Reading User Cannot Change Password (LDAP Provider)
The ability of a user to change their password is a permission that can be granted or denied.
To determine if the change password permission is granted or denied
Bind to the user object.
Obtain the IADsSecurityDescriptor object from the ntSecurityDescriptor property of the user object.
Obtain an IADsAccessControlList interface for the security descriptor from the IADsSecurityDescriptor.DiscretionaryAcl property.
Enumerate the access control entries (ACE) for the object and search for the ACEs that have the change password GUID ({AB721A53-1E2F-11D0-9819-00AA0040529B}) for the IADsAccessControlEntry.ObjectType property and "Everyone" or "NT AUTHORITY\SELF" well-known security principals for the IADsAccessControlEntry.Trustee property.
Note
The "Everyone" and "NT AUTHORITY\SELF" strings are localized based on the language of the first domain controller in the domain. Therefore, the strings should not be used directly. The account names should be obtained at run time by calling the LookupAccountSid function with the SID for the "Everyone" ("S-1-1-0") and "NT AUTHORITY\SELF" ("S-1-5-10") well-known security principals. The following C++ GetSidAccountName, GetSidAccountName_Everyone, and GetSidAccountName_Self code examples show how to do this.
If both the "Everyone" and "NT AUTHORITY\SELF" ACEs have the ADS_ACETYPE_ACCESS_DENIED_OBJECT value for the IADsAccessControlEntry.AceType property, then the permission is denied.
Example Code
The following code example shows how to determine if the User Cannot Change Password Permission using the LDAP provider.
/***************************************************************************
GetSidAccountName()
Retrieves the account name for the specified SID.
pSid - Pointer to the SID that the account name should be retrieved for.
pbstrAccountName - Pointer to a BSTR that receives the account name. The
caller must free this with SysFreeString when it is no longer required.
***************************************************************************/
HRESULT GetSidAccountName(PSID pSid, BSTR *pbstrAccountName)
{
if(!pbstrAccountName)
{
return E_INVALIDARG;
}
HRESULT hr = E_FAIL;
BOOL fReturn;
WCHAR wszAccountName[MAX_PATH];
DWORD dwAccountName;
WCHAR wszDomainName[MAX_PATH];
DWORD dwDomainName;
SID_NAME_USE SidNameUse;
DWORD dwSidSize;
dwAccountName = MAX_PATH;
dwDomainName = MAX_PATH;
dwSidSize = SECURITY_MAX_SID_SIZE;
/*
Get the account name for the specified SID.
*/
fReturn = LookupAccountSidW(
NULL,
pSid,
wszAccountName,
&dwAccountName,
wszDomainName,
&dwDomainName,
&SidNameUse);
if(fReturn)
{
CComBSTR sbstrReturn;
if(lstrlenW(wszDomainName) > 0)
{
sbstrReturn = wszDomainName;
sbstrReturn += "\\";
sbstrReturn += wszAccountName;
}
else
{
sbstrReturn = wszAccountName;
}
*pbstrAccountName = sbstrReturn.Detach();
hr = S_OK;
}
return hr;
}
/***************************************************************************
GetSidAccountName_Everyone()
Retrieves the local account name for the "World", also known as
"Everyone", account.
pbstrAccountName - Pointer to a BSTR that receives the account name. The
caller must free this with SysFreeString when it is no longer required.
***************************************************************************/
HRESULT GetSidAccountName_Everyone(BSTR *pbstrAccountName)
{
if(!pbstrAccountName)
{
return E_INVALIDARG;
}
HRESULT hr = E_FAIL;
BOOL fReturn;
PSID psidAlloc;
// Create the SID for "Everyone".
SID_IDENTIFIER_AUTHORITY SidAuth = SECURITY_WORLD_SID_AUTHORITY;
fReturn = AllocateAndInitializeSid(
&SidAuth,
1,
SECURITY_WORLD_RID,
0, 0, 0, 0, 0, 0, 0,
&psidAlloc);
if(fReturn)
{
hr = GetSidAccountName(psidAlloc, pbstrAccountName);
LocalFree(psidAlloc);
}
return hr;
}
/***************************************************************************
GetSidAccountName_Self()
Retrieves the local account name for the "NT AUTHORITY\SELF" account.
pbstrAccountName - Pointer to a BSTR that receives the account name. The
caller must free this with SysFreeString when it is no longer required.
***************************************************************************/
HRESULT GetSidAccountName_Self(BSTR *pbstrAccountName)
{
HRESULT hr = E_FAIL;
BOOL fReturn;
PSID psidAlloc;
// Create the SID for "Everyone".
SID_IDENTIFIER_AUTHORITY SidAuth = SECURITY_NT_AUTHORITY;
fReturn = AllocateAndInitializeSid(
&SidAuth,
1,
SECURITY_PRINCIPAL_SELF_RID,
0, 0, 0, 0, 0, 0, 0,
&psidAlloc);
if(fReturn)
{
hr = GetSidAccountName(psidAlloc, pbstrAccountName);
LocalFree(psidAlloc);
}
return hr;
}
#define CHANGE_PASSWORD_GUID_W L"{AB721A53-1E2F-11D0-9819-00AA0040529B}"
/***************************************************************************
GetObjectACE()
Retrieves the IADsAccessControlEntry for the ACE that matches the
specified object type and trustee in the specified IADsAccessControlList.
Returns a value other than S_OK if the ACE is not found.
pACL - Pointer to an IADsAccessControlList object that will be searched.
pwszObject - Pointer to a null-terminated Unicode string that contains
the object type to find.
pwszTrustee - Pointer to a null-terminated Unicode string that contains
the trustee to find.
ppACE - Pointer to an IADsAccessControlEntry pointer that receives the
ACE if successful. This receives NULL if not successful.
***************************************************************************/
HRESULT GetObjectACE(IADsAccessControlList* pACL,
LPCWSTR pwszObject,
LPCWSTR pwszTrustee,
IADsAccessControlEntry** ppACE)
{
if(NULL == pACL || NULL == pwszObject)
{
return E_INVALIDARG;
}
*ppACE = NULL;
HRESULT hr;
IUnknown *pUnk;
hr = pACL->get__NewEnum(&pUnk);
if(FAILED(hr))
{
return hr;
}
IEnumVARIANT *pEnum;
hr = pUnk->QueryInterface(IID_IEnumVARIANT, (LPVOID*)&pEnum);
if(SUCCEEDED(hr))
{
ULONG ulFetched;
BOOL fEveryone = FALSE;
BOOL fSelf = FALSE;
CComVariant svarACE;
for(hr = pEnum->Next(1, &svarACE, &ulFetched);
S_OK == hr && 1 == ulFetched;
hr = pEnum->Next(1, &svarACE, &ulFetched))
{
if(VT_DISPATCH == svarACE.vt)
{
IADsAccessControlEntry *pACE;
hr = svarACE.pdispVal->QueryInterface(IID_IADsAccessControlEntry, (void**)&pACE);
if(SUCCEEDED(hr))
{
CComBSTR sbstrObjectType;
hr = pACE->get_ObjectType(&sbstrObjectType);
if(SUCCEEDED(hr))
{
if(0 == lstrcmpiW(pwszObject, sbstrObjectType))
{
CComBSTR sbstrTrustee;
hr = pACE->get_Trustee(&sbstrTrustee);
if(SUCCEEDED(hr) && (0 == lstrcmpiW(sbstrTrustee, pwszTrustee)))
{
*ppACE = pACE;
break;
}
}
}
pACE->Release();
}
}
}
pEnum->Release();
}
return hr;
}
/***************************************************************************
UserCannotChangePassword()
Retrieves the "User Cannot Change Password" privilege using the LDAP
provider. This is determined by the presence and value of the change
password GUID ACE for the Everyone and Self trustees. The default result
of this function is that the user can change their password unless the
two ACEs specifically deny the privilege.
pwszUserDN - A null-terminated Unicode string that contains the LDAP
ADsPath of the user object to verify.
pwszUsername - A null-terminated Unicode string that contains the user
name to use for authorization. If this is NULL, the credentials of the
current user are used.
pwszPassword - A null-terminated Unicode string that contains the
password to use for authorization. This is ignored if pwszUsername is
NULL.
pfCannotChangePassword - Receives the setting for the privilege.
Receives nonzero if the user cannot change their password or zero if
the can change their password.
***************************************************************************/
HRESULT UserCannotChangePassword(LPCWSTR pwszUserDN,
LPCWSTR pwszUsername,
LPCWSTR pwszPassword,
BOOL *pfCannotChangePassword)
{
HRESULT hr;
CComBSTR sbstrEveryone;
hr = GetSidAccountName_Everyone(&sbstrEveryone);
if(FAILED(hr))
{
return hr;
}
CComBSTR sbstrSelf;
hr = GetSidAccountName_Self(&sbstrSelf);
if(FAILED(hr))
{
return hr;
}
if(NULL == pwszUserDN)
{
return E_INVALIDARG;
}
IADs *pads;
*pfCannotChangePassword = FALSE;
hr = ADsOpenObject( pwszUserDN,
pwszUsername,
pwszPassword,
ADS_SECURE_AUTHENTICATION,
IID_IADs,
(LPVOID*)&pads);
if(SUCCEEDED(hr))
{
CComVariant svar;
hr = pads->Get(CComBSTR("ntSecurityDescriptor"), &svar);
if(SUCCEEDED(hr))
{
IADsSecurityDescriptor *psd;
hr = svar.pdispVal->QueryInterface(IID_IADsSecurityDescriptor, (LPVOID*)&psd);
if(SUCCEEDED(hr))
{
IDispatch *pDisp;
hr = psd->get_DiscretionaryAcl(&pDisp);
if(SUCCEEDED(hr))
{
IADsAccessControlList *pACL;
hr = pDisp->QueryInterface(IID_IADsAccessControlList, (void**)&pACL);
if(SUCCEEDED(hr))
{
BOOL fEveryone = FALSE;
BOOL fSelf = FALSE;
IADsAccessControlEntry *pACEEveryone = NULL;
IADsAccessControlEntry *pACESelf = NULL;
// Get the ACE for everyone.
hr = GetObjectACE(pACL, CHANGE_PASSWORD_GUID_W, sbstrEveryone, &pACEEveryone);
// Get the ACE for self.
hr = GetObjectACE(pACL, CHANGE_PASSWORD_GUID_W, sbstrSelf, &pACESelf);
if(pACEEveryone && pACESelf)
{
LONG lAceType;
hr = pACEEveryone->get_AceType(&lAceType);
if(SUCCEEDED(hr) && (ADS_ACETYPE_ACCESS_DENIED_OBJECT == lAceType))
{
fEveryone = TRUE;
}
hr = pACESelf->get_AceType(&lAceType);
if(SUCCEEDED(hr) && (ADS_ACETYPE_ACCESS_DENIED_OBJECT == lAceType))
{
fSelf = TRUE;
}
}
if(fEveryone && fSelf)
{
*pfCannotChangePassword = TRUE;
}
else
{
*pfCannotChangePassword = FALSE;
}
}
pDisp->Release();
}
psd->Release();
}
}
pads->Release();
}
return hr;
}
The following code example shows how to determine the User Cannot Change Password Permission using the LDAP provider.
Note
The following code example only works for domains where the primary language is English, because the "Everyone" and "NT AUTHORITY\SELF" strings are localized based on the language of the first domain controller in the domain. There is no way in Visual Basic to obtain the account names for a well-known security principal without calling the LookupAccountSid function. If using Visual Basic, it is suggested that you use the WinNT provider to determine the User Cannot Change Password Permission as shown in Reading User Cannot Change Password (WinNT Provider).
Const CHANGE_PASSWORD_GUID = "{AB721A53-1E2F-11D0-9819-00AA0040529B}"
Const ADS_ACETYPE_ACCESS_DENIED_OBJECT = &H6
Function UserCannotChangePassword(strUserDN As String, strUsername As String, strPassword As String) As Boolean
UserCannotChangePassword = False
Dim oUser As IADs
Dim oSecDesc As IADsSecurityDescriptor
Dim oACL As IADsAccessControlList
Dim oACE As IADsAccessControlEntry
Dim fEveryone As Boolean
Dim fSelf As Boolean
fEveryone = False
fSelf = False
If "" <> strUsername Then
Dim dso As IADsOpenDSObject
' Bind to the group with the specified user name and password.
Set dso = GetObject("LDAP:")
Set oUser = dso.OpenDSObject(strUserDN, strUsername, strPassword, 1)
Else
' Bind to the group with the current credentials.
Set oUser = GetObject(strUserDN)
End If
Set oSecDesc = oUser.Get("ntSecurityDescriptor")
Set oACL = oSecDesc.DiscretionaryAcl
For Each oACE In oACL
If UCase(oACE.ObjectType) = UCase(CHANGE_PASSWORD_GUID) Then
If oACE.Trustee = "Everyone" And oACE.AceType = ADS_ACETYPE_ACCESS_DENIED_OBJECT Then
fEveryone = True
End If
If oACE.Trustee = "NT AUTHORITY\SELF" And oACE.AceType = ADS_ACETYPE_ACCESS_DENIED_OBJECT Then
fSelf = True
End If
End If
Next
If fSelf And fEveryone Then
UserCannotChangePassword = True
Else
UserCannotChangePassword = False
End If
End Function
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