Add SPF control

Signed-off-by: Bryan Frimin <bryan@frimin.fr>

controls/communication-security/email-security/COM-EMAIL-001_sender_policy_framework.md

@@ -0,0 +1,51 @@
+---
+id: "COM-EMAIL-001"
+category: "communication-security/email-security"
+revision-version: 1
+revision-date: "2024-01-07"
+estimate-time: "30m"
+frameworks:
+    - name: "soc2"
+      sections: ["CC6.1", "CC6.8"]
+---
+
+## Purpose
+SPF (Sender Policy Framework) prevents email spoofing by defining
+which mail servers are authorized to send emails on behalf of your
+domain. It helps receiving mail servers verify that incoming email
+from a domain comes from a host authorized by that domain's
+administrators.
+
+## Risk Assessment
+
+| Risk                            | Impact | Reason                                                               |
+|---------------------------------|--------|----------------------------------------------------------------------|
+| Phishing and Social Engineering | 8      | Reduces phishing by preventing email spoofing of company             |
+| Business Email Compromise (BEC) | 8      | Prevents attackers from impersonating trusted partners or executives |
+
+## Implementation
+
+1. Identify all legitimate email sources:
+   - Your mail servers
+   - Third-party services (e.g., Google Workspace)
+   - Marketing platforms
+   - Any other authorized email senders
+2. Create SPF record
+   ```
+   v=spf1 include:_spf.google.com ~all
+   ```
+   Where:
+   - `v=spf1`: Version of SPF
+   - `include:_spf.google.com`: Include Google's mail servers
+   - `~all`: Soft fail for others (can be changed to -all for hard fail)
+3. Add record to DNS:
+   - Create TXT record at domain root
+   - Publish SPF record in DNS
+   - Wait for DNS propagation
+   
+## Evidence
+
+- Screenshot of published SPF DNS record
+- Email header samples showing SPF pass
+- Documentation of authorized senders
+

controls/communication-security/email-security/COM-EMAIL-002_dkim_implementation.md

@@ -1,5 +1,5 @@
 ---
-id: "COM-EMAIL-001"
+id: "COM-EMAIL-002"
 category: "communication-security/email-security"
 revision-version: 1
 revision-date: "2024-01-07"