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Sign in. United States English. Ask a question. Quick access. We are trying to make your network so irritating to an attacker that they just lose interest and go after some other target.
The easiest part that you probably already completed. You should be restricting that outbound traffic to only those service IP ranges. We document those here:. DCs and file servers probably need to be accessed from anywhere inside the network, but some application server might just need access from two other application servers on the same subnet.
You enable it as part of group policy and deploy to whatever set of nodes you want to check. Of course! But we can talk tactics. The key thing to understand is blocking both inbound and outbound communications in a very deterministic way using rules that include exceptions and add additional connection security.
Email them a link, convince them to click, and now they are sending along NTLM credentials or running mean executables. An outbound firewall policy that prevents use of SMB connections not just outside the safety of your managed network but even inside your network to only allow access to the minimum set of servers and not any other machines is true lateral movement defense.
This KB covers the precise SMB firewall rules you need to set for inbound and outbound connections to match your inventory. I want to call out a few important points in that KB:. Open Connection Security Rules, create a new Isolation rule. Use the default Requirement "Request authentication for inbound and outbound connections. Set for all profiles, name your rule, and save. Remember that this must be done for all computers - clients and servers - participating in your new inbound and outbound rules or they will be blocked from connecting SMB outbound.
When you provide these secure connection options, you now get access to scopes like authorized computers and IP address:. The defensive impact of this layering means attackers must determine which small set of allowed servers are valid targets that must be controlled or replaced without detection, all within your inner network. Broad lateral movement and client-hopping ransomware will no longer be able to piggyback SMB on end user device.
When I talk about being too irritating of a target, this is what I mean. Far more secure than any firewall is the complete lack of an SMB Server service running at all. Note : I've debated making this service on-demand in the future and perhaps disabled by default in certain conditions and editions like Windows 10 for home users or Professional.
It would initially break a lot of enterprises. Possible scenarios include:. Windows will automatically negotiate this more advanced cipher method when connecting to another computer that supports it, and can also be mandated through Group Policy.
Now data is encrypted before placement, leading to relatively minor performance degradation while adding AES and AES protected packet privacy. This means that when using Storage Spaces Direct and SMB Direct, you can decide to encrypt east-west communications within the cluster itself for higher security. You should note that there is a notable performance operating cost with any end-to-end encryption protection when compared to non-encrypted.
You can enable SMB Encryption for the entire file server or only for specific file shares. Use one of the following procedures to enable SMB Encryption:. This is useful to prevent interception attacks.
This enforces the administrator's intent of safeguarding the data for all clients that access the shares. However, in some circumstances, an administrator may want to allow unencrypted access for clients that do not support SMB 3. To allow unencrypted access for clients that do not support SMB 3. The pre-authentication integrity capability described in the next section prevents an interception attack from downgrading a connection from SMB 3.
However, it does not prevent a downgrade to SMB 1. To guarantee that SMB 3. SMB 3.
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