Snort mailing list archives

Are these rules from community.rules redundant?


From: Tyler Smith <tyler.smith () adventiumlabs com>
Date: Mon, 22 Jun 2015 10:03:56 -0500

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; 
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; 
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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