Detect Email Spoofing in Sumo Logic CSE
This detection identifies email spoofing attempts where adversaries manipulate email headers — particularly the FROM, Reply-To, and Display Name fields — to impersonate legitimate senders. The detection focuses on emails that fail SPF, DKIM, or DMARC authentication checks, mismatches between the envelope sender (Return-Path/MailFrom) and the header From address, and abuse of Microsoft 365 Direct Send to bypass authentication. Spoofed emails are frequently used to enable phishing, business email compromise (BEC), and impersonation attacks against high-value targets such as executives, finance teams, and third-party vendors.
MITRE ATT&CK
- Tactic
- Defense Evasion
- Technique
- T1672 Email Spoofing
- Canonical reference
- https://attack.mitre.org/techniques/T1672/
Sumo Detection Query
_sourceCategory=o365/management
| json auto
| where operation in ("Receive","MessageDelivered","New-InboxRule","Set-InboxRule","UpdateInboxRules")
| where spf_result matches /(fail|softfail)/i OR dkim_result = "fail" OR dmarc_result = "fail"
OR operation matches /InboxRule/i
| if(spf_result = "fail" AND dkim_result = "fail", 90,
if(dmarc_result = "fail", 80,
if(operation matches /InboxRule/i, 85, 65))) as risk_score
| if(operation matches /InboxRule/i, "MailboxRule",
if(dmarc_result = "fail", "DMARCFail", "AuthFailure")) as detection_type
| where risk_score >= 65
| count by sender_address, recipient_address, detection_type, risk_score
| sort - risk_scoreSumo Logic detection for Email Spoofing (T1672). Identifies adversary email spoofing behaviors using Sumo Logic's search pipeline with field extraction and anomaly classification.
Data Sources
Required Tables
False Positives & Tuning
- Legitimate bulk email services (Mailchimp, SendGrid, Constant Contact) that send on behalf of a domain without proper DKIM/SPF alignment — review if SenderMailFromDomain is a known ESP subdomain
- Internal applications or multifunction printers using Microsoft 365 Direct Send with a functional mailbox From address but no DKIM signing configured
- Third-party HR, legal, or CRM platforms authorized to send on behalf of the organization that have not completed DMARC alignment setup
Other platforms for T1672
Testing Methodology
Validate this detection against 3 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1Send Spoofed Email via Python SMTP to External Relay (No Auth)
Expected signal: Email delivery logs showing From header '[email protected]' with envelope sender '[email protected]' — triggering SenderFromDomain != SenderMailFromDomain mismatch. SPF will fail since [email protected] is not authorized to send for contoso.com.
- Test 2Validate DMARC Policy Weakness on Target Domain
Expected signal: DNS query logs (if captured via Sysmon Event 22 on Windows or auditd/bind logs on Linux) showing TXT record lookups for _dmarc and _domainkey subdomains. No email telemetry generated by this test step.
- Test 3Spoofed Email via SendGrid API with Mismatched From Header (Authorized Test)
Expected signal: Email delivery to test mailbox with From header showing [email protected] but Authentication-Results showing dkim=pass (SendGrid DKIM) and spf=pass (SendGrid IP) — but DMARC will fail due to domain alignment mismatch between contoso.com (From header domain) and sendgrid.net (DKIM/SPF domain). The SenderFromDomain vs SenderMailFromDomain mismatch will be logged in EmailEvents.
References (9)
- https://attack.mitre.org/techniques/T1672/
- https://www.proofpoint.com/us/blog/threat-insight/ta427-north-koreas-research-focused-social-engineering
- https://www.cloudflare.com/learning/email-security/dmarc-dkim-spf/
- https://dmarc.org/overview/
- https://www.proofpoint.com/us/blog/email-and-cloud-threats/dmarc-protection
- https://www.ic3.gov/PSA/2024/PSA240626
- https://www.microsoft.com/en-us/security/blog/2024/05/28/moonlighting-in-your-mailroom-how-north-korea-exploits-direct-send
- https://learn.microsoft.com/en-us/microsoft-365/security/office-365-security/anti-spoofing-spoof-intelligence
- https://learn.microsoft.com/en-us/exchange/mail-flow-best-practices/how-to-set-up-a-multifunction-device-or-application-to-send-email-using-microsoft-365
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