Suspicious Mailbox Forwarding Rule Creation Following AiTM Phishing

ATT&CK techniques

Initial Access → Collection

Recon
Resource Dev
Initial Access
- T1078Valid Accounts
Execution
Persistence
- T1078Valid Accounts
Priv Esc
- T1078Valid Accounts
Defense Evasion
- T1078Valid Accounts
Cred Access
Discovery
Lateral Movement
Collection
- T1114.003Email Forwarding Rule
C2
Exfiltration
Impact

What it detects

This rule detects the creation or modification of mailbox inbox rules that forward, redirect, or delete incoming messages, a common post-compromise action performed by operators of the Sneaky2FA adversary-in-the-middle phishing kit. After stealing session tokens attackers add hidden forwarding rules to maintain access to victim correspondence, so this activity is a key sign of business email compromise.

Reporting behind it

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Suspicious Mailbox Forwarding Rule Creation Following AiTM Phishing

Pivot detection · T1078 · 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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