SOC Playbook: Compromised Account Investigation

In today's digital landscape, compromised accounts pose a significant threat to organisations, often leading to data breaches, financial loss, and reputational damage. This SOC playbook outlines a systematic approach for investigating compromised user accounts, focusing on identity security. The playbook is designed for security operations teams to effectively manage high-severity incidents involving compromised accounts, ensuring a thorough response and minimising the impact on the organisation.

Introduction — What incident does this playbook address?

This playbook addresses incidents involving compromised user accounts, which can occur through various vectors such as phishing, credential stuffing, or exploitation of weak passwords. The severity of such incidents is classified as high due to the potential for initial access, persistence within the network, and lateral movement to other critical assets. A well-defined response plan is essential for identifying, containing, and eradicating threats associated with compromised accounts.

Detection & Triage — Initial indicators and severity assessment

The first step in the incident response process is detection and triage. Security teams should monitor for specific indicators that suggest a compromised account, including:

• Unusual login activity: Logins from unfamiliar IP addresses or geographical locations.
• Multiple failed login attempts: A sudden spike in failed logins may indicate credential stuffing attempts.
• Account activity anomalies: Unusual actions taken by the account, such as changes to settings, password resets, or access to sensitive data not typically associated with the user.
• Alerts from security tools: Notifications from SIEM (Security Information and Event Management) systems or identity protection tools that flag suspicious behaviour.

Upon detecting these indicators, the severity of the incident should be assessed based on the potential impact on the organisation. Factors to consider include the sensitivity of the data accessed, the role of the compromised account, and any evidence of lateral movement within the network. High-severity incidents should trigger an immediate escalation to the incident response team.

Investigation Steps — Detailed analysis procedure

Once an incident has been triaged, a thorough investigation is essential to understand the scope and impact of the compromise. The investigation should follow these steps:

1. Collect evidence: Gather logs from various sources, including authentication logs, application logs, and network traffic data. Ensure that evidence is collected in a forensically sound manner to maintain integrity.

2. Identify the attack vector: Determine how the account was compromised. This may involve examining phishing emails, malware infections, or vulnerabilities exploited by attackers.

3. Assess lateral movement: Investigate whether the attacker has moved laterally within the network. This can be done by reviewing logs for unusual access patterns, such as attempts to access other user accounts or sensitive systems.

4. Check for persistence mechanisms: Identify any methods the attacker may have used to maintain access, such as creating new user accounts, installing backdoors, or modifying system configurations.

5. Document findings: Maintain a detailed record of all findings, including timelines of events, affected systems, and any indicators of compromise (IOCs) that can assist in future investigations.

Containment & Eradication — How to stop and remove the threat

Once the investigation is complete, the next phase is containment and eradication. The following actions should be taken:

1. Isolate the compromised account: Temporarily disable the account to prevent further unauthorised access. This may involve suspending the account or enforcing multi-factor authentication (MFA) for additional verification.

2. Remove persistence mechanisms: If any backdoors or unauthorised accounts have been created, they should be removed immediately. Conduct a thorough review of system configurations to ensure no lingering threats remain.

3. Change credentials: Force a password reset for the compromised account and any accounts that may have been accessed by the attacker. Ensure that new passwords meet strong complexity requirements.

4. Implement additional security measures: Strengthen security controls by enabling MFA across all accounts, enforcing stricter access controls, and deploying endpoint detection and response (EDR) solutions to monitor for suspicious activity.

Recovery — Restoring normal operations

After containment and eradication, the focus shifts to recovery. This involves restoring normal operations while ensuring that the threat has been fully addressed:

1. Monitor systems: Continue to monitor affected systems for any signs of residual threats. Use security tools to analyse logs and detect anomalies.

2. Communicate with stakeholders: Inform relevant stakeholders, including management and affected users, about the incident and the steps taken to resolve it. Transparency is key to maintaining trust.

3. Restore data and services: If any data was affected during the incident, ensure that backups are restored and services are brought back online securely.

4. Conduct a post-incident review: Assess the incident response process to identify any gaps or areas for improvement. This review should involve all stakeholders to gather insights and refine the response strategy.

Lessons Learned — Post-incident improvements and reporting

The final phase of the incident response process is to learn from the experience. Conducting a thorough post-incident analysis will help improve future responses and strengthen the organisation's security posture:

1. Document the incident: Create a comprehensive report detailing the incident, including the timeline, actions taken, and lessons learned. This documentation will serve as a valuable resource for future incidents.

2. Identify trends and patterns: Analyse the incident in the context of other security events to identify trends that may indicate systemic issues. This can inform future risk assessments and security improvements.

3. Update policies and procedures: Based on the findings from the incident, update incident response plans, security policies, and user training programmes to address identified weaknesses.

4. Conduct training: Use the incident as a case study for training sessions with staff to raise awareness about security best practices and the importance of vigilance in identifying potential threats.

In conclusion, a well-structured SOC playbook for compromised account investigations is crucial for organisations to effectively respond to high-severity incidents. By following this playbook, security teams can ensure a thorough investigation, containment, and recovery process, ultimately strengthening their identity security posture.

For further assistance in developing and implementing robust incident response strategies, contact CyberZonic today. Our team of cybersecurity experts is ready to help you safeguard your organisation against evolving threats.