PsExec is a powerful command-line utility developed by Sysinternals, a subsidiary of Microsoft. It allows users to execute processes on remote computers without the need for installing any software on the target machine. This tool is widely used by system administrators and IT professionals to manage and troubleshoot remote computers. However, have you ever wondered what happens behind the scenes when you run PsExec on a remote computer? In this article, we will delve into the details of the service that is started on a remote computer when running PsExec on it.
Understanding PsExec
Before we dive into the specifics of the service started by PsExec, let’s take a brief look at how PsExec works. PsExec is a lightweight utility that uses the Windows Remote Management (WinRM) protocol to establish a connection with the remote computer. Once connected, PsExec can execute commands, run programs, and even copy files to and from the remote machine.
PsExec uses the following steps to execute a process on a remote computer:
- The user runs PsExec on their local machine, specifying the remote computer’s name or IP address, along with the command or program to be executed.
- PsExec establishes a connection with the remote computer using the WinRM protocol.
- PsExec copies the executable file to the remote computer’s ADMIN$ share.
- PsExec creates a new service on the remote computer, which is used to execute the copied executable file.
The Service Started by PsExec
So, what service is started on a remote computer when running PsExec on it? The answer lies in the way PsExec uses the Windows Service Control Manager (SCM) to create a new service on the remote machine.
When PsExec connects to a remote computer, it creates a new service called “PSEXESVC” (or “PSEXESVC.exe” on some systems). This service is a temporary service that is used solely for the purpose of executing the command or program specified by the user.
The PSEXESVC service is created in the following location:
C:\Windows\System32\PSEXESVC.exe
This service is started automatically when PsExec connects to the remote computer, and it is stopped and deleted when the PsExec session is terminated.
How PSEXESVC Works
The PSEXESVC service is responsible for executing the command or program specified by the user. Here’s how it works:
- When PsExec creates the PSEXESVC service, it specifies the executable file to be run, along with any command-line arguments.
- The PSEXESVC service starts the executable file, passing any command-line arguments to the program.
- The program runs under the context of the PSEXESVC service, which means it has the same privileges and permissions as the service.
- When the program completes, the PSEXESVC service stops and deletes itself.
Security Implications of PSEXESVC
As with any service that runs on a remote computer, there are security implications to consider when using PsExec and the PSEXESVC service.
Here are a few key points to keep in mind:
- Authentication: PsExec uses the credentials provided by the user to authenticate with the remote computer. If the credentials are not valid, the connection will fail.
- Authorization: The PSEXESVC service runs under the context of the user who started the PsExec session. This means that the service has the same privileges and permissions as the user.
- Encryption: PsExec uses the WinRM protocol to establish a secure connection with the remote computer. This means that all data transmitted between the local and remote machines is encrypted.
Best Practices for Using PsExec and PSEXESVC
To ensure secure and reliable use of PsExec and the PSEXESVC service, follow these best practices:
- Use strong credentials: Always use strong, unique credentials when running PsExec.
- Limit privileges: Ensure that the user account used to run PsExec has only the necessary privileges and permissions to perform the required tasks.
- Monitor activity: Regularly monitor PsExec activity to detect any suspicious or unauthorized access.
Conclusion
In conclusion, when running PsExec on a remote computer, the service started is called PSEXESVC. This temporary service is used to execute the command or program specified by the user and is stopped and deleted when the PsExec session is terminated. By understanding how PsExec and the PSEXESVC service work, system administrators and IT professionals can use these tools more effectively and securely to manage and troubleshoot remote computers.
By following best practices and taking the necessary security precautions, users can ensure that PsExec and the PSEXESVC service are used in a secure and reliable manner.
What is PsExec and how does it work?
PsExec is a command-line utility that allows users to execute processes on remote computers. It is part of the Sysinternals suite of tools developed by Mark Russinovich. PsExec works by establishing a connection to the remote computer using the SMB protocol, which is a standard protocol for sharing files and printers on a network.
When PsExec is run on a remote computer, it creates a temporary service on the remote computer, which is used to execute the specified command or process. This service is created in the context of the local system account, which has elevated privileges on the remote computer. The service is then used to launch the specified process, which runs in the context of the local system account.
What service is started on a remote computer when running PsExec on it?
When PsExec is run on a remote computer, it starts a service called “PsExecsvc” on the remote computer. This service is a temporary service that is created specifically for the purpose of executing the specified command or process on the remote computer.
The PsExecsvc service is created in the context of the local system account, which has elevated privileges on the remote computer. This allows PsExec to execute commands and processes on the remote computer with elevated privileges, even if the user running PsExec does not have administrative privileges on the remote computer.
How does PsExec authenticate with the remote computer?
PsExec authenticates with the remote computer using the credentials provided by the user. When PsExec is run, the user is prompted to enter the username and password of an account that has administrative privileges on the remote computer.
PsExec uses the provided credentials to establish a connection to the remote computer using the SMB protocol. Once the connection is established, PsExec uses the credentials to authenticate with the remote computer and create the PsExecsvc service.
What are the system requirements for running PsExec?
PsExec requires a Windows operating system to run, and it can be used to execute processes on remote computers running Windows XP or later. PsExec also requires the .NET Framework 2.0 or later to be installed on the local computer.
In addition, PsExec requires that the remote computer has the SMB protocol enabled and that the Windows Firewall is configured to allow incoming connections on the SMB port (445). PsExec also requires that the user running PsExec has administrative privileges on the remote computer.
How do I use PsExec to execute a command on a remote computer?
To use PsExec to execute a command on a remote computer, you need to run PsExec from the command line and specify the name of the remote computer, the command to execute, and the credentials to use for authentication.
For example, to execute the command “ipconfig” on a remote computer named “RemotePC”, you would run the following command: “psexec \RemotePC -u Administrator -p Password ipconfig”. This command would execute the “ipconfig” command on the remote computer using the credentials of the Administrator account.
Can I use PsExec to execute a command on multiple remote computers at once?
Yes, PsExec allows you to execute a command on multiple remote computers at once by specifying a list of computer names or IP addresses. You can separate the computer names or IP addresses with commas or use a text file that contains a list of computer names or IP addresses.
For example, to execute the command “ipconfig” on multiple remote computers named “RemotePC1”, “RemotePC2”, and “RemotePC3”, you would run the following command: “psexec \RemotePC1,\RemotePC2,\RemotePC3 -u Administrator -p Password ipconfig”. This command would execute the “ipconfig” command on all three remote computers using the credentials of the Administrator account.
Are there any security risks associated with using PsExec?
Yes, there are security risks associated with using PsExec. PsExec allows you to execute commands and processes on remote computers with elevated privileges, which can be a security risk if not used properly.
In addition, PsExec uses the SMB protocol to establish a connection to the remote computer, which can be vulnerable to man-in-the-middle attacks if not properly secured. It is recommended to use PsExec only on trusted networks and to use secure authentication methods, such as Kerberos or smart cards, to minimize the security risks.