OS Credential Dumping: Detection, Defence, and Mitigation

OS Credential Dumping: Detection, Defence, and Mitigation

In today's cyber landscape, the extraction of credentials from operating systems, known as OS Credential Dumping, has emerged as a critical threat. This technique, classified under the MITRE ATT&CK framework as T1003, is used by attackers to gain unauthorised access to systems, escalate privileges, and move laterally within networks. Understanding how this threat operates and implementing effective detection and mitigation strategies is essential for security teams to safeguard their environments.

How It Works

OS Credential Dumping involves extracting sensitive credential material from various sources within an operating system. Attackers typically target:

• Operating System Memory: The Local Security Authority Subsystem Service (LSASS) process is a primary target. It stores user credentials in memory, making it a lucrative source for attackers.
• Registry Hives: Credentials can also be found in Windows registry hives, particularly under the SAM (Security Account Manager) and SYSTEM hives.
• Directory Services Databases: Active Directory (AD) databases can be accessed to retrieve credentials for domain accounts.

The attack often begins with an initial compromise, where an attacker gains access to a system through phishing, exploitation, or other means. Once inside, they may execute commands to access the LSASS process, leveraging tools like Mimikatz or built-in Windows utilities (e.g., procdump) to create memory dumps. The creation of LSASS memory dump files (*.dmp) in user-accessible directories is a common tactic used to extract credentials.

Additionally, attackers may create Volume Shadow Copies on domain controllers outside of scheduled backups, allowing them to capture sensitive data without detection. This technique can significantly enhance their ability to perform lateral movement across the network.

Detection

Identifying OS Credential Dumping activities requires vigilant monitoring of specific logs and events. Key indicators include:

• Process Access Events Targeting LSASS: Monitor Sysmon Event ID 10, which logs process access events. Look for access masks that indicate attempts to read the LSASS process (e.g., access mask 0x1010).
• Creation of LSASS Memory Dumps: Investigate any instances of LSASS memory dump files (*.dmp) being created in user-accessible directories. This could indicate an attempt to extract credentials.
• Volume Shadow Copy Creation: Track the creation of Volume Shadow Copies on domain controllers, especially if they occur outside of normal backup schedules. This may signal an attempt to capture sensitive data.

Implementing a Security Information and Event Management (SIEM) solution can facilitate the aggregation and analysis of these logs, enabling rapid detection of suspicious activities.

Mitigation

To defend against OS Credential Dumping, organisations should adopt a multi-layered approach that includes the following measures:

1. Enable Windows Credential Guard: This feature isolates the LSASS process in a virtualised container, making it more difficult for attackers to access credentials stored in memory.

2. Restrict Debug Privileges: Limit the SeDebugPrivilege to essential administrative accounts only. This reduces the risk of unauthorised users accessing sensitive processes like LSASS.

3. Deploy Protected Users Security Group: For high-value domain accounts, consider deploying the Protected Users security group. This group enforces additional security measures, including restrictions on credential caching and the use of NTLM authentication.

4. Implement Application Control: Use application control solutions to prevent unauthorised tools (e.g., Mimikatz) from executing on endpoints.

5. Regularly Update and Patch Systems: Ensure that all systems are regularly updated to mitigate vulnerabilities that could be exploited for credential dumping.

Recommended Actions

In the event of a suspected OS Credential Dumping attack, security teams should follow this step-by-step response plan:

1. Immediate Containment:

   • Isolate affected systems from the network to prevent further lateral movement.
   • Disable accounts that may have been compromised.

2. Investigation:

   • Review Sysmon logs for suspicious process access events targeting LSASS.
   • Check for any LSASS memory dump files created in user-accessible directories.
   • Investigate any unusual Volume Shadow Copy creations on domain controllers.

3. Remediation:

   • Remove any identified malicious tools or scripts from the environment.
   • Change passwords for compromised accounts and consider implementing multi-factor authentication (MFA).

4. Post-Incident Review:

   • Conduct a thorough analysis of the incident to identify how the breach occurred.
   • Update incident response plans and security policies based on lessons learned.

5. Continuous Monitoring:

   • Enhance monitoring capabilities to detect future credential dumping attempts.
   • Regularly review and update detection rules in your SIEM solution.

By implementing these detection and mitigation strategies, organisations can significantly reduce the risk of OS Credential Dumping and bolster their overall security posture.

For tailored guidance and support in fortifying your cybersecurity measures against OS Credential Dumping and other threats, contact CyberZonic today. Our team of experts is ready to assist you in enhancing your security framework and safeguarding your critical assets.