The New Reality of Cloud Forensics
“73% of enterprise breaches now involve cloud app abuse – with Google Workspace appearing in 1 of every 3 investigations” — 2024 CrowdStrike Cloud Threat Report
Key Investigation Challenges
🔴 Noise Overload: 12,000+ daily events per user in Workspace Enterprise
🔴 Blind Spots: Only 29% of orgs monitor OAuth API call logs
🔴 Time Bombs: Median dwell time for cloud attackers is 142 days (vs 7 days for on-prem)
Critical Audit Logs You Can’t Ignore
1. Gmail & Chat: The Phishing Kill Chain
High-Value Events
| Event Type | Normal Frequency | Suspicious Pattern |
|---|---|---|
attachment_download |
Frequent | .EXE from marketing@ |
late_spam_classification |
Rare | Executives marked as spam |
room_member_added |
Moderate | Unknown external users |
Pro Tip: Cross-reference with VirusTotal API for real-time malware hashes
2. Admin Activity: Signs of Account Takeover
Authentication Events Worth Scrutinizing
✅ sensitive_action_allowed – Bypassed MFA
🚨 suspicious_programmatic_login – Headless browser access
💀 user_suspended(suspicious_activity) – After off-hours logins
Top 3 Attacker Persistence Tactics:
- Out-of-domain forwarding to protonmail.com
- 2-step verification removal at 3 AM local time
- Recovery email swaps to newly created aliases
3. Drive Forensics: Data Exfiltration Signals
Atomic Indicators
owner_changed→ Internal docs now owned by sales@competitor.comchange_shared_drive_membership→ Added foreign Google accountsscript_trigger_created→ Unauthorized AppScript executions
Automated Detection Rule:
<YAML>title: Ransomware Prep in Google Drive description: Mass file deletions before encryption events: - name: trash count: >50 within 1h file_types: [".docx", ".xlsx", ".pptx"] - name: download count: sudden spike
Google Takeout: The Silent Data Killer
Why This Keeps CISOs Awake
- 1 Takeout job = All Drive files + 10 years of emails
- Default enabled in 89% of Workspace tenants
- Leaves no local traces unlike physical theft
Detection Strategy:
- Baseline normal Takeout frequency (typically <5/mo per user)
- Alert on:
- Takeouts scheduled after working hours
- Consecutive export attempts
- External storage destination patterns
OAuth: The Hidden Backdoor
Investigating API Abuse
Critical api_call Patterns
⚠️ gmail.send from non-email apps
⚠️ drive.permissions.create for foreign domains
⚠️ admin.directory.user.update with new recovery emails
Real-World Example:
Microsoft 365 attacker used legitimate OAuth app with these permissions:
https://www.googleapis.com/auth/gmail.readonlyhttps://www.googleapis.com/auth/drive.metadata- Exfiltrated 17GB before detection
Next-Gen Investigation Tactics
1. Behavioral Analytics Approach
- UEBA rules for:
- Unusual geologin sequences (NY → London in 1h)
- After-hours API call bursts
- Velocity checks for mass sharing
2. Cloud-Native Forensics
- BigQuery integration for petabyte-scale log analysis
- Chronicle Looker dashboards visualizing attack paths
- GCP Workflows for auto-remediation playbooks
3. Countermeasures Checklist
🔒 Restrict Takeout with Context-Aware Access
🔒 Enforce OAuth app review in Security Center
🔒 Enable Enterprise License for full API logging
Free Investigator Resources
📥 [Download] Our Google Workspace Kill Chain Matrix with:
- 28 TTPs mapped to MITRE ATT&CK
- Pre-built SiEM correlation rules
- Live demo of advanced threat hunts
