Detecting Email Forwarding Rules Attack Skill

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

Formulate Hypothesis: Define a testable hypothesis based on threat intelligence or ATT&CK gap analysis.
Identify Data Sources: Determine which logs and telemetry are needed to validate or refute the hypothesis.
Execute Queries: Run detection queries against SIEM and EDR platforms to collect relevant events.
Analyze Results: Examine query results for anomalies, correlating across multiple data sources.
Validate Findings: Distinguish true positives from false positives through contextual analysis.
Correlate Activity: Link findings to broader attack chains and threat actor TTPs.
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 | | Sysmon | Detailed Windows event monitoring | | Velociraptor | Endpoint artifact collection and hunting | | Sigma Rules | Cross-platform detection rule format |

Common Scenarios

Scenario 1: BEC actor creating forwarding rule to external email
Scenario 2: Compromised account with rule deleting security alerts
Scenario 3: Inbox rule forwarding CEO emails to attacker mailbox
Scenario 4: OAuth app abuse creating transport rules for data collection

Output Format

Hunt ID: TH-DETECT-[DATE]-[SEQ]
Technique: T1114.003
Host: [Hostname]
User: [Account context]
Evidence: [Log entries, process trees, network data]
Risk Level: [Critical/High/Medium/Low]
Confidence: [High/Medium/Low]
Recommended Action: [Containment, investigation, monitoring]

Agent Skills: Detecting Email Forwarding Rules Attack

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