Re: Problem with IIS5 - "expired" CRLs not working?

From: David Cross [MS] (dcross_at_online.microsoft.com)
Date: 03/29/04


Date: Mon, 29 Mar 2004 05:53:47 -0800

I need to know if your certs actually contain a CDP extension or not. based
on my previous reply, this may be the problem and difference between win2k
and 2003.

-- 
David B. Cross [MS]
--
This posting is provided "AS IS" with no warranties, and confers no rights.
http://support.microsoft.com
"Ohaya" <ohaya@cox.net> wrote in message news:40672ECA.40A8B8A5@cox.net...
> Hi,
>
> Since the last post below, I've been continuing to try all manner of
> things to try to get Windows 2000 AS to actually "care" about the
> validity period of the CRL in the ICA, but unfortunately, have failed.
>
> It appears that Win2K AS simply doesn't check the validity period of the
> CRL.
>
> I have tried setting a number of the Metabase parameters, and was
> especially hopeful with CertCheckMode, because the descriptions on MS'
> website and that SSLDiag displays actually SAY that under certain
> settings (e.g., CertCheckMode=2), revocation checking will FAIL if the
> CRL is expired.
>
> But, this has all been for nought.  Nada.  Nothing.
>
> Sorry to be so verbal, but this is getting frustrating!!
>
> FYI, I've revisited our operational procedures.  Originally, the way the
> procedures were written, they were mainly geared towards insuring and
> verifying that our CRL retrievals were occurring successfully.  This was
> because the assumption was that IIS would actually obey the CRL validity
> period.
>
> But, if IIS does NOT obey the CRL validity period, then I fear that our
> procedures will need to be extended to not only verifying that our CRL
> retrieval process was successful, but we'll also have to actually check
> each CRL to make sure that the CRLs are not stale.  This is because if
> we cannot depend on IIS to check the CRL validity period, and if one of
> our CAs just happens not to update their CRL, even if we successfully
> retrieve the CRL, we could end up with a stale CRL, and IIS would just
> continue to merrily allow connections from clients.
>
> So, I'd really like to request that anyone from Microsoft who is
> monitoring these newsgroups to please review this problem/issue and to
> please respond so that I can determine what I need to do.
>
> Jim
>
>
>
> Ohaya wrote:
> >
> > David,
> >
> > Prior to doing the clean Win2K3 installation, I had imaged the clean
> > Win2K AS installation so that I could relatively easily switch back and
> > forth between Win2K AS and Win2K3.
> >
> > I've been doing further testing, and, at this point, I can confirm that
> > on Win2K Advanced Server (SP4), the validity period of CRLs is being
> > ignored.  More specifically, what I have been able to test is that even
> > when the "Next Update" date on CRLs has passed, IIS5 is still processing
> > connection requests normally.
> >
> > I would guess that this is probably a problem with CryptoAPI, i.e., it's
> > not just IIS5 users that would be affected.
> >
> > Assuming that my testing thus far holds, is there some mechanism for
> > letting Microsoft aware of this?
> >
> > As I mentioned earlier, under normal operational procedures, this
> > problem hopefully won't be a problem, but, if for some reason, there
> > happens to be a situation where a CRL doesn't get updated on a timely
> > basis, this then becomes a real security vulnerability IMHO.
> >
> > Jim
> >
> > Ohaya wrote:
> > >
> > > Hi,
> > >
> > > I just got done installing Windows 2003 (took me 3 tries :(), and
IIS6,
> > > and in this clean, "out-of-the-box" configuration, I tested, and,
> > > indeed, it appears that:
> > >
> > > 1) Win2K3 *DOES* obey the validity period in the CRLs (whereas Windows
> > > 2000 AS apparently does not).
> > >
> > > 2) Win2K3 *DOES* lock down the website if NO CRL is in the ICA store
> > > (again my client certs don't have CDP populated).
> > >
> > > As with the earlier clean-install Win2K AS, this Win2K3 install was as
a
> > > standalone server (no AD and no Certificate Services).
> > >
> > > Re. #2 above, I need to add that initially, obviously, there was not a
> > > CRL stored in the ICA, and in this initial configuration, IIS6 did
allow
> > > connections.
> > >
> > > I then did testing using CertMgr to add a CRL (to test the validity
> > > period checking), and after that, I deleted the CRL from the ICA.
> > >
> > > After I deleted the CRL from the ICA, IIS6 would not allow
connections.
> > >
> > > Jim
> > >
> > > Ohaya wrote:
> > > >
> > > > David,
> > > >
> > > > Thank goodness you're still here!!
> > > >
> > > > I'll check on CAPIMON and with the registry thing you pointed to,
but FYI,
> > > > I'm starting to come to the conclusion that this (and another
problem) are
> > > > Win2K AS-related (vs. Win2K3).  Let me try to explain...
> > > >
> > > > Late last year, when I first started testing, I started with a
Win2K3
> > > > installation.  During that time, I began keeping a project notebook,
where I
> > > > commented on my test results (including a lot of the conversations I
had
> > > > here and on the inetserver.iis.security NG).  According to my notes
at that
> > > > time, I confirmed that Win2K3/IIS6 did a couple of things (that were
good,
> > > > security-wise):
> > > >
> > > > - It obeyed the CRL validity period (Next Update date, etc.), and
> > > > - If no CRL was in the ICA store (deleted from store using
CertMgr.exe and
> > > > confirmed using the MMC Certificates snap-in), IIS6 would not allow
> > > > connections at all for the website.
> > > >
> > > > As I continued testing, I eventually got a Win2K AS CD from my
company,
> > > > since what we were actually going to stand up were Win2K AS
machines.
> > > >
> > > > From my notes from that time, it appears that I did not go back and
check
> > > > those 2 behaviors that I mentioned above related to CRL processing.
> > > >
> > > > I really should have noticed at least the first problem, a LONG time
ago,
> > > > since the Next Update date on the test CRLs that I got was January
29, 2004,
> > > > but very stupidly on my part, I didn't :(...
> > > >
> > > > In other words, we're using these same test CRLs in a couple of
different
> > > > test labs (all running Win2K Server or Advanced Server), and they're
ALL
> > > > still working, and I didn't even think about it.  Darn!!!
> > > >
> > > > Just recently, I started putting together a "Lessons Learned"
document for
> > > > my company, and actually for our partner community, and in beginning
to do
> > > > that, I started going back through my notes and trying to reproduce
the
> > > > results that I had documented in my notes.
> > > >
> > > > And, that's when I started finding these differences/problems.
> > > >
> > > > I am going to have to try to recreate my earlier Win2K3 environment,
but
> > > > I've already created a clean install of Win2K AS (SP4), and with the
Win2K
> > > > AS, it is definitely working with the expired CRLs, and IIS5
definitely is
> > > > not shutting down websites that are SSL (client) secured when I
delete the
> > > > CRL from the ICA store.
> > > >
> > > > Once I get some time to rebuild a Win2K3 environment, I'll try this
again,
> > > > but unless my (voluminous) notes are completely whacked, I think
that I'm
> > > > going to find that Win2K3 does obey the CRL expiration date and does
lock
> > > > down the SSL (client) secured websites when I delete the CRL from
the ICA
> > > > store.
> > > >
> > > > Our policy and standard maintenance practices do call for ensuring
that the
> > > > CRLs are both populated and updated, so hopefully this won't be a
problem,
> > > > but if things turn out the way I'm alluding to above, these 2
problems seem
> > > > like a kind of major problem in Win2K AS/IIS5?
> > > >
> > > > Will post back, but probably not immediately...
> > > >
> > > > Jim
> > > >
> > > > "David Cross [MS]" <dcross@online.microsoft.com> wrote in message
> > > > news:u18e3pAFEHA.3096@TK2MSFTNGP11.phx.gbl...
> > > > > As an additional troubleshooting step, you can use CAPIMON to
debug
> > > > exactly
> > > > > what IIS is doing and what information is being returned by
CryptoAPI
> > > > > through CAPIMON:
> > > > >
> > > > >
> > > >
http://www.microsoft.com/downloads/details.aspx?FamilyId=0BFE87A8-4E79-4441-9D4C-0CAB35D49A01&displaylang=en.
> > > > >
> > > > > --
> > > > >
> > > > >
> > > > > David B. Cross [MS]
> > > > >
> > > > > --
> > > > > This posting is provided "AS IS" with no warranties, and confers
no
> > > > rights.
> > > > >
> > > > > http://support.microsoft.com
> > > > >
> > > > > "Ohaya" <ohaya@N_O_S_P_A_M_cox.net> wrote in message
> > > > > news:4064E434.1B258495@N_O_S_P_A_M_cox.net...
> > > > > > Hi,
> > > > > >
> > > > > > I have a new/clean Win2K Advanced Server installation with IIS5.
This
> > > > > > machine is a standalone server, i.e., it is not a member of a
domain,
> > > > > > and I've updated Win2K through SP4.
> > > > > >
> > > > > > The IIS5 website is configured for SSL with client and server
> > > > > > authentication, and that part is working.  My server and client
certs
> > > > > > are issued by a 3rd party CA, and all the client certs do not
have the
> > > > > > CDP populated.
> > > > > >
> > > > > > For my testing earlier, my CA provided me with several test
CRLs, along
> > > > > > with associated client certs, and I've been using CertMgr.exe to
import
> > > > > > the test CRLs into the Intermediate Certification Authorities
(ICA)
> > > > > > store during my testing.
> > > > > >
> > > > > >
> > > > > > However, today I noticed that the test CRLs all have a "Next
Update"
> > > > > > date of 1/29/04, and since today is 3/26/04, I can't understand
how
> > > > > > these CRLs could still be working.  It seems like they should be
> > > > > > considered invalid and that since IIS5 is calling CryptoAPI to
do the
> > > > > > CRL checking, that I should be getting some kind of error?
> > > > > >
> > > > > > I've checked the system date on the server, and it's definitely
correct
> > > > > > (today's date), so I'm really puzzled.  I really have the
impression
> > > > > > that CryptoAPI (and thus IIS5) would throw some kind of error if
the CRL
> > > > > > was not within the validity period.
> > > > > >
> > > > > > Can someone explain why these out-of-validity-period CRLs still
seem to
> > > > > > work all right?
> > > > > >
> > > > > > Thanks,
> > > > > > Jim
> > > > >
> > > > >


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