Suspicious Inbox Rule Creation With Forwarding or Deletion via M365 Exchange

ATT&CK techniques

Collection

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
- T1114.003Email Forwarding Rule
C2
Exfiltration
Impact

What it detects

This rule detects the creation or modification of a mailbox inbox rule that forwards, redirects, or deletes messages within Microsoft 365 Exchange, matching the mail-exfiltration tradecraft of the ARToken EvilTokens affiliate panel reported by Cisco Talos. After token theft the operators plant inbox rules to silently siphon or hide victim mail. This behavior signals attacker persistence and collection inside a compromised tenant.

Reporting behind it

Related detections9 linkedT1114.003 — drag to rearrange

Malicious Exchange Inbox Rule Hiding Workday Payroll Notifications via Payroll Pirate Compromise (via m365)

Malicious Mailbox Forwarding Rule Creation (via exchange)

Malicious Office 365 Email Forwarding Rule to External Domain (via office365)

Google Workspace login activity: Out-of-domain email forwarding

Detect Email Forwarding/Redirecting via Exchange PowerShell InboxRule Cmdlets on Windows

Windows PowerShell: New-InboxRule/Set-InboxRule Script Block Activity

Microsoft 365 Audit Logs: Inbox Rule Creation or Update with Email Hiding Actions

O365 Mail Forwarding and Redirecting Rule Changes

Azure Risk Event: Suspicious Inbox Forwarding

Suspicious Inbox Rule Creation With Forwarding or Deletion via M365 Exchange

Pivot detection · T1114.003 · 9 related

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

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