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Author seems self-righteous and does not understand what he is being told by Ben from Sendy. This is additionally evidenced by hundreds of lines of email and a blog post for what could be addressed with 12 lines of code modification.

Sendy is open source (albeit not free) and running on your own server. Ben's response says because you are using a customized webform instead of sendy's provided forms, that you need to handle the captcha code on the form and siteverify on the backend on your own.

Before sendy had recaptcha support you would have to modify the subscribe code to include a call to captcha siteverify. Here's some PHP code for how you call siteverify before proceeding with something: https://www.adam-bray.com/2018/04/02/adding-recaptcha-with-p...

You can avoid running your own backend altogether now anyway since SES supports bulk template emails. You can store all your form submissions using a lambda/cloudfunction/webworker to verify the captcha and store the list. When you want to send email you can pull your list into something running on your laptop and then invoke the SES bulk templated email from there. You can use lambdas for pixels and custom links that update records for those users. I wrote my own angular-firebase version of this






My reading of the issue is that Sendy's webform allows the external requester to bypass the server-side captcha logic by changing a client-side "hidden" input. If you want to be protected then you have to customize the form.

I have the source code too and checked it already. The gist of the code is:

if subform:

   if captcha fails:

       feedback = "Failed recaptcha test"
... if feedback!='Failed recaptcha test' (&& other stuff)

   do subscribe

edit: misread the code and formatting on HN didn't even show my intent, but the subform check doesn't contain the subscribe logic. The bug is clearly that it doesn't check if the captcha has passed.

And the point is that anyone with even a modicum of dev experience can remove the `subform` field and automate submission to the otherwise-standard form and completely bypass ReCAPTCHA.

The issue goes even deeper: if subform is set to no then sendy considers the user as added via api. This should mean that it would verify_api_key before allowing such a submission, but sendy doesn't verify the API key for subscribe calls (doh!). Old forum posts suggest that double-opt-in is a solution, however not only can you bypass the captcha and form with subform=no, you can also bypass double-opt-in via the subscribe API by sending silent=true in your POST.

Here's the diff for subscribe.php to require captcha for all list adds: https://pastebin.com/tSLkvYME

if you need API support, you could use captcha_passed = verify_api_key($api_key) and include the api_key in the post request


> Sendy is open source

According to what or who? It ships with laughably obfuscated files, it makes no mention of open source in any documentation.


> Sendy is open source (albeit not free) and running on your own server.

How does that work? What's the license exactly?


It's not:

> This Agreement grants a non-exclusive, non-transferable license to install and use the Software on a single Website. Additional Software licenses must be purchased in order to install and use the Software on additional Websites. The Author reserves the right to determine whether use of the Software qualifies under this Agreement. The Author owns all rights, title and interest to the Software (including all intellectual property rights) and reserves all rights to the Software that are not expressly granted in this Agreement.

> [...] You may not:

> Distribute derivative works based on the Software;

> Reproduce the Software except as described in this Agreement;

OP might mean source accessible (rather than compiled or being a hosted service).

https://sendy.co/end-user-license-agreement




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