Customer Guidance for Reported Zero-day Vulnerabilities in Microsoft Exchange Server

parlevjo, your syntax looks a little malformed.  Try:

Get-ChildItem -Recurse -Path <Path_IIS_Logs> -Filter "*.log" | Select-String -Pattern "(?=.*autodiscover)(?=.*powershell)"

If it seems the command is taking forever, I've found the following to be much more performant:

Get-ChildItem -Recurse -Path <Path_IIS_Logs> -Filter "*.log" | Select-String -Pattern "^(?=.*autodiscover)(?=.*powershell)(?:.*)$"

Which translates to: for each line in each log file, match if you find the word "autodiscover" and the word "powershell," in either order, with zero or more characters (.*) before, between, and after.

Without using ^ and $, Select-String will chew on way more string data than it needs to.