Re: Bug report - no content match on http_inspect port

[Joel Esler <jesler () sourcefire com>]

You should only put ports in the http_inspect config that you are running http services on, on your network.

3128 is a common proxy port, so it's included by default.

Joel

On Mar 4, 2011, at 9:57 AM, elof () sentor se wrote:

> Snort doesn't trigger alerts on traffic if that port is included in the 
> http_inspect ports.
>
>
> Example:
>
> A basic rule:
>
> alert tcp any 3128 -> any any (msg:"foo"; flow:from_server,established; 
> content:"login|3A| root"; sid:1234; rev:1;)
>
> If the snort.conf contain this http_inspect configuration, sid:1234 will 
> never trigger even if a packet is seen containing "login: root" from port 
> 3128. Bug!
>
> preprocessor http_inspect_server: server default profile all ports { 80 
> 3128 8080 } oversize_dir_length 500 no_alerts
>
>
> If I remove port 3128 from the configuration and try again, I get an 
> alert.
>
> preprocessor http_inspect_server: server default profile all ports { 80 
> 8080 } oversize_dir_length 500 no_alerts
>
>
> I tested it using this simple setup:
> Server: echo "login: root" | nc -l 3128
> Client: nc serverip 3128
>
> When the client connect, I get a logged event using the second config.
> When the client connect, I don't get any event using the first config.
> This is reproduceable.
>
> Could it be that http_inspect tries to normalise the string "login: root" 
> and by doing so breaks it, so that there are no matches?
>
> /Elof
>
> ------------------------------------------------------------------------------
> What You Don't Know About Data Connectivity CAN Hurt You
> This paper provides an overview of data connectivity, details
> its effect on application quality, and explores various alternative
> solutions. http://p.sf.net/sfu/progress-d2d
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--
Joel Esler
jesler () sourcefire.com
http://blog.snort.org && http://blog.clamav.net


------------------------------------------------------------------------------
What You Don't Know About Data Connectivity CAN Hurt You
This paper provides an overview of data connectivity, details
its effect on application quality, and explores various alternative
solutions. http://p.sf.net/sfu/progress-d2d
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