Re: Negate Content - Snort Rules

Also, the answer is “because you can’t do a relative match to something that doesn’t exist (distance:1; within:10;)”.

So, in order to do what you want to do, you have to do the positive match and then read backwards.  Which is why I ask what the error you’re receiving is

— 
Sent from my  iPad

> On Jun 12, 2021, at 13:48, [email protected] wrote:
> 
> What is the error you’re receiving?
> 
> — 
> Sent from my  iPad
> 
>>> On Jun 11, 2021, at 10:57, João Pedro Lola via Snort-sigs <[email protected]> wrote:
>>> 
>> Hello All,
>> 
>> In a snort rule, why can´t i have two negate contents and third not negate content? If i can, how do I write it to work?
>> 
>> Example:
>> 
>> alert tcp $HOME_NET $HTTP_PORTS -> $EXTERNA_NET $HTTP_PORTS (
>> msg:"a message...";
>>  flow:stateless; 
>> content:!"|76 69 64 65 6f 2f 6d 70 65 67|"; offset:13; depth:10;
>> content:!"|61 75 64 69 6f 2f 6d 70 65 67|"; distance:1; within:10; 
>> content:"|61 75 64 69 6f 2f 6d 70 65 67|"; distance:1; within:10; 
>> classtype:tcp-connection; sid:3024678; rev:1;)
>> 
>> Best Regards,
>> João Lola
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