| name | implementing-mimecast-targeted-attack-protection |
| description | Deploy Mimecast Targeted Threat Protection including URL Protect, Attachment Protect, Impersonation Protect, and Internal Email Protect to defend against advanced phishing and spearphishing attacks. |
| domain | cybersecurity |
| subdomain | phishing-defense |
| tags | ["mimecast","email-security","targeted-threat-protection","url-protect","impersonation","attachment-sandboxing","phishing"] |
| version | 1.0 |
| author | mahipal |
| license | Apache-2.0 |
| nist_csf | ["PR.AT-01","DE.CM-09","RS.CO-02","DE.AE-02"] |
Implementing Mimecast Targeted Attack Protection
Overview
Mimecast Targeted Threat Protection (TTP) is a suite of advanced email security services designed to protect against sophisticated phishing, spearphishing, and targeted attacks. TTP consists of four core modules: URL Protect (real-time URL rewriting and click-time analysis), Attachment Protect (sandbox detonation of suspicious attachments), Impersonation Protect (BEC and whaling detection), and Internal Email Protect (scanning internal/outbound email for threats). As of November 2025, Mimecast enabled URL Pre-Delivery Action with Hold setting for all customers by default.
When to Use
- When deploying or configuring implementing mimecast targeted attack protection capabilities in your environment
- When establishing security controls aligned to compliance requirements
- When building or improving security architecture for this domain
- When conducting security assessments that require this implementation
Common Misconfigurations & Verification
- URL Protect in rewrite-only mode: without Pre-Delivery Action set to "Hold", a URL weaponized between delivery and click can still reach the user - enable pre-delivery hold (default since Nov 2025) and verify it on existing policies.
- Impersonation at Hit 3 for everyone: the default 3-indicator threshold misses single-signal VIP attacks - create a separate Hit 1 VIP definition for CEO/CFO/finance and keep Hit 3 for the general population.
- Attachment Protect "Safe File" only: static safe-file conversion alone misses behavior-based payloads - use Dynamic Configuration (full sandbox) for unknown senders and allow timeout for complex files (up to ~7 min).
- Internal Email Protect not enabled: without journaling from M365/Workspace, lateral phishing from a compromised internal account is invisible - enable IEP URL and attachment scanning.
- Over-broad permitted senders / managed URLs: blanket bypasses defeat URL and impersonation scanning - scope exceptions to specific automated systems and mailing lists.
- Verification: pilot on 50-100 users first; send a test URL, an EICAR/test attachment, and a VIP-impersonation BEC; confirm the URL is rewritten and blocked at click, the attachment is sandboxed within SLA, the impersonation is quarantined, and pre-delivery hold catches a weaponized URL before inbox.
Prerequisites
- Mimecast Email Security license with TTP add-on
- Administrative access to Mimecast Administration Console
- Microsoft 365 or Google Workspace environment
- MX records configured to route through Mimecast
- Understanding of email authentication (SPF, DKIM, DMARC)
