Security Descriptor

 

 

#include <iostream>

#pragma comment(lib, "advapi32.lib")

#include <windows.h>
#include <stdio.h>
#include <aclapi.h>
#include <tchar.h>

bool IsAdmin()
{
    //
    // check if token is member of the Administrators group
    //

    SID_IDENTIFIER_AUTHORITY NtAuthority = SECURITY_NT_AUTHORITY;
    PSID AdministratorsGroup;
    BOOL b = AllocateAndInitializeSid(
        &NtAuthority,
        2,
        SECURITY_BUILTIN_DOMAIN_RID,
        DOMAIN_ALIAS_RID_ADMINS,
        0, 0, 0, 0, 0, 0,
        &AdministratorsGroup);
    if (b) {

        if (!CheckTokenMembership(NULL, AdministratorsGroup, &b))
            b = FALSE;

        FreeSid(AdministratorsGroup);
    }

    return b ? true : false;
}

void main()
{
    std::cout << "IsAdmin:" << IsAdmin() << "\n";

    DWORD dwRes, dwDisposition;
    PSID pEveryoneSID = NULL, pAdminSID = NULL;
    PACL pACL = NULL;
    PSECURITY_DESCRIPTOR pSD = NULL;
    EXPLICIT_ACCESS ea[2];
    SID_IDENTIFIER_AUTHORITY SIDAuthWorld =
        SECURITY_WORLD_SID_AUTHORITY;
    SID_IDENTIFIER_AUTHORITY SIDAuthNT = SECURITY_NT_AUTHORITY;
    SECURITY_ATTRIBUTES sa;
    LONG lRes;
    HKEY hkSub = NULL;
    WCHAR cls[MAX_PATH] = _T("");


    // Create a well-known SID for the Everyone group.
    if (!AllocateAndInitializeSid(&SIDAuthWorld, 1,
        SECURITY_WORLD_RID,
        0, 0, 0, 0, 0, 0, 0,
        &pEveryoneSID))
    {
        _tprintf(_T("AllocateAndInitializeSid Error %u\n"), GetLastError());
        goto Cleanup;
    }

    // Initialize an EXPLICIT_ACCESS structure for an ACE.
    // The ACE will allow Everyone read access to the key.
    ZeroMemory(&ea, 2 * sizeof(EXPLICIT_ACCESS));
    ea[0].grfAccessPermissions = KEY_READ;
    ea[0].grfAccessMode = SET_ACCESS;
    ea[0].grfInheritance = NO_INHERITANCE;
    ea[0].Trustee.TrusteeForm = TRUSTEE_IS_SID;
    ea[0].Trustee.TrusteeType = TRUSTEE_IS_WELL_KNOWN_GROUP;
    ea[0].Trustee.ptstrName = (LPTSTR)pEveryoneSID;

    // Create a SID for the BUILTIN\Administrators group.
    if (!AllocateAndInitializeSid(&SIDAuthNT, 2,
        SECURITY_BUILTIN_DOMAIN_RID,
        DOMAIN_ALIAS_RID_ADMINS,
        0, 0, 0, 0, 0, 0,
        &pAdminSID))
    {
        _tprintf(_T("AllocateAndInitializeSid Error %u\n"), GetLastError());
        goto Cleanup;
    }

    // Initialize an EXPLICIT_ACCESS structure for an ACE.
    // The ACE will allow the Administrators group full access to
    // the key.
    ea[1].grfAccessPermissions = KEY_ALL_ACCESS;
    ea[1].grfAccessMode = SET_ACCESS;
    ea[1].grfInheritance = NO_INHERITANCE;
    ea[1].Trustee.TrusteeForm = TRUSTEE_IS_SID;
    ea[1].Trustee.TrusteeType = TRUSTEE_IS_GROUP;
    ea[1].Trustee.ptstrName = (LPTSTR)pAdminSID;

    // Create a new ACL that contains the new ACEs.
    dwRes = SetEntriesInAcl(2, ea, NULL, &pACL);
    if (ERROR_SUCCESS != dwRes)
    {
        _tprintf(_T("SetEntriesInAcl Error %u\n"), GetLastError());
        goto Cleanup;
    }

    // Initialize a security descriptor.  
    pSD = (PSECURITY_DESCRIPTOR)LocalAlloc(LPTR,
        SECURITY_DESCRIPTOR_MIN_LENGTH);
    if (NULL == pSD)
    {
        _tprintf(_T("LocalAlloc Error %u\n"), GetLastError());
        goto Cleanup;
    }

    if (!InitializeSecurityDescriptor(pSD,
        SECURITY_DESCRIPTOR_REVISION))
    {
        _tprintf(_T("InitializeSecurityDescriptor Error %u\n"),
            GetLastError());
        goto Cleanup;
    }

    // Add the ACL to the security descriptor. 
    if (!SetSecurityDescriptorDacl(pSD,
        TRUE,     // bDaclPresent flag   
        pACL,
        FALSE))   // not a default DACL 
    {
        _tprintf(_T("SetSecurityDescriptorDacl Error %u\n"),
            GetLastError());
        goto Cleanup;
    }

    // Initialize a security attributes structure.
    sa.nLength = sizeof(SECURITY_ATTRIBUTES);
    sa.lpSecurityDescriptor = pSD;
    sa.bInheritHandle = FALSE;


    // Use the security attributes to set the security descriptor 
    // when you create a key.
    lRes = RegCreateKeyEx(HKEY_CURRENT_USER, _T("mykey"), 0, cls, 0,
        KEY_READ | KEY_WRITE, &sa, &hkSub, &dwDisposition);
    _tprintf(_T("RegCreateKeyEx result %u\n"), lRes);

Cleanup:

    if (pEveryoneSID)
        FreeSid(pEveryoneSID);
    if (pAdminSID)
        FreeSid(pAdminSID);
    if (pACL)
        LocalFree(pACL);
    if (pSD)
        LocalFree(pSD);
    if (hkSub)
        RegCloseKey(hkSub);

    return;

}