About

Imported from mukul975/anthropic-cybersecurity-skills (skills/detecting-email-account-compromise/SKILL.md). Install upstream with npx skills add mukul975/anthropic-cybersecurity-skills --skill detecting-email-account-compromise. Copyright stays with the author (Apache-2.0).

Detecting Email Account Compromise

Name: detecting-email-account-compromise
Author: mukul975

Overview

Email account compromise (EAC) is a prevalent attack vector where adversaries gain unauthorized access to mailboxes to exfiltrate sensitive data, conduct business email compromise (BEC), or establish persistence through inbox rule manipulation. Attackers commonly create forwarding rules to siphon emails, delete rules to hide evidence, or use OAuth tokens for persistent access. Detection relies on analyzing Microsoft 365 Unified Audit Logs, Azure AD sign-in logs for impossible travel or suspicious locations, inbox rule creation events (Set-InboxRule, New-InboxRule), and Microsoft Graph API access patterns. Key indicators include forwarding rules to external addresses, rules that delete or move messages matching keywords like "invoice" or "payment", and sign-ins from unusual user agents such as python-requests.

When to Use

When investigating security incidents that require detecting email account compromise
When building detection rules or threat hunting queries for this domain
When SOC analysts need structured procedures for this analysis type
When validating security monitoring coverage for related attack techniques

Prerequisites

Microsoft 365 with Unified Audit Logging enabled
Azure AD P1/P2 for risk detection APIs
Python 3.9+ with requests, msal libraries
Microsoft Graph API application registration with Mail.Read, AuditLog.Read.All permissions
Understanding of OAuth2 client credential flows

Steps

Export audit logs or connect to Microsoft Graph API using MSAL authentication
Query inbox rules for all monitored mailboxes via /users/{id}/mailFolders/inbox/messageRules
Analyze rules for external forwarding (ForwardTo, RedirectTo external addresses)
Detect suspicious rule patterns: deletion rules, keyword-matching rules targeting financial terms
Query sign-in logs via /auditLogs/signIns for unusual locations and impossible travel
Check for suspicious user agent strings (python-requests, PowerShell, curl)
Identify OAuth application consent grants for suspicious third-party apps
Correlate findings across users to detect campaign-level compromise
Generate compromise indicators report with severity scores

Expected Output

A JSON report listing compromised or suspicious accounts, malicious inbox rules detected, impossible travel events, suspicious OAuth grants, and recommended containment actions with severity ratings.

Use it

Copy one of these into your project. Installing also returns the manifest and these snippets.

yaml

targets:
  - https://api.opensmartroute.ai/api/v1/registry/mukul975-anthropic-cybersecurity-skills-detecting-email-85f8a4/manifest   # or paste the manifest below

Manifest

An Open Capability Manifest: the router reads it to know what this does, what it costs and when to pick it.

mukul975-anthropic-cybersecurity-skills-detecting-email-85f8a4.ocm.jsonjson

{
  "ocm": "1",
  "id": "mukul975-anthropic-cybersecurity-skills-detecting-email-85f8a4",
  "kind": "skill",
  "name": "detecting-email-account-compromise",
  "description": "Detect compromised O365 and Google Workspace email accounts by analyzing Unified Audit Logs and Azure AD sign-in logs for impossible travel, inbox rule creation/deletion (Set-InboxRule, New-InboxRule), external mail forwarding rules, and unusual Microsoft Graph API access or OAuth token use. Use when investigating suspected business email compromise (BEC), account takeover, or mailbox persistence via malicious inbox rules.",
  "publisher": "mukul975",
  "version": "1.0.0",
  "capabilities": {
    "domains": [
      "coding"
    ],
    "tags": [
      "skill-md",
      "email-compromise",
      "office365",
      "microsoft-graph",
      "bec",
      "inbox-rules",
      "sign-in-analysis",
      "account-takeover",
      "skills-sh"
    ],
    "languages": [
      "en"
    ]
  },
  "quality_prior": 0.6,
  "examples": [
    "Detect compromised O365 and Google Workspace email accounts by analyzing Unified Audit Logs and Azure AD sign-in logs for impossible travel, inbox rule creation/deletion (Set-InboxRule, New-InboxRule), external mail forwarding rules, and unusual Microsoft Graph API access or OAuth token use. Use when investigating suspected business email compromise (BEC), account takeover, or mailbox persistence via malicious inbox rules."
  ],
  "primary": false,
  "metadata": {
    "source": {
      "provider": "skills.sh",
      "repository": "https://github.com/mukul975/anthropic-cybersecurity-skills",
      "path": "skills/detecting-email-account-compromise/SKILL.md",
      "ref": "HEAD",
      "url": "https://github.com/mukul975/anthropic-cybersecurity-skills/blob/HEAD/skills/detecting-email-account-compromise/SKILL.md",
      "key": "mukul975/anthropic-cybersecurity-skills/skills/detecting-email-account-compromise/SKILL.md"
    },
    "license": "Apache-2.0"
  },
  "instructions": "# Detecting Email Account Compromise\n\n## Overview\n\nEmail account compromise (EAC) is a prevalent attack vector where adversaries gain unauthorized access to mailboxes to exfiltrate sensitive data, conduct business email compromise (BEC), or establish persistence through inbox rule manipulation. Attackers commonly create forwarding rules to siphon emails, delete rules to hide evidence, or use OAuth tokens for persistent access. Detection relies on analyzing Microsoft 365 Unified Audit Logs, Azure AD sign-in logs for impossible travel or suspicious locations, inbox rule creation events (Set-Inbo",
  "cost": {
    "context_tokens": 619
  }
}

Fetch it by URL: GET /api/v1/registry/mukul975-anthropic-cybersecurity-skills-detecting-email-85f8a4/manifest?version=1.0.0

Reviews

Star ratings from people who tried it. One review per account; edit yours any time.

No reviews yet. Install it, try it, and be the first to rate it.