What are null sessions

Many administrators on college and office networks, for instance, maintain an online guide to common network tasks, including disallowing null sessions. If users do not feel comfortable doing this, they can ask someone in the IT department to configure their computer to address this potential security exploit. Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a EasyTechJunkie researcher and writer.

Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors. Mary McMahon. The first line of the table tells us that the name of the machine running at This line contains the workgroup or the domain the computer is joined to: And this is the most interesting line of the table!

You can also perform shares enumeration from a Linux machine. You need to use the tools provided by the Samba suite. Samba tools are already installed in Kali Linux, but you can install them in nearly every Linux distribution.

To perform the same operations of nbtstat, you can use nmblookup with the same command line switch:. Here are the results we get from running nmblookupon the same target machine. We get the same results:. You even ran the commands to prove it. Now you think Microsoft is up to their old tricks. Fine, let me prove it to you. These are all tests anyone can run to confirm. The second command sets no explicit credentials. This is where the more interesting behavior will happen because it leaves room for Windows to try implicit credentials.

Names Pipes are an old-school method used to allow two services to talk with each other, even over a network connection. Older versions of Windows may behave differently than these tests. This is the basic home scenario. Two computers used by a regular folks who just want things to work without ever opening a settings console in their entire life.

This is all expected behavior because RedWrk and BlueWrk have no inherent trust between each other. No centralized authentication method means that each workgroup member must rely on their local security database, which does not contain details about the other workgroup member s unless those details are explicitly added.

This means that all anonymous and implicit authentication methods will fail. RedWrk and BlueWrk were joined to the domain for the next step. This is where things start to get interesting for us. Remember when I said Windows really wants to make that connection work? Specifically, the Session Setup part, where authentication happens.

This is the same mechanism that allows you to connect to your work shared drives through Windows Explorer without explicitly entering your Windows credentials, just in command line form. Since valid domain credentials were passed and accepted, this is not a null session. Even though it may look like one on the surface. This is because an IP address requires a little extra setup to be a valid Kerberos object. Also, NTLM is in plain text which makes authentication easier to understand in the context of an article.

Same story as the previous command. SMB used the domain account of the logged-on user and the connection was successful. Kerberos is really the way to go. Security Blob: abb2aaa10baf…. Simple Protected Negotiation. This behavior is not necessarily default in older versions of Windows.

Pen tests can only go into so much depth in its analysis. Privacy policy. Sometimes a call arriving on the null session can appear like an authenticated call. Specifically, calling the RpcBindingInqAuthClient function returns the authentication level and security provider used for the call.

This operation does not mean the call was not on a null session.