I have hosted my Prestashop at Fastdomain server it's like the 4th year, the website is stable and working fine till 3 days ago where my email inbox got full of spam and more than 300K requests on the site causing the site to go down.
I activated the basic protection from Sitelock provided from Fastdomain Cpanel, it worked fine for two days and the site is down again cuz of another strike.
Fastdomain support tried to fix it but no instant method they said the problem is caused due to script overuse in send to friend module, even though this module is an original PrestaShop module, and they said the website will "recover" in few hours.
any comment or thoughts? how t respond to such attack!? my website is elektrojo.com and am using the up to date version
This appears to be a common problem. Not only is it taking your site down, it may be being used to spam others, which has the risk of getting your domain blacklisted.
In that thread was linked an updated version of the module supporting a CAPTCHA, along with a similar modification for product reviews. It seems to be for PrestaShop 1.5 and 1.6.
If you have some kind of a "backend" which you can update modules on, you should also do that.
Another suggestion is to use fail2ban to detect repeated attempts to access this feature and block it. You may not have the necessary access to do that, but if not, your hosts should be able to.
Failing that, you should remove the sendtoafriend code (ensure the files are actually gone from their original location) until you have found a way to harden it, since it's being abused to take your site down.