Friday, November 8, 2002

Policies for the passwords caching management in Internet Explorer

mad hack

The article gives the System Policies, which manage the caching, on the other hand, saving to the local drive, the passwords in Internet Explorer.

The dialog box will appear, requesting additional credentials whether to save or not password, after the password is entered to the form window in Internet Explorer. Later, the password will not to be entered once more time, when the same page with the same input form is opened. That is the very password caching.

On the one hand, the password caching is the obvious facility for user, who may even forget the entered password, on other hand, is the serious security threat, because the unhampered access to password-protected resource is possible, it is enough for this to know its exact name. If in Windows the automatic completion for the addresses or forms in Windows or Internet Explorer is enabled, so called AutoComplete, the task is simplified to minimum. The very feature of automatic completion gives out the item list, while exploring which it is possible to guess the exact name of resource. The one taken item given by automatic completion can be deleted from the list. The item must be selected and the DEL must be clicked afterwards. However, this feature does not for the drop-down addresses list entered in Internet Explorer address box.

If one opens in browser "Internet Options (Properties)" the page with "Content" tab, one can see the "AutoComplete" button. On clicking this button, the dialog box appears containing the check boxes for the control over "Use AutoComplete for": "Web addresses", "Forms", "User names and passwords on forms" and "Prompt me to save passwords". The password caching in Web pages forms can be totally disabled with check box named "User names and passwords on forms". The check box "Prompt me to save passwords" deselecting disables all the further caching, but, the passwords, entered before, are still automatically suggested, when the user name is entered in the same form. The passwords AutoComplete prohibition in settings does not clean the information on names and passwords corresponding to them, which is already entered before, which; there are to buttons for this to "Clear AutoComplete history", which are located below, in the same dialog box, named: "Clear Forms", "Clear Passwords".

The full consideration of the AutoComplete feature is out of this article topic. I note two facts in conclusion. The AutoComplete settings, stored addresses, are common either for Internet or Windows Explorer. The last fact: the AutoComplete is nice tool to implement the activity analysis and to reconstruct the user's work.

To avoid unnecessary reiteration and potential discrepancies, caused by the difference inherent to various browsers versions, presence the installed services packs, various Windows versions, I must at once notice, that all the given information was tested on Windows ME, Internet Explorer 5.5, with installed service pack for 128-bit cipher strength.

Disable Password Caching

Here the talk will be about how to disable the password caching in Internet Explorer. This system policy has restricted application. The information given here concerns: the Internet Explorer of 4.01 version with the 2nd service pack installed, the Internet Explorer of 5 and 5.01 versions, working on Windows 95, 98, NT 4.0 and the Internet Explorer 5.01 for Windows 98 Second Edition. For instance, the Internet Explorer of 5.5 version ignored this policy, while performing the test on Windows ME.

The state of this system policy is stored in the numeric "DisablePasswordCaching" value, which must be in "Software\Microsoft\Windows\CurrentVersion\Internet Settings" system registry key, in HKEY_CURRENT_USER hive. Correspondingly, the policy range spreads over the Current User only, but not over all the system. The "1" value enables the policy, the "0" value or its missing disables the policy. "By default" this policy is in disabled state in Internet Explorer and there is password caching in Internet Explorer.

The Microsoft company releases the article Q229940 in MSDN titled: "How to Disable Internet Explorer Password Caching".

Do not allow AutoComplete to save passwords

This system policy has the similar purpose to the previous one. While in active state this system policy disables the automatic completion of the names and passwords in Web-pages forms and prevents from appearance the dialog boxes requesting whether to save or new password. If this policy is enabled, the check boxes "User names and passwords on forms" and "Prompt me to save passwords" become dimmed, showing that blocked both these features and the very possibility to switch them on.

One must select the page with "Content" tab in "Internet Options (Properties)" settings, and later click the "AutoComplete" button in order to see these check boxes.

The value "FormSuggest Passwords", storing this policy, is located in "Software\Policies\Microsoft\Internet Explorer\Control Panel", in HKEY_CURRENT_USER hive. The range of this policy covers only the Current User, registered in the system, but not all the system on the whole. It is not necessary to reboot all the system but will be enough to reload the very browser, closed before this all its instances, to take this policy into effect, when its state is changed.

It is demonstrative, that the Microsoft realisation of this policy provokes more than perplexity. The "FormSuggest Passwords" value can be either of numeric (DWORD) or binary or string type. The missing of value in the system registry brings the policy to the disabled state - state "by default". If the value is of numeric type, the two Boolean values: "1", gives the active state, and "0", which gives disabled, respectively, stands for the representation of two states. When the value is of binary type, it can have two possible values: "01 00 00 00" for active state and "00 00 00 00" for not active.

The strangest reaction of this policy was on the content of this value of string type. The empty string or the "yes", "no", "1" and "0"content bring the policy to active state. The strings "true" and "false" or total missing of value cancel its effect. The symbol case had no effect.

The active state of the policy for "prohibition for AutoComplete to save passwords" does not lead to erasing the information that is already entered into history journal, which stores the names and corresponding to them passwords.

And last note: the "FormSuggest Passwords" value, storing in "Software\Policies\Microsoft\Internet Explorer\Control Panel" key and the value with the same name, which can be stored in "Software\Microsoft\Internet Explorer\Main" key, possibly appearing in either HKEY_LOCAL_MACHINE, or HKEY_CURRENT_USER hives are not to be mixed. The last value belongs to the browser setting, storing the state of check box with name "User names and passwords on forms".

The implementation in Activity and Authentication Analyzer

In order to see the state of above-mention policy "Disable Password Caching" or to manipulate it in Activity and Authentication Analyzer follow in the left navigation pane next way:

Computer Administration then Internet Explorer and find it in the right list item corresponding to this policies named:

  • Disable Password Caching

In order to see the state of above-mention policy "Do not allow AutoComplete to save passwords" or to manipulate it in Activity and Authentication Analyzer follow in the left navigation pane next way:

Computer Administration then Internet Explorer, then IE Tools and find it in the right list item corresponding to this policies named:

  • Do not allow AutoComplete to save passwords

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