windows.weak.passwds.txt

`Secure Storage of Secrets in Windows  
  
Aleph One ([email protected])  
Mon, 17 May 1999 14:57:31 -0700   
  
Not long ago we discussed why you still see messages that describe  
yet another application that stores passwords in an insecure manner,  
in particular under Windows. The bottom line was that there are two  
common cases.  
  
The first one is where an application needs to authenticate a user  
again the password. In many of these cases the plaintext password  
can be replaced by a one way hash with little or no loss of functionality.  
The second case is that where an application requires the password  
to authenticate itself against a service on behalf of the user but  
without prompting them for the password after the first time.  
  
Several people mentioned that an application or agent could be created  
that can store securely these secrets for many applications. The user  
would then only need to authenticate itself once again this application  
or agent to allow any other applications running under its id to request  
their secrets. Although this system does not stop rouge applications  
(e.g. trojans, BackOrifice) from stealing the secrets, it does stop a whole  
range of vulnerabilities from doing so (e.g. javascript file stealing  
vulnerabilities, world-readable shares, etc).  
  
The Win32 API provides such service. Although in the past it was found  
that its encryption was rather weak Microsoft claims to have fixed it,  
no one else has claimed otherwise, and its better than nothing.  
(References: http://www.netsys.com/firewalls/firewalls-9512/0442.html  
http://www.geek-girl.com/bugtraq/1995_4/0138.html ).  
  
So here is a reminder to Windows application programs that you can use  
WNetCachePassword and WNetGetCachedPassword, which in some documentation  
MS calls the Master Password API.  
  
--  
Aleph One / [email protected]  
http://underground.org/  
KeyID 1024/948FD6B5  
Fingerprint EE C9 E8 AA CB AF 09 61 8C 39 EA 47 A8 6A B8 01  
  
--------------------------------------------------------------------------  
  
Date: Tue, 18 May 1999 12:35:28 +0000  
From: Nick FitzGerald <[email protected]>  
To: [email protected]  
Subject: Re: Secure Storage of Secrets in Windows  
  
> The Win32 API provides such service. Although in the past it was  
> found that its encryption was rather weak Microsoft claims to have  
> fixed it, no one else has claimed otherwise, and its better than  
> nothing. (References:  
> http://www.netsys.com/firewalls/firewalls-9512/0442.html  
> http://www.geek-girl.com/bugtraq/1995_4/0138.html ).  
>  
> So here is a reminder to Windows application programs that you can  
> use WNetCachePassword and WNetGetCachedPassword, which in some  
> documentation MS calls the Master Password API.  
  
Indeed.  
  
And for admins who wish to prevent user machines from caching  
passwords the following Win9x REG file may be useful:  
  
REGEDIT4  
  
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\Network]  
"DisablePwdCaching"=dword:00000001  
  
Apply that to a client machine then nuke all PWL files in the Windows  
dir and you need not worry whether future vulnerabilities might open  
you to exposure from cached passwords.  
  
I imagine there is something similar for NT. Anyone know the  
details?  
  
  
Regards,  
  
Nick FitzGerald  
  
--------------------------------------------------------------------------  
  
Date: Wed, 19 May 1999 09:42:51 +0300  
From: Olaf Titz <[email protected]>  
To: [email protected]  
Subject: Re: Secure Storage of Secrets in Windows  
  
> The Win32 API provides such service. Although in the past it was found  
> that its encryption was rather weak Microsoft claims to have fixed it,  
> no one else has claimed otherwise, and its better than nothing.  
  
Since this allows the encryption of user data and Microsoft ist U.S.  
based , the algorithm _must_ be weak. Otherwise they could have used  
just RC4 with the password as key instead of RC4 with a 32 bit(!)  
hash of the password. This is not Microsoft stupidity but U.S.  
government stupidity.  
  
With today's CPU power 32 bit of key is not better than nothing.  
I could brute force that in one week with my single PC.  
  
Olaf  
  
--------------------------------------------------------------------------  
  
Date: Wed, 19 May 1999 23:21:57 +0200  
From: Eivind Eklund <[email protected]>  
To: [email protected]  
Subject: Re: Secure Storage of Secrets in Windows  
  
On Wed, May 19, 1999 at 09:42:51AM +0300, Olaf Titz wrote:  
> > The Win32 API provides such service. Although in the past it was found  
> > that its encryption was rather weak Microsoft claims to have fixed it,  
> > no one else has claimed otherwise, and its better than nothing.  
>  
> Since this allows the encryption of user data and Microsoft ist U.S.  
> based , the algorithm _must_ be weak. Otherwise they could have used  
> just RC4 with the password as key instead of RC4 with a 32 bit(!)  
> hash of the password. This is not Microsoft stupidity but U.S.  
> government stupidity.  
>  
> With today's CPU power 32 bit of key is not better than nothing.  
> I could brute force that in one week with my single PC.  
  
I'll just note that back when PWL breaking was fairly new, Frank  
Stevenson (mostly) with a tiny bit of help from yours truly optimized  
a breaker for this to run in just under 24 hours on a Pentium 90 (or  
perhaps it was a Pentium 66 - I no longer remember).  
  
The next day Frank found the vulnerabilities that let us crack the  
passwords in no time at all, due to incorrect initialization of RC4,  
but we had it under 24 hours before that :-)  
  
Eivind.  
  
---------------------------------------------------------------------------  
  
Date: Thu, 20 May 1999 19:14:49 +0200  
From: Bronek Kozicki <[email protected]>  
To: [email protected]  
Subject: Re: Secure Storage of Secrets in Windows  
  
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Hash: SHA1  
  
To disable password caching in Windows NT one should set following  
registry value to 0. By default it's not set, and assumed to be 10 .  
  
Hive: HKEY_LOCAL_MACHINE  
Key: Software\Microsoft\Windows NT\CurrentVersion\Winlogon  
Name: CachedLogonsCount  
Type: REG_DWORD  
Value: 0 to 50  
  
Information about this registry value can be found in KB, article  
Q172931.  
  
Bronek Kozicki  
  
- --------------------------------------------------  
ICQ UID: 25404796 PGP KeyID: 0x4A30FA9A  
07EE 10E6 978C 6B33 5208 094E BD61 9067 4A30 FA9A  
  
  
  
- -----Original Message-----  
>From: Bugtraq List [mailto:[email protected]]On Behalf Of Nick  
FitzGerald  
Sent: Tuesday, May 18, 1999 2:35 PM  
To: [email protected]  
Subject: Re: Secure Storage of Secrets in Windows  
  
  
> The Win32 API provides such service. Although in the past it was  
> found that its encryption was rather weak Microsoft claims to have  
> fixed it, no one else has claimed otherwise, and its better than  
> nothing. (References:  
> http://www.netsys.com/firewalls/firewalls-9512/0442.html  
> http://www.geek-girl.com/bugtraq/1995_4/0138.html ).  
>  
> So here is a reminder to Windows application programs that you can  
> use WNetCachePassword and WNetGetCachedPassword, which in some  
> documentation MS calls the Master Password API.  
  
Indeed.  
  
And for admins who wish to prevent user machines from caching  
passwords the following Win9x REG file may be useful:  
  
REGEDIT4  
  
  
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\  
Network]  
"DisablePwdCaching"=dword:00000001  
  
Apply that to a client machine then nuke all PWL files in the Windows  
dir and you need not worry whether future vulnerabilities might open  
you to exposure from cached passwords.  
  
I imagine there is something similar for NT. Anyone know the  
details?  
  
  
Regards,  
  
Nick FitzGerald  
  
  
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