On Wed, Jan 25, 2012 at 2:11 PM, Damien Hull <[email protected]> wrote:
> I just turned of active response this morning... I may leave it off
> unless I can fix this problem...
>

Write a rule to ignore that specific instance.

Something like this (TOTALLY UNTESTED):
<rule id="ID_GOES_HERE" level="0">
  <if_sid>31101</if_sid>
  <match>GET 
/theme/image.php?theme=moodlebook&image=favicon&rev=282&component=theme</match>
  <description>Ignore our janky theme 404s!</description>
</rule>

Personally I think you'd be better off with something else looking at
your web logs (heresy, I know). Web crap is waaaaaaaay too complicated
for a general purpose utility (primarily) worked on by volunteers to
grok properly. Use something like mod_security, and have OSSEC watch
its logs.

> On Wed, Jan 25, 2012 at 8:03 AM, sempai <[email protected]> wrote:
>> I alert and block on many but not all web servers for precisely this reason,
>> but I knew what Active Response did before I turned it on and complained
>> about it working.
>>
>> There are a lot of vulnerability probes and assessment tools that look
>> specifically for certain urls and generate 404s while doing so.  It's a
>> high-value signature, but requires more than rudimentary understanding of
>> web servers.
>>
>> On Wed, 25 Jan 2012 08:33:15 -0600, Steven Stern wrote:
>>
>> I get a lot of 404 alerts, and I let OSSEC block access when it's
>> multiples from the same IP. Typically, they're looking for phpmyadmin or
>> other common (and probably poorly secured tools) in a number of locations.
>>
>> On 01/24/2012 11:33 PM, Damien Hull wrote:
>>
>> It looks like someone was requesting thee favicon and the server replied
>> with "404"... How does that equal a level 10 alert? Anyway, here's the log
>> info. GET
>> /theme/image.php?theme=moodlebook&image=favicon&rev=282&component=theme
>> HTTP/1.1" 404 290 "-" "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1;
>> Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR
>> 3.0.30729; Media Center PC 6.0; .NET4.0C; InfoPath.3; IPH 1.1.21.4019)" On
>> Tue, Jan 24, 2012 at 10:32 AM, Jason 'XenoPhage' Frisvold
>> <[email protected]> wrote:
>>
>> On Jan 24, 2012, at 8:37 AM, Joe Gedeon wrote:
>>
>> You should look at your logs and see what is triggering the 400's and fix
>> that issue if it is a server side issue.
>>
>> Agreed. Basically, the web browser is trying to obtain something from the
>> server that's just not there. Thus, 400 errors are triggered. As a result,
>> OSSEC sees a bunch of these fly by and considers it an attack. It's far
>> better to fix the underlying problem than to alter OSSEC to ignore such
>> things.

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