How to detect a newly sessionid with SPL and alert.

[umou7]

I want to do a security log monitoring and using splunk alert feature to send email notifications.

The security log and trigger condition is like this:

_time, SessionID,  filedA, fieldB

yyyymmdd,11111, xxxx,yyyyy

yyyymmdd,11111,bbbb,ccccc

yyyymmdd,22222,bbbb,ccccc

........

as this is a syslog monitoring task ,  I want to trigger an alert whenever a newly SessionID is detected.

It means the same SessionIDwill not be notified twice.

My SPL will be like below:

....| stats count by SessionID

Regarding to the alert configuration, which condition should I use?
Or is it possible to do this mostly in the base SPL?

Regards,

[Nisha18789]

hi @umou7 , below can be the approach for this:

1) create an inputlookup with all the sessionid's which are present in the log till now.

2) in the alert logic, join with this lookup you created in step1 and filter out the session id which does not match with the session id in lookup. Append this new session_id in the lookup created in step 1 and use alert action to send email if more than zero records found.

If you need help with the query, please let me know.

Please upvote my response if this answers your question.

[umou7]

Thank you very much @Nisha18789  .

I am also considering of using a lookup table.

But I am worry about that the lookuptable will become larger and larger so that it will give an impact on performance.

Could you give me some advice on this?

It would be appreciated if you could give me an example of the query with bellow approaches you mentioned.

Did you mean that put step 1)  in a scheduled search, and put step 2) only in the alert logic ?

[Nisha18789 · Accepted solution]

hi @umou7 , another option would be to write the session ids to summary index (you get this option when you create a report). However lookups are faster and you can use a KV store lookup which is faster than a lookup file. 

logic for alert with lookup will be like :

...| table _time, sessionid, otherfield1

| join type=outer sessionid

     [ search |inputlookup sessionhistory.csv

        |table sessionid | eval found_in_history=1]

| where isnull(found_in_history)

|outputlookup sessionhistory.csv append=true

now set alert action as email when result count > 0

Remember, first time when you are create the lookup you have to run a query for all time to populate the sessionid in the lookup, after that above alert logic will keep appending. 

[umou7]

Thank so much @Nisha18789 ,

This is what I wanted and it works well as expected.

I will populated the sessionids to a KV store lookup as you suggested.

Regards,

Mou