🍪 How cookies can manipulate new customers
Tags: computerscience, cookies, webdev
Published: 2021-08-08 19:31:00

[**Original post**](https://krypton.ninja/How-cookies-can-manipulate-new-customers)

Who has not been attracted by prices of a product on a website? How cheap this product is compared to another website, or the opposite; how expensive the price is compared to other websites.

I have been a *victim* of price manipulation a few months ago and decided to share it so that other people don't get manipulated like me; however at the end I won 😎

## 📜 The Story
*Before anything starts, I wanted to let you know I've hidden as much information as possible to not identify the seller.*

So I've ordered contact lenses for myself quite some time ago. I remember the price was around 70 CHF (~ 76 USD) and I've found this price thanks to [Toppreise](https://toppreise.ch), which is a website to compare prices of a product based on many different swiss shops and sellers.
I wanted to order the same pack of 90 lenses a few months ago and have seen that the price had changed; it was around 90 CHF (~ 98 USD), I still added the product in my cart.
After looking on Toppreise again, the price was still marked as the price I've paid the last time I've ordered my lenses. After clicking on the link provided by Toppreise to purchase these lenses I see the ~ 70 CHF price again! After reloading my page on the previous cart it also was ~ 70 CHF!
What could've gone wrong in my previous steps to purchase my lenses 🤔

## 🤠 My Investigation
The fact that the price of the lenses changed upon reload of the cart really brought me into thinking of how they could've done this.

### 🎬 The Start
So I started by opening a **private** tab in my browser to look at the price of the lenses again. The price still was the 90-ish CHF of my previous attempt:
![Price Before](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/z3z70vkjhnvlnwmm60on.png)
So I went to the website to compare the prices and there was only one offer for the pack anyways, which was around 70 CHF
![Product Compared](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/o45ke1kl69nekymfx2uq.jpg)
I decided to click on the link to get to the offer, and the price had changed to the 70-ish CHF again!
![Price After](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/fy3njdh6gzljs3fgy7cs.png)

### 🕵️‍♂️ The Investigation
Now I definitely knew there was something with that link going on, it's almost impossible to click on a link and get a completely different price for the exact same product...
So I took the link and always closed my browser, opened a new private tab and pasted the link in it always with one GET parameter removed. I did this until the price didn't changed anymore, which would mean this is the important parameter. The link was quite big and looking to something like that:
> https://www.website.ch/product/cl/1337?VariationSKU=37&ish_cs=282075&awc=464935_228990_345003&utm_source=Affiliate_Window&utm_medium=Affiliate&utm_campaign=512227&wt_mc=am129545&utm_id=635365_987691_482693

The important parameter ended up being the parameter `ish_cs`. Upon further research I realized this parameter would give me no additional information.
I decided to take a look at the cookies of the website 🍪

### 💡 The Discovery & Ending
It didn't really took me long to see that new cookies have been added after using that parameter on the URL.
These were the cookies before:
![Cookies Before](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/2l9xm6k93zho9hk2yn5w.jpg)
And these the cookies after:
![Cookies After](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/h11wowijhpjm9p4ij73y.jpg)
As you can see by my awesome hand drawing there's a new temporary cookie named `cs_`, quite close to our previous parameter `ish_cs` 😏

After removing this cookie from my saved cookies it showed the expensive price again :D

## 🥳 The Victory
After knowing the price of the product would be lower when you have this cookie I've decided to order it; it ended up coming to me with written on the receipt: 73 CHF.

What I've learned from this small investigation is that you should always to try to compare the product you want to purchase with other shops and sellers, at least in Switzerland. At the end you end up paying less for exactly the same.

Now if this is an attempt from the shop to gain new customers will always be unknown to me... But one thing is for sure, they don't give to everyone the same price on their products 😊


*PS: This is my first post, so I don't really know how to make it entertaining and looking style wise good, any suggestions will be appreciated.*