What is NetExec?
NetExec (formerly CrackMapExec) is a powerful “Swiss Army knife” tool for offensive security engagements, particularly useful for interacting with Active Directory (AD) environments. For someone learning about offensive security, here’s a quick summary of how to use NetExec in an engagement, focusing on SMB enumeration:
NetExec is a command-line tool that automates many tasks in penetration testing, especially against Windows networks. It’s great for authenticating, gathering information, and executing commands over various protocols like SMB, RDP, WinRM, SSH, and LDAP. In an offensive security context, it helps you understand the target network’s weaknesses.
Why SMB Enumeration?
SMB (Server Message Block) is a network file sharing protocol commonly used in Windows environments. Enumerating SMB shares and services can reveal valuable information about a network, including:
- Accessible shares: What files and folders are exposed?
- User and group information: Who has access to what?
- Operating system details: What versions of Windows are running?
- Potential misconfigurations: Are there open shares that shouldn’t be?
This information is crucial for planning further attacks, such as finding sensitive data, identifying weak passwords, or discovering systems to pivot from.
How to Use NetExec for SMB Enumeration (Simplified):
- Installation: NetExec is often pre-installed on Kali Linux. If not, you can usually install it with
sudo apt install netexec. -
Basic Host Discovery (Scanning for SMB):
- To find hosts with SMB enabled on a specific IP range (e.g., 192.168.1.0/24), you’d run:
netexec smb 192.168.1.0/24 - This will list active SMB hosts.
- To find hosts with SMB enabled on a specific IP range (e.g., 192.168.1.0/24), you’d run:
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Enumerating Shares (Anonymous Access):
- Once you’ve identified an SMB host (let’s say 192.168.1.100), you can try to list its shares anonymously:
netexec smb 192.168.1.100 --shares - This attempts to list accessible shares without any credentials. Often, “anonymous” access is disabled, but it’s always worth a try!
- Once you’ve identified an SMB host (let’s say 192.168.1.100), you can try to list its shares anonymously:
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Enumerating Shares (With Credentials):
- In a real engagement, you’ll likely gain credentials at some point. You can use NetExec with a username and password to enumerate shares:
netexec smb 192.168.1.100 -u <username> -p <password> --shares - Replace
<username>and<password>with the actual credentials.
- In a real engagement, you’ll likely gain credentials at some point. You can use NetExec with a username and password to enumerate shares:
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Enumerating Users:
- NetExec can also try to enumerate users on a system via SMB (if allowed):
netexec smb 192.168.1.100 -u <username> -p <password> --user
- NetExec can also try to enumerate users on a system via SMB (if allowed):
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Listing Sessions:
- See who is currently logged into a system:
netexec smb 192.168.1.100 -u <username> -p <password> --sessions
- See who is currently logged into a system:
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Checking for Common Vulnerabilities (e.g., Null Sessions):
- NetExec can automatically check for some common SMB misconfigurations, like null sessions (where unauthenticated users can access information). The basic scan
netexec smb <target>often reveals this.
- NetExec can automatically check for some common SMB misconfigurations, like null sessions (where unauthenticated users can access information). The basic scan
Offensive Security Context:
- Reconnaissance: SMB enumeration is a critical part of the reconnaissance phase. It helps you build a map of the network and identify potential targets.
- Initial Foothold: Finding open shares or weak credentials can be the first step in gaining access to a system.
- Privilege Escalation & Lateral Movement: Information gathered (like user lists or accessible shares) can be used to escalate privileges or move to other machines in the network. For example, if you find a share with sensitive scripts, you might be able to modify them to execute your own code.
- Post-Exploitation: Even after gaining access, NetExec can be used for further enumeration and to maintain persistence.
Key Takeaways for Learners:
- Start Simple: Begin with basic host discovery and anonymous enumeration.
- Understand the Output: Pay attention to what NetExec tells you. Look for “READ,” “WRITE,” or “FULL” access on shares.
- Credentials are Key: Many advanced NetExec features require valid credentials. This highlights the importance of gaining user access during an engagement.
- Ethical Hacking Mindset: Always perform these actions in authorized environments with clear permission.
NetExec is a versatile tool, and the SMB protocol is just one of its many capabilities. As you learn more, you’ll discover its full potential for various stages of an offensive security engagement.