Strange URL containing 'A=0 or '0=A in web server logs

Question

During the last weekend some of my sites logged errors implying wrong usage of our URLs:

...news.php?lang=EN&id=23\'A=0

or

Answer 1

since this is a very old version of FireFox, I blocked it in my htaccess file -

RewriteCond %{HTTP_USER_AGENT} Firefox/3\.5\.2 [NC]
RewriteRule .* err404.php  [R,L]