Re: Are these rules from community.rules redundant?

[Nick Randolph <drandolph () sourcefire com>]

Yes, in addition to sid:27628.

On 06/22/2015 11:03 AM, Tyler Smith wrote:
> I was doing an evaluation of the community.rules made available on the 
> Snort web page <https://www.snort.org/downloads/#rule-downloads>, and 
> noticed these two rules:
>
> |Rule @ line 2643: alert udp $HOME_NET any -> any 53 (msg:"BLACKLIST DNS request for known malware domain documents.myPicture.info"; 
> flow:to_server; byte_test:1,!&,0xF8,2; content:"|09|documents|09|myPicture|04|info|00|"; fast_pattern:only; metadata:impact_flag red, 
> policy balanced-ips drop, policy security-ips drop, ruleset community, service dns; 
> reference:url,fireeye.com/blog/technical/2013/08/survival-of-the-fittest-new-york-times-attackers-evolve-quickly.html  
> <http://fireeye.com/blog/technical/2013/08/survival-of-the-fittest-new-york-times-attackers-evolve-quickly.html>; classtype:trojan-activity; 
> sid:27625; rev:2;)
>
> Rule @ line 2644: alert udp $HOME_NET any -> any 53 (msg:"BLACKLIST DNS request for known malware domain ftp.documents.myPicture.info"; 
> flow:to_server; byte_test:1,!&,0xF8,2; content:"|03|ftp|09|documents|09|myPicture|04|info|00|"; fast_pattern:only; metadata:impact_flag 
> red, policy balanced-ips drop, policy security-ips drop, ruleset community, service dns; 
> reference:url,fireeye.com/blog/technical/2013/08/survival-of-the-fittest-new-york-times-attackers-evolve-quickly.html  
> <http://fireeye.com/blog/technical/2013/08/survival-of-the-fittest-new-york-times-attackers-evolve-quickly.html>; classtype:trojan-activity; 
> sid:27626; rev:2;)
> |
>
> Doesn't the |content| option in the first rule 
> (||09|documents|09|myPicture|04|info|00||) make the 2nd rule 
> redundant? That is, the 1st rule will always trigger if the 2nd rule 
> does because its |content| option is a substring of the 2nd's 
> |content| option (||03|ftp|09|documents|09|myPicture|04|info|00||)
>
> Thanks,
> Tyler
>
>
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