Strange website behaviour - GET parameter with a specific value is causing the website to redirect to 403

Question

I have a website running Joomla! (it's not mine, so I don't know how exactly it is constructed).

I've encountered a very strange problem: when I'm using the phpMyAdmin and I want to edit an entry in a table - I get an error 403. If I copy the link location of the button Edit and place it in a new tab - I get the same. By trial and error I found out, that if I replace the where_clause GET parameter's value's part %60id%60 with anything else (%60foo%60 or id, for example) - everything works as expected.

Do you have any ideas, what could cause such weird behavior? Why id? Why is it so special?

P.S. %60 stands for `

Answer 1

Almost every time I've found this strange behaviour there was some sort of security mod in the server, either at web server level or at PHP level. Hosting providers are often not even aware of it, perhaps because it's a default component of their control panel.

Your only chance is probably to find out what exact module there is and read the documentation to determine whether you can change the settings.