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Office 365 監査ログ分析による不正アクセス検知

Microsoft Graph API を介して Office 365 統合監査ログを解析し、ビジネスメール詐欺 (BEC) などの侵害兆候を検出します。

Office 365 監査ログ分析による不正アクセス検知 とは？

このスキルは、Office 365 統合監査ログを Microsoft Graph API でクエリし、ビジネスメール詐欺 (BEC) 攻撃の痕跡（不審な受信トレイルールの作成、外部転送設定、メールボックス委任の変更、不正な OAuth アプリ同意）を検出するための手順を提供します。SOC アナリストやセキュリティエンジニアが、侵害指標 (IOC) を体系的に調査し、タイムライン付きのレポートを生成できるように設計されています。前提条件として、Azure AD アプリ登録（AuditLog.Read.All 等の権限）と Python 3.9 以上が必要です。このスキルは、Microsoft Graph API と MSAL 認証を利用し、JSON 形式でリスクスコア付きのレポートを出力します。

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ドキュメント

Office 365 監査ログ分析による不正アクセス検知 は何をしますか？

概要

ビジネスメール詐欺 (BEC) 攻撃は、Office 365 の監査ログに痕跡を残すことがよくあります。不審な受信トレイルールの作成、外部アドレスへのメール転送、メールボックス委任の変更、不正な OAuth アプリケーション同意などです。このスキルは、Microsoft Graph API を使用して統合監査ログをクエリし、メールボックス全体の受信トレイルールを列挙し、転送設定を検出し、侵害されたアカウントの兆候を特定します。

使用するタイミング

  • Office 365 監査ログを分析して不正アクセスを調査するセキュリティインシデント対応時
  • このドメイン向けの検出ルールや脅威ハンティングクエリを作成する場合
  • SOC アナリストがこの分析タイプの構造化された手順を必要とする場合
  • 関連する攻撃手法に対するセキュリティ監視のカバレッジを検証する場合

前提条件

  • Azure AD アプリ登録: AuditLog.Read.All、MailboxSettings.Read、Mail.Read (アプリケーションアクセス許可)
  • Python 3.9+ と msal、requests
  • 認証用のクライアントシークレットまたは証明書
  • 全体閲覧者またはセキュリティ閲覧者のロール

手順

  1. MSAL クライアント資格情報フローを使用して Microsoft Graph に認証する
  2. 不審な操作 (Set-Mailbox、New-InboxRule) について統合監査ログをクエリする
  3. メールボックス全体の受信トレイルールを列挙し、転送ルールをフラグ付けする
  4. メールボックス委任の変更 (Add-MailboxPermission) を検出する
  5. 不審なアプリケーションへの OAuth 同意を特定する
  6. 監査ログから不審なサインインパターンを確認する
  7. タイムライン付きの侵害指標レポートを生成する

期待される出力

  • 転送ルール、委任の変更、OAuth 同意、リスクスコア付きの不審な監査イベントをリストした JSON レポート
  • 影響を受けるメールボックスと共に侵害指標のタイムライン

Individual skills in this repo

This repo contains 20 individual skills — each has its own dedicated page.

abusing-dpapi-for-credential-access

Extract and decrypt Windows DPAPI-protected secrets (Credential Manager, browser logins/cookies, Wi-Fi credentials, KeePass keys) online or offline using SharpDPAPI, SharpChrome, Mimikatz, or Impacket

abusing-shadow-credentials-for-privesc

Take over Active Directory accounts by writing attacker-controlled public keys to msDS-KeyCredentialLink (Shadow Credentials) with pyWhisker, Whisker, or Certipy, then authenticate via PKINIT to recover the target

achieving-cmmc-level-2-compliance

>-

acquiring-disk-image-with-dd-and-dcfldd

Create forensically sound bit-for-bit disk images with dd or dcfldd on a Linux forensic workstation, preserving evidence integrity through hash verification (MD5/SHA) during acquisition. Use when imaging a suspect drive, USB device, or memory card for investigation, preserving volatile disk evidence during incident response, or producing a verified copy for legal or law-enforcement proceedings before any destructive analysis.

analyzing-active-directory-acl-abuse

Detect dangerous ACL misconfigurations in Active Directory using ldap3

analyzing-android-malware-with-apktool

Perform static analysis of Android APK malware using apktool for resource decompilation, jadx for Java source recovery, and androguard for manifest inspection, dangerous permission-combination detection, and identification of obfuscated code, dynamic code loading, and reflection-based API calls. Use to statically triage a suspicious APK without executing it or to build mobile malware detection rules.

analyzing-api-gateway-access-logs

Parses API Gateway access logs (AWS API Gateway, Kong, Nginx) to detect

analyzing-apt-group-with-mitre-navigator

Query ATT&CK data with attackcti, mitreattack-python, and stix2, then build MITRE ATT&CK Navigator layers and multi-layer heatmap overlays mapping one or more APT groups

analyzing-azure-activity-logs-for-threats

Queries Azure Monitor activity logs and sign-in logs via azure-monitor-query

analyzing-bootkit-and-rootkit-samples

Analyzes bootkit and advanced rootkit malware infecting the Master

analyzing-browser-forensics-with-hindsight

Parse Chromium-based browser databases with Hindsight to extract and correlate browsing history, downloads, cookies, cached content, autofill data, saved passwords, and extensions from Chrome, Edge, Brave, Opera, and Vivaldi into a unified timeline (XLSX, JSON, or SQLite output). Use during incident response, insider-threat investigations, or criminal cases when you need to reconstruct a user

analyzing-campaign-attribution-evidence

Systematically evaluate cyber-campaign evidence to attribute an operation to a threat actor, using the Diamond Model and Analysis of Competing Hypotheses (ACH) to weigh infrastructure overlaps, TTP consistency, malware code similarity, and timing/language artifacts into confidence-weighted attribution assessments. Use when an incident investigation needs a defensible attribution confidence level.

analyzing-certificate-transparency-for-phishing

Monitor Certificate Transparency logs using crt.sh and Certstream to

analyzing-cloud-storage-access-patterns

Detect abnormal access in AWS S3, GCS, and Azure Blob Storage by analyzing CloudTrail Data Events, GCS audit logs, and Azure Storage Analytics for after-hours bulk downloads, new-IP access, and API-call spikes (e.g. GetObject) via statistical baselines and time-series anomaly detection. Use when investigating suspected cloud data exfiltration or building related detection rules.

analyzing-cobalt-strike-beacon-configuration

Extract and analyze Cobalt Strike beacon configuration from PE files

analyzing-cobaltstrike-malleable-c2-profiles

Parse and analyze Cobalt Strike Malleable C2 profiles with dissect.cobaltstrike (profiles and beacon-payload configs) and pyMalleableC2 (AST parsing) to extract HTTP/DNS transforms, URIs, headers, sleep/jitter, and injection behavior, then generate network detection signatures. Use when reverse-engineering a captured malleable profile or building detections against Cobalt Strike Beacon traffic.

analyzing-command-and-control-communication

Analyzes malware C2 communication over HTTP, HTTPS, DNS, and custom

analyzing-cyber-kill-chain

Analyzes intrusion activity against the Lockheed Martin Cyber Kill Chain

analyzing-disk-image-with-autopsy

Perform comprehensive forensic analysis of raw (dd), E01, or AFF disk images with Autopsy and The Sleuth Kit, recovering deleted files, examining metadata and embedded artifacts, keyword searching, and building investigation timelines with visual reports. Use for structured analysis of a forensic disk image or when stakeholders need visual reports from evidence.

analyzing-dns-logs-for-exfiltration

Analyzes DNS query logs to detect data exfiltration via DNS tunneling,

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