What Makes AD Connect MSOL Users Vulnerable to Suspected DCSync Attacks
You are at risk because the MSOL_ account has special rights. These rights let it copy directory data. AD Connect gives this account these rights. This helps it sync changes between your local Active Directory and Azure AD.
1. AD Connect picks which MSOL_ account to use for syncing.
2. It looks for missing rights and helps you add them.
3. The tool shows you how to set up rights for things like password sync and Exchange Hybrid.
This setup can cause a Suspected DCSync Attack alert. Sometimes, this alert is not real. You need to know how to spot normal activity and real danger.
Key Takeaways
The MSOL_ account has special rights to copy data between local Active Directory and Azure AD. This can set off Suspected DCSync Attack alerts.
Not all DCSync alerts are dangerous. Many are false alarms from normal AD Connect syncing on member servers.
Member servers with AD Connect can be risky. Attackers might use the MSOL_ account’s rights to steal important data.
Give MSOL_ accounts only the permissions they need. Check often and take away extra replication rights.
Watch replication requests carefully. Use strong security tools. Respond fast to alerts to keep your directory safe from real DCSync attacks.
Suspected DCSync Attack Alerts
What Triggers the Alert
You might wonder why a Suspected DCSync Attack alert shows up. Microsoft Defender for Identity and AATP look for strange actions. These tools watch for requests that copy directory data. They notice if these requests come from computers that are not domain controllers. If a computer tries to copy directory objects without the right permissions, it looks odd to the system.
Alerts happen when machines without permission try to copy data.
Clients copying directory objects without rights get noticed.
The alert is called DirectoryServicesRogueReplicationSecurityAlert and is very serious.
Logs can show a member server, not a domain controller, sending changes.
This alert helps you find people trying to steal important data like password hashes. You should always check carefully when you see a Suspected DCSync Attack alert.
False Positives and Exclusions
Not every Suspected DCSync Attack alert means there is real danger. Sometimes, normal things can look risky. Azure AD Connect uses MSOL_ user accounts to sync your Active Directory with Azure AD. This syncing usually happens on a member server, not a domain controller. When the MSOL_ account copies data, your security tools might think it is an attack.
MSOL_ accounts often cause false alarms.
This is normal and part of how AD Connect works.
You should check these alerts to know if they are real or safe.
If you see these alerts from your AD Connect server, you can change your security settings. You can exclude the server or account from this alert. This helps stop extra warnings but still keeps your system safe.
MSOL User Risks
Replication Permissions
It is important to know what permissions the MSOL_ account gets with AD Connect. These permissions let the account read and copy important data from Active Directory. AD Connect gives these rights so it can sync changes between your local AD and Azure AD. The table below lists the main permissions for the MSOL_ account:
These permissions are needed for AD Connect to work right. The MSOL_ account must see changes in your directory and copy them to Azure AD. If you use Password Hash Sync, the account needs "Replicating Directory Changes" and "Replicating Directory Changes All" at the domain root. Without these rights, syncing will not work.
Note: If you do not use Password Hash Sync, you can take away some replication permissions to lower risk.
Member Server vs Domain Controller
AD Connect is often put on a member server, not a domain controller. This setup brings a special risk. The MSOL_ account can ask for directory data from a server that is not as safe as a domain controller. Attackers like to go after member servers because they are easier to break into.
Member servers do not have as many security controls as domain controllers.
Attackers can break into a member server and use the MSOL_ account to get sensitive data.
The MSOL_ account does not need to log in to a domain controller to copy data.
If an attacker gets the MSOL_ account or the member server, they can use the account’s replication permissions. This lets them copy password hashes and other private information. You might see a Suspected DCSync Attack alert if this happens.
Attack Surface
The MSOL_ account makes your attack surface bigger because of its special rights. Attackers look for accounts with replication permissions. They use tools to pretend to be a domain controller and ask for directory data. This is called a DCSync attack.
When the MSOL_ account has these rights, attackers can:
Copy password hashes for all users, even admins.
Move around your network by using stolen passwords.
Make fake Kerberos tickets and get more access.
Some mistakes can make things worse. The table below shows some errors that increase risk:
Tip: Always check which accounts have replication permissions. Only give these rights to what is needed for AD Connect.
Groups try to keep things safe and working by using least privilege, role-based access, and regular checks. You should watch the MSOL_ account closely and check permissions often. This helps you find real threats and avoid false alarms.
Detecting and Mitigating Attacks
Monitoring Replication Requests
It is important to watch for strange replication activity. This helps you find a Suspected DCSync Attack early. You can use special audit rules to track key events. For example, Event ID 4662 shows when someone touches sensitive directory objects. Event ID 4624 logs when accounts sign in. These events help you see who uses replication rights.
Some tools give real-time alerts and reports. Tools like ManageEngine ADAudit Plus have dashboards that show DCSync attacks and other dangers. These tools use MITRE ATT&CK® rules to help you know when, where, and how each event happens. They also find mistakes in both on-premises and cloud Active Directory.
You should also check network traffic for special requests like DsGetNCChanges. This request is part of the replication process. If you see it from a computer that is not a domain controller, it could be a problem. Compare the source of these requests to your list of domain controllers to spot anything odd.
Tip: Always look at logs for Event ID 4662 with special access rights. This helps you track who uses replication permissions in your system.
Least Privilege Practices
You need to know what least privilege means for MSOL_ accounts. Least privilege means only giving accounts the permissions they need. For MSOL_ accounts, this means only giving the rights needed for AD Connect.
Many groups have problems when they do not use least privilege. For example, using admin accounts as service accounts is risky. Sharing service accounts across many services makes it hard to find problems. It can also cause outages if passwords change. Not changing passwords often or using weak ones also puts your system in danger.
You should always use special service accounts for AD Connect. Do not let these accounts log in directly. Change passwords often and do not set them to never expire. Check which accounts have replication rights and remove any that do not need them.
Note: Using least privilege helps you spot bad actions and limits damage if an account is stolen.
Remediation Steps
You need to know what to do if you find a Suspected DCSync Attack with an MSOL_ account. The best steps are to limit permissions, watch activity, and act fast.
Only let domain controllers and trusted admin accounts have replication rights. Remove extra rights from other accounts.
Check high-privilege groups often. Look for accounts that should not be there or strange replication activity.
Make your monitoring better so you can see odd replication requests right away.
Control which accounts have default replication rights. Only allow Domain Admins, Enterprise Admins, DC computer accounts, and the MSOL_ account for Azure AD Connect.
Check and change permissions for groups like Enterprise Key Admins. Only give full control if needed.
Callout: Regular checks and strong monitoring help you act fast and keep your system safe.
You should also train your admins. Microsoft has training and certifications about identity management, security, and compliance. These programs help your team know what to look for and how to manage MSOL_ accounts safely.
Last, you need to think about compliance. Limit syncing of top-level admin accounts. Use strong authentication and special workstations for privileged access. Regular reviews and plans for incidents help you follow rules and keep your system secure.
You must keep MSOL accounts safe. It is important to know if a Suspected DCSync Attack alert is real or fake. Good security helps protect your directory. Use managed service accounts with passwords that change often. Set up Privileged Access Workstations for important accounts. Turn on Multi-Factor Authentication to make accounts safer.
Check for accounts with replication permissions that should not have them.
Take away extra rights from groups like Administrators and Domain Controllers.
Use tools to spot attackers and confuse them.
Do audits often and update your detection rules.
Tip: Look at all privileged accounts regularly. Change passwords after problems. Turn off accounts until you know they are safe.
FAQ
What is a DCSync attack?
A DCSync attack happens when someone uses special rights to copy password data from Active Directory. Attackers do this to steal password hashes and get more access to your network.
What makes the MSOL_ account a target?
The MSOL_ account has rights to copy data. Attackers want these rights because they let them take important information. You need to watch this account to keep your directory safe.
What should you do if you see a Suspected DCSync alert?
First, check if the alert is from your AD Connect server or the MSOL_ account. If it is, look at your settings. Exclude the server if everything looks normal. Always check to make sure there is no real danger.
What permissions does the MSOL_ account need?
The MSOL_ account needs "Replicating Directory Changes" and "Replicating Directory Changes All" rights. These rights let it sync changes between your local Active Directory and Azure AD.
What steps help reduce false positives for DCSync alerts?
You can add your AD Connect server or MSOL_ account to the exclusions list in your security tool. This helps stop extra false alerts but still lets you watch for real attacks.