#Write-Host "Checking rules for $($mailbox.displayname) - $($mailbox.primarysmtpaddress)" -foregroundColor Green $mailboxes = Get-Mailbox -ResultSize Unlimited | Select-Object -Property SamAccountName, UserPrincipalName, PrimarySmtpAddress
$LogTime = Get-Date -Format "MM-dd-yyyy_hh-mm-ss" This PowerShell script is also available on our GitHub here.Īdd-PSSnapin .SnapIn So, how can we detect the hidden rules during the incident response? We have modified a PowerShell script based on GCITS, which also includes “-IncludeHidden” parameters, “RedirectTo” conditions. Now, attackers are watching your mailbox and hiding their existence. You may need to refresh the interface several times to see the new results. When back to the OWA interface and Outlook interface, the evil forwarding rules are now hidden but still work. The PR_RULE_MSG_NAME_W value in the bottom window will suggest us the name of the “Evil forwarding rule”.Ĭlear the value “PR_RULE_MSG_NAME_W” and “PR_RULE_MSG_PROVIDER_W” value, and “Save Changes”.
The top window does not clearly indicate which rule is the “Evil rule” we are looking for. Right-click Inbox and then select “Open associated contents table”. Choose the correct “Outlook” profile in MFCMAPIĪfter logon, right-click and then “Open store”.Įxpand Mailbox, IPM_SUBTREE, and finally Inbox. To use MFCMAPI Editor, it is better to use it on a computer already with Microsoft Outlook and a user profile already configured. It is available here. In this experiment, we use the version MFCMAPI.圆4.exe.0.01. After compromising a user account, the attacker adds an evil forwarding rule.
#SPLUNK INPUTS.CONF MONITOR CSV WINDOWS#
Lab Environment: Windows 2016 and Exchange 2016 with the latest patches installed. In this section, we are going to simulate the action performed by an attacker. That’s why we will discuss it for On-Premise Exchange such as Exchange 2013, 2016 & 2019. There are different research articles discussing the hidden inbox forward rule on O365 including Compass Security, Matthew Green, and GCITS. In order to make the victim(s) even harder to detect the forward rules, attackers use some more advanced techniques to hide the forward rules. In many exchange email account compromise case investigations, attacker tends to add an inbox rule and forward victims’ email to an email account under the attacker’s control. Today, we are going to discuss detect hidden inbox forward rule in On-Premise Exchange. You can use the monitor input to add nearly all your data sources from files and directories. You can also use a universal or heavy forwarder, as you would with Splunk Cloud Platform.
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