Confessions Of A Dangerous Mind

Following some email requests ( too many for that specific question ) that ive got to help various FORTIGATE ( by fortinet ) owners - to set their firewall security policy to block MSN Advertisment within the client ( as a Proof Of Concept ONLY ) ... and following an old post ( that i have posted here on march 13th 2007 - Link ) i am posting the requested configuration for the machines.

I have devided to re-post this , with better technical explenation - and in english this time , as a gesture to the "Security Bloggers Network" ( which i only post english feeds to , and this is one worth mentioning ).

the main concept is to block 3 reg-ex uri links that the messenger client gets its advertisment ads from. ( as you may or may not know , this IM uses HTTP to get things done , well - lets break its path...

[ note : configuration is made for the FortiOS mr5 patch 2 and tested on FGT60 ]

As i previsously posted , this is a good way of handeling messenger usage within organizations that do not approve end-user advertisment on its computer environment.

There are two ways of doing it ... one through the url filter engine , and the other one is through the IPS ( which i find much more exotic way of getting things done through deep packet inspection ).

Method 1 - URL Filter :

1. goto the CLI on the machine and paste the following configuration -

• config webfilter urlfilter
      edit 1
              config entries
                  edit "ad.msn.co.il/js.ng"
                      set action block
                  next
                  edit "rad.msn.com/ADSAdClient31.dll"
                      set action block
                      set type regex
                  next
                  edit "config.messenger.msn.com/Config/MsgrConfig.asmx"
                      set action block
                      set type regex
                  next
              end
          set name "block-msn-ad-engine"
      next
  end

2. choose the "block-msn-ad-engine" within your protection-profile of choice.

Method 2 - IPS :

1. go to the Intrusion Protection >> Signature >> Custom menu and add the following signatures -

• F-SBID( --name "bs_MSN-AD-Stop.A"; --protocol tcp; --flow established ; --regex "ADSAdClient31.dll"; --no_case)
• F-SBID( --name "bs_MSN-AD-Stop.B"; --protocol tcp; --flow established ; --content "ad.msn.co.il"; --no_case)
• F-SBID( --name "bs_MSN-AD-Stop.C"; --protocol tcp; --flow established ; --regex "MsgrConfig.asmx"; --no_case)

2. choose appropriate severity and include the severity in the desired protection-profile.

 

Disclaimer : this is a POC only , this kind of usage may conflict with the MSN Messenger usage aggreement , and i am not to take any responsibility for and unethical or illegal usage of this article and the information it provides. and although i tink using this information to violate any EULA or other agreement is wrong - if you use it - you are taking for responsability for it.

i am not sure that there is any violation , since all this solution does is changing the availability of web data to an application - so basically treating the application as a user in the network and denying it from getting to some internet content . legitimate isnt it ?