Implementing Email Sandboxing with Proofpoint
Overview
Email sandboxing detonates suspicious attachments and URLs in isolated environments to detect zero-day malware and evasive phishing payloads. Proofpoint Targeted Attack Protection (TAP) is an industry-leading solution that uses multi-stage sandboxing, URL rewriting, and predictive analysis. This skill covers configuring Proofpoint TAP, integrating with email flow, analyzing sandbox reports, and tuning detection policies.
When to Use
- When deploying or configuring implementing email sandboxing with proofpoint 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
- Proofpoint Email Protection license with TAP add-on
- Admin access to Proofpoint admin console
- Understanding of email delivery architecture (MX records, mail flow rules)
- SIEM integration capability
Key Concepts
Proofpoint TAP Capabilities
- Attachment sandboxing: Detonates files in virtual machines (Windows, macOS, Android)
- URL Defense: Rewrites URLs, detonates at time-of-click
- Threat Intelligence: Proofpoint's NexusAI threat intelligence integration
- TAP Dashboard: Real-time visibility into threats targeting the organization
- Campaign correlation: Groups related attacks into campaigns
- Very Attacked People (VAP): Identifies most-targeted individuals
Sandbox Evasion Techniques Detected
- Delayed execution (time-bomb malware)
- VM detection bypass
- User interaction requirements (click-to-enable macros)
- Sandbox-aware malware that checks for analysis environment
- Encrypted/password-protected attachments
- Multi-stage payloads with delayed C2 retrieval
Workflow
Step 1: Configure TAP in Proofpoint
- Enable TAP for inbound email policy
- Configure sandbox profiles (attachment types to detonate)
- Set URL Defense rewriting policy
- Configure quarantine actions for malicious verdicts
Step 2: Tune Attachment Policies
Recommended attachment policy:
- Detonate: .exe, .dll, .scr, .doc(m), .xls(m), .ppt(m), .pdf, .zip, .rar, .7z, .iso
- Block without detonation: .bat, .cmd, .ps1, .vbs, .js, .wsf, .hta
- Password-protected archives: Attempt common passwords, then quarantine
- Dynamic delivery: Deliver email body, hold attachment until verdict
Step 3: Configure URL Defense
- Enable URL rewriting for all inbound email
- Set time-of-click detonation
- Block access to malicious URLs
- Show warning page for suspicious (not confirmed malicious) URLs
- Configure allowed domains bypass list
Step 4: Set Up TAP Dashboard Monitoring
- Configure daily threat digest emails to security team
- Set up real-time alerts for targeted attacks
- Monitor VAP report for high-risk users
- Review campaign clusters for coordinated attacks
Step 5: Integrate with SIEM
- Configure syslog/API export to SIEM
- Create correlation rules for TAP alerts
- Set up automated response workflows
Tools & Resources
Validation
- Attachment detonation catches EICAR test file and macro-enabled document
- URL Defense rewrites and blocks known phishing URLs
- TAP Dashboard displays threat summary
- SIEM receives and alerts on TAP events
