only admin's has access to.

I understand the basic principle now.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.

  • Similar Content

    • By Guy Incognito
      What's the best process for adding another user with TfaTotp 2FA? Just using it for the first time.
      Should I supply them with them with the secret when I first create their account? Seems like a security risk?
      Otherwise how do I create a 2FA user and let them login for the first time?
    • By quickjeff
      Hi Guys, 
      I have been debugging a site for the last 2 hours and cannot solve the issue. 
      I have a site running on 3.0.148. 
      I installed the Kongondo Blog module and was updating the templates to include the website style. 
      Once everything was set and done, I checked the page tree to see an error appear. 
      Template must be assigned a name before 'filename' can be accessed
      The same error appears in templates. 
      Debugging Steps
      I checked the templates in the server to ensure I didnt accidentally delete the namespace.  Deleted cache in browser and server under assets Still no go. 
      Any help is appreciated. 
      Thanks! 
    • By Spyros
      Hello
      I'm having a strange issue with the $page->find(), for some reason I'm missing some of the pages from the results. I found then that I was missing all the pages with the same "PAGE NAME". Is it a bug or am I missing something?
      PS 
      If I change the "PAGE NAME" of one of the missing ones then I'm retrieving the page without any problem.
      Thank you
    • By Guy Incognito
      This short script loops through some images from an XML feed and pushes new ones to an image field. It all works perfectly, except for some reason the last image (only) in the loop each time doesn't receive the image description... can everyone spot why? TIA! 🙂 
      foreach ($propertyImages as $img) { $fileName = trim($img[0]); if ( !empty($fileName) ) { $imgPath = '../property_data/'.$fileName; if(file_exists($imgPath) && !in_array(strtolower($fileName),$currentImages)) { $p->property_images->add($imgPath); $p->save(); $newImg = $p->property_images->last(); $newImg->description = $img[1]; $p->save(); } } }  
    • By Chris Bennett
      Plenty of posts on the forum relating to Content Security Policy (CSP) and how to integrate it with Processwire.
      It's not too hard to implement a decent htaccess CSP that will get you a solid B+ at Mozilla Observatory.
      If you're after A+ it's a little harder because of all the back-end stuff... until you realize it's surprisingly easy.
      After a lot of testing, the easiest way I found was to specify only what is needed in the htaccess and then add your required CSP as a meta in your page template.
      Plenty of people have suggested similar. Works very easily for back-end vs front-end, but gets complicated if you want front page editing.
      Luckily, a little php will preserve back-end and front page editing capabilities while allowing you to lock down the site for anyone not logged in. 
      None of this is rocket science, but CSPs are a bit of a pain the rear, so the easier the better, I reckon 😉
      The only CSP I'd suggest you include in your site htaccess is:
      Header set Content-Security-Policy "frame-ancestors 'self'" The reason for this is you can't set "frame-ancestors" via meta tags.
      In addition, you can only make your CSP more restrictive using meta tags, not less, so leaving the back-end free is a solid plan to avoid frustration.
      Then in your public front-facing page template/s, add your desired Content Security Policy as a meta tag.
      Please note: your CSP should be the first meta tag after your <head>.

      For example:
       
      <!DOCTYPE html> <html> <head> <meta http-equiv="Content-Security-Policy" content="Your CSP goes here"> <!-- followed by whatever your normal meta tags are --> <meta charset="utf-8"> <meta name="viewport" content="width=device-width, initial-scale=1"> <meta name="format-detection" content="telephone=no"> If you haven't got Front Page Editing enabled, this works fine by itself.
      Just one extra step is needed to make sure you don't have to worry either way. 
      The easiest way I found to allow both CSP and front page editing capabilities is the addition of a little php, according to whatever your needs are.
      Basically, if the user is a guest, throw in your CSP, if they're not do nothing.
      It's so simple I could have kicked myself when it finally dawned on me.
      I wish it had clicked for me earlier in my testing, but it didn't so I'm here to try to save some other person a little time.
      Example:
      <!DOCTYPE html> <html> <head> <?php if ($user->isGuest()): ?> <meta http-equiv="Content-Security-Policy" content="Your CSP goes here"> <?php endif; ?> <!-- followed by whatever your normal meta tags are --> <meta charset="utf-8"> <meta name="viewport" content="width=device-width, initial-scale=1"> <meta name="format-detection" content="telephone=no">  
      If you want it a bit more involved then you can add additional tests and be as specific as you like about what pages should get which CSP.
      For example, the following is what I use to expand the scope of the CSP only for my "map" page:
      <?php $loadMap = $page->name === "map"; ?> <!DOCTYPE html> <html> <head> <?php if ($user->isGuest()): ?> <meta http-equiv="Content-Security-Policy" content="default-src 'none'; base-uri 'self'; manifest-src 'self'; form-action 'self'; font-src 'self' data: https://fonts.gstatic.com; frame-src 'self' https://www.youtube.com; img-src 'self' data:<?php echo ($loadMap) ? " https://maps.googleapis.com https://maps.gstatic.com" : ""; ?> https://www.google-analytics.com; script-src 'self' <?php echo ($loadMap) ? "https://maps.googleapis.com " : ""; ?>https://www.google-analytics.com https://www.googletagmanager.com; style-src 'self' <?php echo ($loadMap) ? "'unsafe-inline' https://fonts.googleapis.com" : ""; ?>"> <?php endif; ?>  Hope this saves someone a little time testing.
      https://observatory.mozilla.org/analyze/bene.net.au
×
×
  • Create New...