detecting-email-forwarding-rules-attack

name	detecting-email-forwarding-rules-attack
description	Detect malicious inbox/mail-flow forwarding rules that adversaries create to maintain persistent access to email communications for intelligence collection and business email compromise. Use when hunting for suspicious auto-forwarding, hidden mailbox rules, or T1114-style email collection persistence after a compromised account or BEC incident.
domain	cybersecurity
subdomain	threat-hunting
tags	["threat-hunting","mitre-attack","email-forwarding","persistence","bec","t1114","proactive-detection"]
version	1.0
author	mahipal
license	Apache-2.0
d3fend_techniques	["Restore Object","Restore Configuration","Application Configuration Hardening","Application Hardening","Disable Remote Access"]
nist_csf	["DE.CM-01","DE.AE-02","DE.AE-07","ID.RA-05"]
mitre_attack	["T1046","T1057","T1082","T1083","T1547"]

Detecting Email Forwarding Rules Attack

When to Use

• When proactively hunting for indicators of detecting email forwarding rules attack in the environment
• After threat intelligence indicates active campaigns using these techniques
• During incident response to scope compromise related to these techniques
• When EDR or SIEM alerts trigger on related indicators
• During periodic security assessments and purple team exercises

Prerequisites

• EDR platform with process and network telemetry (CrowdStrike, MDE, SentinelOne)
• SIEM with relevant log data ingested (Splunk, Elastic, Sentinel)
• Sysmon deployed with comprehensive configuration
• Windows Security Event Log forwarding enabled
• Threat intelligence feeds for IOC correlation

Workflow

1. Formulate Hypothesis: Define a testable hypothesis based on threat intelligence or ATT&CK gap analysis.
2. Identify Data Sources: Determine which logs and telemetry are needed to validate or refute the hypothesis.
3. Execute Queries: Run detection queries against SIEM and EDR platforms to collect relevant events.
4. Analyze Results: Examine query results for anomalies, correlating across multiple data sources.
5. Validate Findings: Distinguish true positives from false positives through contextual analysis.
6. Correlate Activity: Link findings to broader attack chains and threat actor TTPs.
7. Document and Report: Record findings, update detection rules, and recommend response actions.

Key Concepts

Concept	Description
T1114.003	Email Forwarding Rule
T1114.002	Remote Email Collection
T1098.002	Additional Email Delegate Permissions

Tools & Systems

Tool	Purpose
CrowdStrike Falcon	EDR telemetry and threat detection
Microsoft Defender for Endpoint	Advanced hunting with KQL
Splunk Enterprise	SIEM log analysis with SPL queries
Elastic Security	Detection rules and investigation timeline