Layer-7. Filtring.. regex..

Hello,
I need to filter the query, which goes to the Web server through mikrotik.

The query looks like this:
host_name/getList.php?category=-1OR%20%20BENCHMARK(10000000,BENCHMARK(10000000,md5(current_date)))

I created a regexp in Layer7:
^(GET .BENCHMARK. /| get .BENCHMARK. /| .BENCHMARK.)

Then added to the firewall rule:
chain=forward action=drop layer7-protocol=BENCHMARK in /ip firewall filter

but it’s does not work

any one can help me ?