How to add assign csrf token in the HTML submit form

Question

My site is under csurf protection at the moment.

I have assigned all my ajax call with csrf token like below

"/data/someAPI?_csrf="+ $("#_csrf").val and it works just fine with all function I had.

But now I am writing a file upload function and most of the tutorials on the internet are using sumbit form to do so.

So I wrote something like

Node.js

app.post('/upload', function(req, res) {
  if (!req.files)
    return res.status(400).send('No files were uploaded.');

  // The name of the input field (i.e. "sampleFile") is used to retrieve the uploaded file
  let sampleFile = req.files.sampleFile;

  // Use the mv() method to place the file somewhere on your server
  sampleFile.mv('/somewhere/on/your/server/filename.jpg', function(err) {
    if (err)
      return res.status(500).send(err);

    res.send('File uploaded!');
  });
});

Solved

HTML

<html>
  <body>
    <form ref='uploadForm' 
      id='uploadForm' 
      action='http://localhost:8000/upload?_csrf=<your_csrf_token>"' 
      method='post' 
      encType="multipart/form-data">
        <input type="file" name="sampleFile" />
        <input type='submit' value='Upload!' />
    </form>     
  </body>
</html>

I directly assigned the token in the form action and it works fine.

Why not do it as you are doing in ajax call? i.e. define token in form action. — aquaman
– aquaman, Commented Nov 28, 2017 at 8:45
@aquaman do you mean i should <input type='hidden' name='form-control' value='{{_csrf}}'> put this line within the form? — Anson Aştepta
– Anson Aştepta, Commented Nov 28, 2017 at 8:49
I meant modify your form as action="/upload?_csrf=<your_csrf_token>". And well what you suggested in another option you can try. — aquaman
– aquaman, Commented Nov 28, 2017 at 8:51
Quick question, how do you obtain that CSRF token in the first place? — Joshua M. Moore
– Joshua M. Moore, Commented Oct 23, 2018 at 19:48

carlo318 · Accepted Answer · 2024-08-14 13:53:58Z

4

You can add hidden field for _csrf token. Here is example code

<html>
  <body>
    <form ref="uploadForm" 
      id="uploadForm" 
      action="http://localhost:8000/upload" 
      method="post" 
      encType="multipart/form-data">
        <input type="file" name="sampleFile"/>
        <input type="hidden" name="_csrf" value="<your_csrf_token>"/>
        <input type="submit" value="Upload!"/>
    </form>     
  </body>
</html>

edited Aug 14, 2024 at 13:53

carlo318

512 silver badges10 bronze badges

answered Nov 28, 2017 at 10:06

Bhavin Solanki

4,8143 gold badges28 silver badges47 bronze badges

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1 Comment

Rudra21 Over a year ago

@BhavaniSolanki : After implementing CSRF solution hidden field comparing server side , the problem is , when open new tab with same URL then hidden filed comes null.Server side condition is if CSRF hidden field null then its attack.is it expected behavior ?

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