What it does. Deploys and configures Mimecast Targeted Threat Protection (TTP) modules -- URL Protect (click-time URL rewriting/analysis), Attachment Protect (sandbox detonation), Impersonation Protect (BEC/whaling detection), and Internal Email Protect -- for Microsoft 365 or Google Workspace. Use when defending against phishing, spearphishing, or business email compromise, or configuring TTP policies in the Mimecast Administration Console. Part of mukul975/Anthropic-Cybersecurity-Skills (817 security skills) (mukul975/Anthropic-Cybersecurity-Skills).

Install

• npx skills add mukul975/Anthropic-Cybersecurity-Skills --skill implementing-mimecast-targeted-attack-protection, or copy the skill folder into ~/.claude/skills/implementing-mimecast-targeted-attack-protection/.
• Raw file: curl -sL https://raw.githubusercontent.com/mukul975/Anthropic-Cybersecurity-Skills/HEAD/skills/implementing-mimecast-targeted-attack-protection/SKILL.md

SKILL.md (verbatim)

name: implementing-mimecast-targeted-attack-protection
description: >-
  Deploys and configures Mimecast Targeted Threat Protection (TTP) modules --
  URL Protect (click-time URL rewriting/analysis), Attachment Protect (sandbox
  detonation), Impersonation Protect (BEC/whaling detection), and Internal Email
  Protect -- for Microsoft 365 or Google Workspace. Use when defending against
  phishing, spearphishing, or business email compromise, or configuring TTP
  policies in the Mimecast Administration Console.
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
mitre_attack:
- T1566
- T1598
- T1534
- T1036
mitre_f3:
  version: '1.1'
  tactics:
  - initial-access
  - reconnaissance
  - stealth
  - resource-development
  techniques:
  - id: T1660
    name: Phishing
    tactic: initial-access
    source: attack
  - id: T1598
    name: Phishing for Information
    tactic: reconnaissance
    source: attack
  - id: T1672
    name: Email Spoofing
    tactic: stealth
    source: attack
  - id: F1032
    name: Impersonate Official
    tactic: initial-access
    source: f3
  - id: F1020.002
    name: 'Create Fake Materials: Fake Website'
    tactic: resource-development
    source: f3

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

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)

Key Concepts

TTP Module Overview

Impersonation Protection Scenarios

• Hit 3 (Default): Flags emails matching 3+ impersonation indicators
• Hit 1 (VIP): Flags emails matching 1+ indicator for designated VIP users
• Key identifiers: display name similarity, domain similarity, reply-to mismatch, newly registered domains

URL Protect Modes

• Rewrite: URLs rewritten to route through Mimecast proxy at click time
• Pre-Delivery Action (Hold): URLs checked before message delivery; held if suspicious
• Pre-Delivery Action (None): URLs checked pre-delivery but not held

Workflow

Step 1: Configure URL Protect Policy

• Navigate to Administration > Gateway > Policies > Targeted Threat Protection - URL Protect
• Create URL Protect definition with rewriting enabled for inbound messages
• Enable URL Pre-Delivery Action set to "Hold" for maximum protection
• Configure scan mode: aggressive for high-risk users, moderate for general population
• Set action for malicious URLs: block page with user notification
• Enable URL logging for all click events

Step 2: Configure Attachment Protect Policy

• Navigate to Administration > Gateway > Policies > Targeted Threat Protection - Attachment Protect
• Create Attachment Protect definition for inbound email
• Select sandbox mode: "Safe File" (converts to safe format) or "Dynamic Configuration" (full sandbox)
• Configure attachment types to scan: executables, Office documents, PDFs, archives
• Set timeout for sandbox analysis (default: up to 7 minutes for complex files)
• Enable pre-emptive sandboxing for attachments from unknown senders

Step 3: Configure Impersonation Protect

• Create Default Impersonation Protect Definition (Hit 3) for all inbound email
• Create VIP Impersonation Protect Definition (Hit 1) for executive protection
• Build VIP list: CEO, CFO, CTO, board members, finance leadership
• Configure detection identifiers: display name, domain similarity, newly observed sender
• Set actions: quarantine high-confidence impersonation, tag moderate confidence
• Enable end-user warning banners for flagged messages

Step 4: Enable Internal Email Protect

• Configure journaling from Microsoft 365/Google Workspace to Mimecast
• Enable URL scanning for internal emails
• Enable attachment scanning for internal emails
• Configure alerts for internal account compromise indicators
• Set up detection for internal phishing (compromised account sending malware)

Step 5: Create Test Group and Validate

• Create pilot group of 50-100 users across departments
• Apply TTP policies to pilot group first
• Send test emails with known-safe test URLs and EICAR test files
• Verify URL rewriting, attachment sandboxing, and impersonation detection
• Monitor false positive rate for 1-2 weeks before organization-wide deployment

Step 6: Deploy Organization-Wide and Tune

• Extend TTP policies to all users
• Monitor Mimecast Threat Dashboard for detection metrics
• Review and whitelist legitimate applications triggering false positives
• Tune impersonation sensitivity based on false positive feedback
• Configure exception policies for automated systems and mailing lists

Tools & Resources

• Mimecast Administration Console: Policy configuration and management
• Mimecast Threat Dashboard: Real-time threat visibility and analytics
• Mimecast Awareness Training: Integrated security awareness platform
• Mimecast API: Programmatic access to logs and threat data
• Message Center: Quarantine management for admins and users

Validation

• URL Protect rewrites URLs in test messages and blocks known-malicious at click
• Attachment Protect sandboxes test file and returns verdict within SLA
• Impersonation Protect flags test BEC email impersonating VIP
• Internal Email Protect detects test lateral phishing scenario
• Pre-delivery hold catches weaponized URL before reaching inbox
• False positive rate below organizational threshold after tuning

Other files in this skill

• LICENSE
• assets/template.md
• references/api-reference.md
• references/standards.md
• references/workflows.md
• scripts/agent.py
• scripts/process.py

assets/template.md (verbatim)

Mimecast Targeted Threat Protection Deployment Template

TTP Policy Configuration

VIP List for Impersonation Protect

Deployment Phases

• Phase 1: Configure URL Protect (pilot group)
• Phase 2: Configure Attachment Protect (pilot group)
• Phase 3: Configure Impersonation Protect with VIP list
• Phase 4: Enable Internal Email Protect via journaling
• Phase 5: Roll out to all users
• Phase 6: Tune policies based on false positive feedback

Validation Checklist

• URL Protect rewrites links in test email
• URL Pre-delivery Hold stops weaponized link
• Attachment Protect sandboxes EICAR test file
• Impersonation Protect flags test BEC email
• Internal Email Protect detects test internal phishing
• Threat Dashboard shows detection metrics

references/api-reference.md (verbatim)

API Reference: Implementing Mimecast Targeted Attack Protection

Mimecast API Authentication

import requests
headers = {"Authorization": "MC access_key:secret_key",
           "x-mc-app-id": "app-id"}
resp = requests.post("https://us-api.mimecast.com/api/ttp/url/get-logs",
                     headers=headers, json={"data": [{"from": "2024-01-01"}]})

TTP API Endpoints

URL Protection Actions

Attachment Sandbox Results

Impersonation Types

References

• Mimecast API: https://developer.services.mimecast.com/
• TTP URL Protection: https://developer.services.mimecast.com/docs/threatsintel/1/routes/ttp/url/get-logs/post

references/standards.md (verbatim)

Standards & References: Implementing Mimecast Targeted Attack Protection

MITRE ATT&CK References

• T1566.001: Phishing: Spearphishing Attachment
• T1566.002: Phishing: Spearphishing Link
• T1534: Internal Spearphishing
• T1598: Phishing for Information
• T1656: Impersonation
• T1204.001: User Execution: Malicious Link
• T1204.002: User Execution: Malicious File

Mimecast TTP Components

Compliance Alignment

• CIS Controls v8 Control 9.2: Use DNS filtering services
• CIS Controls v8 Control 9.6: Block unnecessary file types
• NIST SP 800-177: Trustworthy Email
• SOC 2 CC6.1: Logical and physical access controls
• ISO 27001 A.8.23: Web filtering

Impersonation Protection Indicators

Integration Points

• Microsoft 365 via connector and journaling
• Google Workspace via gateway routing
• SIEM via syslog or API (Splunk, QRadar, Sentinel)
• SOAR platforms via Mimecast API
• Directory sync via Active Directory / Azure AD

references/workflows.md (verbatim)

Workflows: Implementing Mimecast Targeted Attack Protection

Workflow 1: URL Protect Processing

Inbound email with URLs arrives
  |
  v
[Pre-delivery URL check]
  +-- Extract all URLs from body and attachments
  +-- Check against Mimecast threat intelligence
  +-- KNOWN MALICIOUS --> Hold/Block message
  +-- SUSPICIOUS --> Hold for deeper analysis
  +-- CLEAN --> Proceed to rewriting
  |
  v
[URL rewriting]
  +-- Replace original URLs with Mimecast proxy URLs
  +-- Preserve original URL in encoded format
  +-- Apply per-policy rewriting rules
  |
  v
[Message delivered to user inbox]
  |
  v
[User clicks rewritten URL]
  |
  v
[Time-of-click analysis]
  +-- Real-time page scan and sandbox
  +-- Check for credential harvesting forms
  +-- Check for malware downloads
  |
  v
[Decision]
  +-- SAFE: Redirect to original URL
  +-- MALICIOUS: Display block page
  +-- SUSPICIOUS: Display warning with proceed option

Workflow 2: Attachment Protect Pipeline

Email with attachment arrives
  |
  v
[Static analysis]
  +-- File type identification
  +-- Signature matching
  +-- Known malware hash check
  |
  v
[Policy evaluation]
  +-- Safe File mode: Convert to safe format (PDF)
  +-- Dynamic mode: Full sandbox detonation
  +-- Bypass: Whitelisted sender/type
  |
  v
[Dynamic sandbox (if configured)]
  +-- Execute in isolated environment
  +-- Monitor for malicious behavior
  +-- Check for C2 callbacks, file drops, registry changes
  +-- Timeout: up to 7 minutes
  |
  v
[Verdict]
  +-- CLEAN: Deliver original attachment
  +-- MALICIOUS: Quarantine, notify admin
  +-- TIMEOUT: Deliver with warning or hold per policy

Workflow 3: Impersonation Protect Analysis

Inbound email arrives
  |
  v
[Identifier check against VIP list]
  +-- Compare display name to VIP names
  +-- Check domain similarity to internal domains
  +-- Verify reply-to alignment
  +-- Check if sender is newly observed
  |
  v
[Hit scoring]
  +-- Hit 1 policy (VIP): 1+ indicator match
  +-- Hit 3 policy (Default): 3+ indicator matches
  |
  v
[Action based on hit level]
  +-- QUARANTINE: High confidence impersonation
  +-- TAG: Moderate confidence, add warning banner
  +-- LOG: Low confidence, record for analysis
  +-- DELIVER: No indicators matched

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