diff --git a/rules/windows/powershell/powershell_script/posh_ps_exchange_mailbox_smpt_forwarding_rule.yml b/deprecated/windows/posh_ps_exchange_mailbox_smpt_forwarding_rule.yml similarity index 95% rename from rules/windows/powershell/powershell_script/posh_ps_exchange_mailbox_smpt_forwarding_rule.yml rename to deprecated/windows/posh_ps_exchange_mailbox_smpt_forwarding_rule.yml index 67c4f2566..477446d26 100644 --- a/rules/windows/powershell/powershell_script/posh_ps_exchange_mailbox_smpt_forwarding_rule.yml +++ b/deprecated/windows/posh_ps_exchange_mailbox_smpt_forwarding_rule.yml @@ -1,11 +1,12 @@ title: Suspicious PowerShell Mailbox SMTP Forward Rule id: 15b7abbb-8b40-4d01-9ee2-b51994b1d474 -status: test +status: deprecated description: Detects usage of the powerShell Set-Mailbox Cmdlet to set-up an SMTP forwarding rule. references: - https://m365internals.com/2022/10/07/hunting-in-on-premises-exchange-server-logs/ author: Nasreddine Bencherchali (Nextron Systems) date: 2022-10-26 +modified: 2026-03-01 tags: - attack.exfiltration logsource: diff --git a/rules-threat-hunting/windows/powershell/powershell_script/posh_ps_email_forwarding_activity.yml b/rules-threat-hunting/windows/powershell/powershell_script/posh_ps_email_forwarding_activity.yml new file mode 100644 index 000000000..27c9d50e8 --- /dev/null +++ b/rules-threat-hunting/windows/powershell/powershell_script/posh_ps_email_forwarding_activity.yml @@ -0,0 +1,43 @@ +title: Mail Forwarding/Redirecting Activity Via ExchangePowerShell Cmdlet +id: 0c7686d5-c74e-4292-b224-2a08e956ebc4 +related: + - id: c726e007-2cd0-4a55-abfb-79730fbedee5 + type: similar + - id: 15b7abbb-8b40-4d01-9ee2-b51994b1d474 + type: obsolete +status: experimental +description: Detects email forwarding or redirecting activity via ExchangePowerShell Cmdlet +references: + - https://redcanary.com/blog/email-forwarding-rules/ + - https://github.com/PwC-IR/Business-Email-Compromise-Guide/blob/fe29ce06aef842efe4eb448c26bbe822bf5b895d/PwC-Business_Email_Compromise-Guide.pdf +author: Nasreddine Bencherchali (Nextron Systems), Marco Pedrinazzi (@pedrinazziM) (InTheCyber) +date: 2026-03-01 +tags: + - attack.collection + - attack.t1114.003 + - attack.defense-evasion + - attack.t1564.008 + - attack.exfiltration + - attack.t1020 + - detection.threat-hunting +logsource: + product: windows + category: ps_script + definition: 'Requirements: Script Block Logging must be enabled' +detection: + selection_cmdlet: + ScriptBlockText|contains: + - 'New-InboxRule' + - 'Set-InboxRule' + - 'Set-Mailbox' + selection_params: + ScriptBlockText|contains: + - 'ForwardAsAttachmentTo' + - 'ForwardingAddress' + - 'ForwardingSmtpAddress' + - 'ForwardTo' + - 'RedirectTo' # Also covers "RedirectToRecipients" + condition: all of selection_* +falsepositives: + - Legitimate mail forwarding rules created by users or administrators to forward email to designated internal or external recipients for business or operational purposes. +level: medium diff --git a/rules-threat-hunting/windows/powershell/powershell_script/posh_ps_inbox_rule_creation_or_update_activity.yml b/rules-threat-hunting/windows/powershell/powershell_script/posh_ps_inbox_rule_creation_or_update_activity.yml new file mode 100644 index 000000000..eea44f467 --- /dev/null +++ b/rules-threat-hunting/windows/powershell/powershell_script/posh_ps_inbox_rule_creation_or_update_activity.yml @@ -0,0 +1,42 @@ +title: Inbox Rules Creation Or Update Activity Via ExchangePowerShell Cmdlet +id: 04580eed-e1d6-426b-a570-f6e64a4577f7 +related: + - id: d3577be1-42c9-44a7-b56e-2e8de97349d3 + type: similar +status: experimental +description: | + Detects inbox rule creation or update via ExchangePowerShell cmdlet, a technique commonly observed in Business Email Compromise (BEC) attacks to hide emails. + The usage of inbox rules can be a sign of a compromised mailbox, where an attacker is attempting to evade detections by suppressing or redirecting incoming emails. + Analysts should review these rules in context, validate whether they reflect normal user behavior, and correlate with other indicators such as unusual login activity or recent mailbox rule modifications. +references: + - https://redcanary.com/threat-detection-report/techniques/email-hiding-rules/ + - https://learn.microsoft.com/it-it/powershell/module/exchangepowershell/new-inboxrule?view=exchange-ps + - https://learn.microsoft.com/it-it/powershell/module/exchangepowershell/set-inboxrule?view=exchange-ps +author: Marco Pedrinazzi (@pedrinazziM) (InTheCyber) +date: 2026-02-10 +tags: + - attack.defense-evasion + - attack.t1564.008 + - attack.exfiltration + - attack.collection + - attack.t1114.003 + - detection.threat-hunting +logsource: + product: windows + category: ps_script + definition: 'Requirements: Script Block Logging must be enabled' +detection: + selection_cmdlet: + ScriptBlockText|contains: + - 'New-InboxRule' + - 'Set-InboxRule' + selection_params: + ScriptBlockText|contains: + - 'DeleteMessage' + - 'MarkAsRead' + - 'MoveToFolder' + - 'SubjectOrBodyContainsWords' + condition: all of selection_* +falsepositives: + - Legitimate inbox rules created by users or administrators to manage email flow such as filtering, organizing, or automating email handling. +level: medium