Full Disclosure mailing list archives

Re: Expired certificate


From: bk <chort0 () gmail com>
Date: Fri, 16 Jul 2010 14:16:33 -0700

So basically you advocate making unplanned changes whenever someone feels like it?

The only problem here is that they let the cert expire.  Being responsible about conducting maintenance, instead of 
having a knee-jerk reaction, isn't to be faulted.

If you think you can write better secure file transfer software, no one is stopping you.  You'll make a fortune.  Just 
remember it has to support more than half a dozen different protocols, support dozens of nodes talking to the same 
storage backends, synchronize data across datacenters, support triggered actions at multiple places in the transaction 
across multiple protocols, support multiple payload encryption protocols, allow single-sign-on authentication with 
third-party vendors, etc, etc, etc.  Oh yeah, it all has to pass independent code-review by external auditors.  At that 
rate, supporting instant application of new certs in a multi-tiered environment with bi-directional trust is a 
cake-walk in comparison.

Simple, right?

I'm done educating you.  I know the software and I know what I'm talking about; clearly you know neither.

On Jul 16, 2010, at 12:49 PM, Junk Meat wrote:

chort or whatever your name is, some of us know what we're doing and don't need to wait 2 weeks for a lousy ssl cert 
update much less a daemon restart... give me a break.

Quit defending the State of California, if they were so up on security they shouldn't have passed SB1386 or any other 
legislation for that matter.  Certificate authorities notify their customers well in advance of expiring certs, 
multiple times in fact, there's no excuse for that and then expecting your clients to violate best practice 
afterward.  As far as change control and system complexity, wise organizations keep things simple not overly complex.

Shawn Dermenjian

On 7/16/2010 3:11 PM, bk wrote:
Maybe you should know what you're talking about before you speculate.  Most daemons require a restart when you 
change their cert.  When you're talking about a service that has guaranteed up-time, it can only be taken down for 
scheduled maintenance.  Changing production systems on a whim totally fails the 'A' in 'CIA' (and possibly the 'I' 
too).  Wise organizations implement change-control policies to keep their critical systems from being run-amok by 
ad-hoc changes.

I'm familiar with the software State of California is using for a lot of their secure file transfers and changing 
the certificate is not as simple as you think (although the software is extremely secure).  There are several 
cross-certification trust relationships that need to be established for the software to continue working after 
replacing certs.

The risk of connecting to a machine with an expired cert is that the cert may have been revoked.  That's why there 
are expiration dates on certs.  Even if you're using a CRL, you cannot have the CRL contain every cert that was 
revoked for all of eternity.  The CRL only contains certs from when they were revoked until when they expire.  That 
keeps CRLs slightly manageable (although OCSP is a much better solution).

If you're still connecting to the same IP and getting the same cert (check the serial number and/or fingerprint), 
then at least you're sending data to where you always have in the past.  What you want to be weary of is if the 
serial number and/or fingerprint change and the cert is still invalid (those will probably both change when the cert 
is re-issued, but then the cert chain and not-before/not-after dates should be legit).

--
chort

On Jul 16, 2010, at 11:31 AM, Junk Meat wrote:

  
Your right Dan, encryption still does take place.  However, its hard to
understand why renewing
a certificate would take so long.  It should take no longer then 1/2
hour to receive a renewed
ssl cert from a certificate authority in my opinion and maybe a few
minutes to push it out depending
on the device that is publishing the cert.

You should tell them that your security policy prevents you from making
a secure ftp transfer to a third
party with an expired certificate that contains non-public information
and see how fast they renew
their certificate.

Basically you are now taking responsibility for any breach in the slight
chance that anything does
happen (man-in-the-middle, or otherwise) because you now know about the
problem.  Have them
acknowledge the expired ssl certificate on their end and sign-off on any
potential litigation that may
result if a breach does happen to occur.

-Shawn Dermenjian


On 7/16/2010 1:10 PM, Daniel Sichel wrote:
    
OK, I am in the Golden state (California) where things are not so golden
at the moment.
I deal with a state agency and use their "secure" ftp site.
Their certificate has expired and won't be renewed for a few weeks, but
they want me to continue to ftp stuff
Using their expired cert.

So, as a relative n00b,  what are the risks?

Does it still encrypt even though, obviously, it can't be verified?

My guess is that this still encrypts, but there is no authentication,
possibly creating a man in the middle opportunity for some
Nefarious person with evil intent (nobody I know, or who is on this
list, of course).


Anyway, any info would be welcome from the cognoscenti who subscribe
here.

Thanks,
Dan Sichel

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