How to block malformed requests to Apache

I'd like to block malformed requests like these:

79.26.188.208 - - [05/Apr/2011:13:47:38 +0200] "\xae\xe1\x0fi\xca\xeba\xdfm\x9d\xb5\xc0yr-n\x05Z\x9f\xa7\x05\xa1g" 200 4855 "-" "-"
82.51.130.83 - - [05/Apr/2011:18:25:38 +0200] "T\xd0\xc55\xc3A\xcd\xd0" 200 4855 "-" "-"

What is the preferred method?

Solution 1:

mod_security is useful for blocking many of these requests.

It detects known exploit patterns and blocks them.

Solution 2:

Following Mikel's lead I added this mod_security rule

SecRule REQUEST_METHOD "!^(?:GET|HEAD|OPTIONS|POST|CONNECT)$"

and now only legitimate requests pass through.