This was the most generic regex I could find with the amount of information you shared, while staying minimally efficient I'd say:
| makeresults count=1
| eval _raw="[1/13/19 10:18:20:577 GMT] 00000097 LogOut O INFO: Sun Jan 13 10:18:20 GMT 2019: THIS IS MY MESSAGE STRING."
| rex "\[\d*\/\d*\/\d* \d{2}:\d{2}:\d{2}:\d{3}[^\]]+\].*INFO:[^:]+:\d{2}:\d{2}[^:]+:(?<_raw>.*)"
@jainkul123 ,
Give this a try,
"your search"|rex field=_raw "\w{3}\s\w{3}\s+\d{1,2}\s+\d{1,2}:\d{1,2}:\d{1,2}\s\w{3}\s\d{4}:\s(?<Message>.+)"
This works, thank you
If it works you should accept it to close out the question
You can try using the below regular expression.
\[.*\].*?\w{3}\s+\w{3}\s+\d{1,2}\s+\d{2}\:\d{2}\:\d{2}\s\S+\s+\d{4}\:\s+(?.*)