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

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 creation or modification of Exchange Online inbox rules that filter messages from myworkday.com and delete or move them to obscure folders. This behavior is associated with payroll pirate campaigns against US universities where attackers hide Workday payroll and direct deposit change notifications from compromised victims. Concealing these alerts lets attackers reroute salary payments without the victim noticing, making early detection critical.

Reporting behind it

Related detections8 linkedT1114.003 — drag to rearrange

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

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

Pivot detection · T1114.003 · 8 related

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