Security: Passing payment amount to PayPal - security

From what I understand, using the PayPal api, you can pass your payment amount by populating a hidden HTML input field which will be submitted to PayPal.
What I've got so far looks somewhat like this:
<input type="hidden" name="amount" value="60.00">
My question is - isn't this super unsafe? What's there to stop someone from changing the payment value in the element inspector for instance?

You may want to use PayPal ButtonManager API operation in order to programatically create, manage, edit, and delete PayPal Payment Standard buttons, which are the same kind of buttons that you can create from the PayPal Profile.
Hosted buttons created by this API reside on PayPal and can use all features, including inventory management; however, you can use this API to create code for non-hosted Standard buttons as well.
The button you will create from this API request will look like:
https://www.sandbox.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=19218
As you can see no values like "business", "amount" or others are visible and for this reason this would be a safe solution and personally I'd recommend it.
Back to your question "What's there to stop someone from changing the payment value in the element inspector for instance?"
We recommend to use API requests (see ExpressCheckout or ButtonManager to create Standard buttons) and Instant Payment Notifications service (IPN), which is a message service that notifies you of events related to PayPal transactions. You can use IPN messages to automate back-office and administrative functions, such as fulfilling orders, tracking customers, and providing status and other transaction-related information.

Related

Is it okay to have a bunch of incomplete Stripe payment intents?

I am implementing the Stripe payment platform using JavaScript and the PHP SDK.
I don't have any issues with the implementation itself, but I am not sure whether I have to reuse an existing PaymentIntent or it's perfectly fine to have a bunch of them created and incomplete.
I searched for this in Stripe's documentation, but I can't seem to find anything related to this.
For example, in my test account I have this:
It's all for the same transaction, because I was changing some visuals and refreshing the browser.
I am aware that each PaymentIntent has an ID, but is it recommended to add it as a query parameter and retrieve it on refreshing, or is it better to always generate a new Payment Intent.
My main reasoning is to avoid having a huge collection of incomplete payment intents.
The default integration path for Stripe today is to create a PaymentIntent first so that you get a client_secret you can use client-side to render their UI via PaymentElement. This means that if your customers decide not to pay after all, you end up with an incomplete PaymentIntent which is expected.
This is not really a problem, other than appearing in the Payments list which can be confusing. You could also write a background job daily that would cancel any PaymentIntent via you know won't be completed because the customer left and you didn't have any data to contact them to upsell them for example but this isn't really needed.
Stripe also has a beta (docs) right now (Feb 2023) that changes the default integration path. This simplifies the experience because you can render the PaymentElement client-side with specific options such as amount and currency. You'd then only create the PaymentIntent at the end of the flow
when the customer is attempting to pay. That flow limits the number of incomplete PaymentIntents since you only create them when the customer really pays. You'd still get some, for example after a decline by the customer's bank though.

Best way to handle one-time payments with STRIPE webhooks in nodeJS

I am using STRIPE as my payment processor, in an REACT + nodeJS app. I already have something that already works, but I would like some feedback, maybe I'm doing something wrong.
So... I have this Redirect-To-Checkout functionality thats made available by STRIPE, basically I redirect the user to this STRIPE page where all card-data (sensitive information) is processes in order for the payment to full-fill.
What I do in my nodeJS server part is the following:
Once the user acces the redirect to check-out page, I already create a PendingOrder, with the products selected by client (Here I save some information based on client/stripe payment-intent, in order to check in later steps)
Once webhook gives me the 'payment_intent.succeeded' I check for the payment-intent information to see if it exists in my PendingOrder collection, then proceed to add in to ConfirmedOrders and remove it from PendingOrders.
I have to do this whole process because Stripe no longer gives me access to some information I require when the user is checking-out his order(such as observation that the user has based on the type of service he chooses).
Are there any down-sides to this approach or is there any other way to do it?
Thanks in advance!
You’re not really far from the best practices that Stripe recommends here. The only thing that I would change is listening to checkout.session.completed instead of the payment_intent.succeeded event. As of the latest API version, a PaymentIntent is no longer created upfront so a better to way to handle order fulfillment is to either store the Checkout Session ID (e.g. cs_live_xxx) or you could add some metadata when creating the Checkout Session and use that instead to identify the order.
I have to do this whole process because Stripe no longer gives me access to some information I require when the user is checking-out his order
As for this, I’m not sure what you mean, you can always use your app with the success page customization described here alongside webhooks. I wouldn’t use that to fulfill the order though since the user might close the page before the redirection completes which means that the fulfillment wouldn’t be done in that case. As such, webhooks are essential to order fulfillment.

Stripe API testing automation

Background
I am integrating stripe API into my site to take one off payments. My site will be API first on server side with a separate web and mobile front end. I am working on the API server side code. I will eventually use stripe payment pages to take credit card payments. I am trying to automate the testing of my APIs and am bamboozled by the documentation (which are thorough) as I just can't see what steps to take next.
My server side initiates a call with stripe using stripe sdk to create a stripe Session object - this contains a URL to redirect to checkout.stripe.com/pay/..., a success URL when payment is successful and a cancel URL (these I set to handle the callback).
Problem
I can automate in Postman all my API calls from Browse Products, Select Product, Place Order but the next step I am stuck. After Placing Order I get back the stripe session but how can I mimick making the payment with stripe for the session and then call my Success URL ?
When the site is complete I will redirect the UI to stripe to take payments but I am testing and completing the back end flow first.
I have copied and pasted the session URL which is returned by the stripe Session object to bring up the page in a browser and used Dev tools on Chrome to inspect Network to see which APIs are being called by stripe in an attempt to reproduce and I can see a POST to stripe.com/api/payment_methods and I can see the posted values but I can't reproduce this in Postman. Also, the documentation (https://stripe.com/docs/api/payment_methods/create) says
"Instead of creating a PaymentMethod directly, we recommend using the
PaymentsIntents API to accept a payment immediately"
Question
Which stripe APIs do I need to call to automate the flow from a stripe Session object to make a payment and then check that it was successful? Payment Methods? Make a Charge? Payments Intents? ...and how. Happy to be pointed to the documentation if you can help me understand the flow.
TIA
Checkout is a Stripe product that looks like a "box" and you can't know (and shouldn't need to know) what happens inside. It is created for the purpose that merchants won't have to think about what's being done under the hood.
Speaking from an automation perspective, you can try to reproduce the whole process but there's no guarantee it won't change in the future, and it could leave you with more problems later.
For options to reproduce:
The closest way is simulating browser filling and submission, using automated browser tools (ie Selenium). But it's not as straightforward as PostMan. Generally you would want to simulate every browser action that a human could do.
Or you can try to accomplish the same with the logs and events you receive on Stripe's Dashboard, when you test a Checkout Session by yourself. From now there are 3 requests.
And your goal is to receive the same 5 events in Webhook:
TBH I recommend to reconsider the need of this test, to see if it worth your efforts.

Can I redirect customer back to my store from Stripe Hosted Invoice page?

I'm generating Invoice object in Stripe and then redirecting customer to the hosted_invoice_url (https://stripe.com/docs/api/invoices/object#invoice_object-hosted_invoice_url)
After customer completes the payment, in the final step they are presented with two buttons - Download Invoice and Download Receipt, but there is no button/link for going back to my store. So it's a dead end. Customer can only close their browser tab.
Is there a way to specify something like success_url or home_url that would add a button for getting the customer back to my store?
Right now as a workaround I'm forcing hosted_invoice_url to open in a new tab. Customer closes the tab after they are finished and they get back to my store in the original tab.
From what I know, this is not possible with hosted invoices pages. I'd recommend relaying this use case/feedback directly to Stripe.
However, if you were to use Stripe Checkout you can pass success_url and cancel_url parameters which will fulfil your requirements in this case. Perhaps Checkout might be a better product for your use case?

Creating new payment method for Bigcommerce

I would like to know if this is possible to add new payment method for Bigcommerce. I tried to contact their support without any luck. If anyone is familiar with bigcommerce and know if this is possible, i would appreciate any advice.
I already read their API docs and didn't found anything useful - only method to obtain list of available payment methods.
I already tried to signup for their partner. Without any luck.
We've done this before for a couple stores to allow clients to process payments through their own processor. The way we achieved this, is essentially through the following high-level steps:
Allow payments by Check (or similar offline method). We are going to replace this with the custom processor.
You'll notice that if you attempt to checkout via Check, that BigCommerce automatically creates the order for you, but sets the order status to Awaiting Payment. Upon submission the user is automatically sent to a 'Thank You' Order Confirmation page that contains both the Order ID and some payment instructions (such as where to send the check to).
Here's the trick -- Modify this 'Order Thank You' page to prompt the user for her or his credit card information. A simple HTML form will suffice here, performing the actual request via JavaScript.
Once you have the user's credit card data, you can then POST it to your own external server, where you would connect to and send data to whichever processor you are using. Additionally, you should make sure to send the Order ID to this program, so that you can connect to the BigCommerce API to load billing information, and then subsequently adjust the order status to either approved or declined depending on the response from your processor. Finally, you should send back some sort of response to the client to inform of the result of the charge attempt.
That's pretty much it in a nutshell. The way you integrate with the payment processor (step 4) is unique to whichever processor you are using. I hope this makes sense.
Although opinion based, I'm a huge fan of serverless technologies, and would suggest looking into AWS Lambda + AWS API Gateway. The benefit here is that you don't need to worry about creating an infrastructure or the associated concerns of security and scale. Rather, AWS Lambda allows you to simply upload your software, and allows it to be executed via an HTTP request to some defined endpoint set through the API Gateway. Lambda will scale automatically for you, and you don't need to worry about system level security concerns - only security at the application level. It's truly a set and forget setup, and a bleeding edge technology. Not to mention dirt cheap!
Implementing a new payment method is unsupported and requires hacky workarounds since we implement payment gateways via the core app. You can do this on blueprint by using an offline payment method and then using the API to update payment statuses, etc. I'd recommend using ActiveMerchant if you do wish to go down this path.

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