Logwatch apache question?

[Knute Johnson]

I have a lot more of the following in my daily log.  Any idea what 
exactly the known hack attempt was?

 > Attempts to use known hacks by 197 hosts were logged 562 time(s) from:
 >     71.198.234.91: 14 Time(s)
 >
 >     66.169.235.10: 10 Time(s)
 >
 > A total of 197 sites probed the server
 >     108.201.92.73
 >     108.23.234.43

Could this be what's causing it?

knute at knutejohnson:/var/log/apache2$ cat access.log | grep 71.198.234.91
lonejuniper.com:80 71.198.234.91 - - [20/Nov/2011:10:57:03 -0800] "GET 
/tejon320.jpg HTTP/1.1" 200 8651 
"http://www.medfordfuel.com/Interstate_5_California.htm" "Mozilla/5.0 
(compatible; MSIE 9.0; Windows NT 6.0; WOW64; Trident/5.0)"
lonejuniper.com:80 71.198.234.91 - - [20/Nov/2011:10:57:03 -0800] "GET 
/alpaca320.jpg HTTP/1.1" 200 8237 
"http://www.medfordfuel.com/Interstate_5_California.htm" "Mozilla/5.0 
(compatible; MSIE 9.0; Windows NT 6.0; WOW64; Trident/5.0)"
216.240.58.140:80 71.198.234.91 - - [20/Nov/2011:10:57:27 -0800] "-" 408 
0 "-" "-"

Specifically the one with the 408 message?

Requests with error response codes
     408 Request Timeout
        null: 562 Time(s)

Is requesting a null page a hack?

Thanks,

-- 

Knute Johnson