SMB (Server Message Block) Protocol Basics

SMB in a CLI world

If you are new or like me forget the bazzilion command syntaxes in the world, the use of the man command will be super helpful as well as google foo! To help people on their way here are some example of basic SMB tools, these come with kali.

SMB Ports

SMB typically operated on TCP 445

Nmap Example

CTF

Server Message Block (SMB) Enumeration, Attack and Defence

Introduction

If you see a service with TCP port 445 open, then it is probably running SMB. SMB is used for file sharing services. You will also see it related to other protocols in its operation:

https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-smb2/06451bf2-578a-4b9d-94c0-8ce531bf14c4

Checklist

Here is a check list of common things to check:

Can you enumerate the server version?
Can you enumerate shares?
What versions of the protocol are enabled?
Can you connect using anon bind?
Are there any known vulnerabilities?
Can you enumerate usernames?
Is SMB signing enabled?
Are there other hosts in the subnet that can be used?