How to Control Attack Surface with Incident Response

How to Control Attack Surface with Incident Response

Controlling the attack surface with Incident Response (IR) means reducing exploitable entry points while simultaneously preparing to respond quickly when a threat actor attempts or succeeds in breaching defenses.

Here’s a structured Controlled Attack Surface with Incident Response (IR) Plan:

1. Preparation: Shrink the Attack Surface

Before an incident occurs, IR teams work with security engineering and IT to minimize exposure.

• Asset inventory: Identify all devices, apps, services, and shadow IT.
• Patch & vulnerability management: Continuously patch known CVEs and remove unsupported systems.
• Access control: Enforce MFA, least privilege, and role-based access.
• Network segmentation: Limit lateral movement with micro-segmentation and VLANs.
• Hardening: Disable unused ports, protocols, and services.
• Attack surface monitoring: Use ASM tools to discover exposed endpoints (internal & external).

2. Detection: Spot Attack Surface Exploitation

IR teams should be able to quickly detect when the attack surface is being abused.

• Monitor logs and network flows (via SIEM, NDR, EDR).
• Detect reconnaissance activity (scanning, unusual authentication attempts, web probes).
• Threat intel correlation: Match indicators against known vulnerabilities.
• User behavior monitoring: Spot abnormal privilege escalations or credential use.

3. Containment: Limit the Attacker’s Reach

When an incident occurs, control the attack surface in real-time by reducing what the attacker can access.

• Network isolation: Block or quarantine compromised endpoints.
• Account lockdown: Disable or reset compromised accounts.
• Kill malicious processes on endpoints.
• Block malicious domains/IPs via firewall/DNS filtering.
• Restrict movement by tightening security group rules in cloud environments.

4. Eradication & Recovery: Restore Secure Surfaces

• Remove persistence mechanisms (malware, backdoors, rogue accounts).
• Apply missing patches or security fixes.
• Re-image systems if needed to ensure no hidden implants.
• Credential resets for affected users/systems.
• Reinforce security controls identified as weak points.

5. Post-Incident: Improve Surface Control

• Root cause analysis: Determine how the attack surface was exploited.
• Update playbooks with new attack patterns.
• Close security gaps: Shut down exposed services, review firewall rules, fix misconfigurations.
• Continuous hardening: Integrate lessons learned into vulnerability and configuration management.
• Purple teaming: Test whether changes effectively reduce attack surface.

How IR Controls Attack Surface

• Before incidents → Proactively shrink exposure (patching, segmentation, access control).
• During incidents → Limit attacker mobility by dynamically reducing available surface.
• After incidents → Harden defenses and feed back into preventive measures.

This framework ensures that reducing the attack surface and having a strong Incident Response plan work hand-in-hand to minimize both the likelihood of compromise and the impact of incidents.