A denial of service exists in counter.exe version 2.70, a fairly popular webhit counter used on the Win32 platform with web servers such as IIS and

WebSite Pro.

1) When someone requests :

http://no-such-server-really/scripts/counter.exe?%0A this will create an

entry in counter.log of a blank line then a ",1" . If the person then

refreshes their browser and requests it again you get an Access Violation in

counter.exe - the instruction at 0x00414c0a referenced memory at 0x00000000.

2) When someone requests:

http://no-such-server-really/scripts/counter.exe?AAAAAover-2200-As you get a

similar problem - though not a buffer overrun.

Whilst in a state of "hanging" all other vaild requests for counter are

queued and not dealt with until someone goes to the console and okays the AV

messages. Added to this memory can be consumed if the page is continuosly


Thanks to David Litchfield for the heads up