Security Incident Response for Startups

May 23, 2016

Security incidents aren’t a matter of if, but when. Even well-defended organizations experience breaches, compromises, and security events that require rapid response. For startups, the question isn’t whether you’ll face an incident—it’s whether you’ll be prepared when it happens.

Most startups I work with have no incident response plan. When something goes wrong, they improvise: engineers panic-scrambling to understand what happened, executives unsure what to communicate, and no clear process for containment or recovery. The result is extended damage, poor communication, and preventable reputation harm.

You don’t need an enterprise security team to have an incident response plan. You need to think through scenarios before they happen and document basic procedures. Here’s how.

What Constitutes an Incident

First, define what you’re responding to. Not every security event is an incident requiring full response.

Security events: Unusual activity that might indicate a problem. Failed login attempts, unusual traffic patterns, suspicious log entries. Investigate these, but they don’t necessarily require incident response.

Security incidents: Confirmed or highly suspected compromise requiring immediate action. Unauthorized access to systems, data exfiltration, malware infection, credential theft.

The line between event and incident involves judgment. When uncertain, err toward treating it as an incident. You can downgrade after investigation; you can’t undo delayed response to a real incident.

The Response Team

Identify who’s involved in incident response before you need them.

Core Roles

Incident Commander: Single point of decision-making authority. This person coordinates response, makes judgment calls, and ensures communication happens. Usually a senior engineer or CTO for technical incidents.

Technical Lead: Drives technical investigation and remediation. Coordinates technical resources, directs forensic analysis, implements containment.

Communications Lead: Handles internal and external communication. Coordinates with legal, drafts customer notifications, manages public statements.

For a small startup, one person might fill multiple roles. But clearly designate who owns which responsibilities—ambiguity during incidents costs time.

Contact Information

Document how to reach everyone:

Test contact information periodically. Phone numbers change; people leave; contact lists rot.

Incident Phases

Structure your response into phases. Each phase has different goals and activities.

Phase 1: Detection and Triage

Goal: Confirm an incident is occurring and assess severity.

When a potential incident is reported:

  1. Gather initial information: What was observed? When? By whom? What systems are affected?

  2. Assess severity: Use a simple scale:

    • Critical: Active exfiltration, production systems compromised, customer data at risk
    • High: Confirmed unauthorized access, significant system compromise
    • Medium: Suspected compromise, limited scope
    • Low: Security event requiring investigation, unclear impact

  3. Activate response: For critical and high severity, immediately activate the incident response team. For medium and low, the person on-call may investigate before escalating.

Phase 2: Containment

Goal: Stop the bleeding. Limit the incident’s scope and prevent further damage.

Containment strategies depend on the incident type:

Account compromise: Revoke credentials immediately. Reset passwords for affected accounts. Revoke API keys and tokens. Review recent activity from the compromised account.

Server compromise: Isolate the affected system from the network. Don’t shut it down yet—you’ll lose volatile forensic data. Block network access while preserving the system for investigation.

Data breach: If exfiltration is ongoing, terminate the channel. This might mean blocking IP addresses, revoking access, or taking systems offline.

Malware: Isolate infected systems. Block command-and-control communication if identified. Don’t delete the malware yet—preserve it for analysis.

Containment involves tradeoffs. Taking systems offline stops the incident but causes service disruption. Make these decisions consciously, not reactively.

Phase 3: Investigation

Goal: Understand what happened, how, and the full extent of impact.

Investigation questions:

Investigation techniques:

Log analysis: Review authentication logs, application logs, network logs. Look for anomalous access patterns, unusual commands, data transfer spikes.

Forensic imaging: For compromised systems, create forensic images before modification. This preserves evidence and enables detailed analysis.

Timeline construction: Build a timeline of attacker activity. When did initial compromise occur? What sequence of actions followed?

Indicator collection: Document indicators of compromise (IOCs): IP addresses, malware hashes, account names. These help identify related activity and prevent reoccurrence.

Don’t rush investigation to restore service. Incomplete understanding leads to incomplete remediation.

Phase 4: Eradication

Goal: Remove the attacker’s access and persistence mechanisms.

Based on investigation findings:

Verify eradication is complete. Attackers often establish multiple persistence mechanisms; missing one means they return.

Phase 5: Recovery

Goal: Restore normal operations safely.

Recovery steps:

  1. Rebuild from known-good state: When possible, rebuild compromised systems from trusted sources (fresh OS installation, configuration from version control) rather than cleaning infected systems.

  2. Restore from backups: If data was corrupted or deleted, restore from backups created before the compromise.

  3. Gradual restoration: Bring systems back incrementally. Monitor closely for signs of recompromise.

  4. Verification: Confirm systems are functioning correctly and the incident hasn’t recurred.

Phase 6: Lessons Learned

Goal: Improve defenses and response capabilities.

Within a week of incident closure, conduct a blameless retrospective:

Document findings. Implement improvements. Update this playbook.

Communication

Incidents require careful communication internally, externally, and potentially with regulators.

Internal Communication

Keep the organization informed without creating panic:

External Communication

For incidents affecting customers or partners:

Regulatory Notification

Depending on your industry and the data involved, you may have legal obligations to notify regulators. HIPAA, PCI-DSS, and GDPR all have notification requirements. Know which regulations apply to you before an incident occurs.

Documentation

Document throughout the incident:

Documentation serves multiple purposes: legal protection, regulatory compliance, learning, and handoff between responders.

Use a shared document or incident management system. Don’t rely on memory or scattered chat logs.

Preparation Activities

Incident response improves with preparation. Before your next incident:

Inventory Critical Assets

Know what you’re protecting:

Establish Monitoring

You can’t respond to incidents you don’t detect:

Prepare Communication Templates

Draft communication templates before you need them:

Templates need customization for specific incidents, but starting from a template saves time and ensures completeness.

Practice

Tabletop exercises walk through scenarios without touching real systems. Gather your response team and work through: “What would we do if…?”

Discussion reveals gaps in your plan before real incidents expose them.

Conclusion

Incident response planning isn’t paranoia—it’s professionalism. Every startup faces security incidents eventually. The difference between organizations that survive incidents with minimal damage and those that suffer extensively often comes down to preparation.

Create your first incident response playbook this week. It doesn’t need to be perfect; it needs to exist. You can refine it over time, informed by practice and experience. But you can’t create a playbook during an incident—by then, it’s too late.

Key Takeaways