[Snort-sigs] Flowbit Warnings

wkitty42 at windstream.net wkitty42 at windstream.net
Fri Jun 15 11:35:15 EDT 2018


On 06/13/2018 12:44 PM, Gerry Carpinetti via Snort-sigs wrote:
> I did some reading on flowbit warnings and how to fix them but after the changes 
> I still receive the warnings. I used Notepad++ to open a rules file, than used 
> Search -> Find In Files "selected the C:\Snort\rules folder than entered 
> "flowbits:set" into the Find What box, I replaced all flowbits:set to 
> flowbits:isset..


wasn't this already discussed in snort-users? you were answered over there... 
one of those answers was mine...


from that topic:
1. when you edited those rules, you broke them...
2. there are two rules that you can enable that will stop those warnings...
3. here is my response to you in snort-users where the original discussion took 
place...

----->8 snip 8<-----
On 06/13/2018 09:29 PM, Gerry Carpinetti via Snort-users wrote:
> I have noticed some have flowbits in 2 different sections of a single line 
> of> code for example: Flowbits:isset, file.swf; and again flowbits:set,
> file.swf.cff which is the Warning is set but not ever checked.

look at that very closely... it is checking if the file.swf flowbit is set... if 
it is and the rest of the rule matches, then the file.swf.cff flowbit is also 
set... now you have two flowbits set... the first indicates there is a swf file 
and the second indicates the swf file is utilizing the "CFF Feature count"...


> So how are you going to handle one of these that has flowbits mentioned 
> twice in a single line and some have matching SID’s. So the question is which
> one are you suppose to modify when a line has 2 sections for flowbits???

you don't modify any of them! you find at least one rule that has 
"isset,file.swf.cff" and enable it by removing the "#" from the beginning of its 
line...

in the rules sets that i have, that means enabling 25681 and/or 25683...
----->8 snip 8<-----




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