274. That's How Phantom Taurus Abuses Exchange Management Shell

Hello everyone!

I hope you've already checked Unit42's report on Phantom Taurus. And today we'll look at how this cluster abused Exchange Management Shell for email collection.

According to the first report on Phantom Taurus, the adversary leveraged Exchange Management Shell (exshell.psc1) to collect selected emails and save them to CSV:

powershell.exe -psconsolefile "C:\Program files\microsoft\exchange server\v15\bin\exshell.psc1" -command "get-mailbox -Filter \"UserPrincipalName -Like \"*foreign*\"\" -ResultSize Unlimited | get-mailboxstatistics | sort-object TotalItemSize -Descending | Select-Object DisplayName,Alias,TotalItemSize -First 30 | export-csv c:\users\public\<redacted>\<redacted>.csv"

powershell.exe -psconsolefile "C:\Program files\microsoft\exchange server\v15\bin\exshell.psc1" -command "Get-MessageTrackingLog -ResultSize Unlimited | Where-Object {$_.Recipients -like \"*@<redacted>.gov.<redacted>\"}| select-object Sender,{$_.Recipients},{$_.MessageSubject} | export-csv c:\users\public\<redacted>\<redacted>.csv"

Why not to look for related PowerShell cmdlets?

event_type: "processcreatewin"

AND

proc_file_path: "powershell.exe"

AND

cmdline: ("get-mailbox" OR "get-mailboxstatistics")

See you tomorrow!

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