We recently upgraded the environment from 6.5 to 7.2 and ever since there is an upgradation in the environment we see that the rule fields are not getting extracted properly for Cisco message id 106100 but it is getting extracted for cisco message id 106123. We have defined the props and transforms still not able to extract the rule field for message id 106100. The rule field should be extracted by default but I see that some of the fields are not getting extracted by default but we need to extract it manually.
The is an observed behavior in Splunk 7.x versions, the FIELDALIAS overwrites the null value from the source field to the destination field and is having the values in it, So the final result is null value in the Destination field and because of which the baheviour change the rule field is not getting extracted.
So you need to makes these changes in the props.conf
Comment below in the $plunkhome/etc/apps/Spunk_TA_cisco-asa/default/props.conf
FIELDALIAS-fwsm_acl_for_rule= acl as rule(in cisco:fwsm stanza)