Removal of 1024 bit roots - Thawte and GTE CyberTrust

[Hubert Kario]

I've finally found some time to analyse the data from last months scan
to see what happens when additional roots are removed[1,2].

The scan took place between 11th and 19th of July 2014.
Sites scanned are taken from Alexa top 1 million sites as of 11th of July.

Overall, the certificate stats look like this:

Statistics from 440559 chains provided by 585568 hosts

Server provided chains Count Percent
-------------------------+---------+-------
complete 363296 62.0416
incomplete 29441 5.0278
untrusted 192831 32.9306

Trusted chain statistics
========================

Chain length Count Percent
-------------------------+---------+-------
2 2385 0.5414
3 428839 97.3397
4 9314 2.1141
5 21 0.0048

CA key size in chains Count
-------------------------+---------
ECDSA 256 3
ECDSA 384 3
RSA 1024 1718
RSA 2045 1
RSA 2048 868749
RSA 4096 17615

Chains with CA key Count Percent
-------------------------+---------+-------
ECDSA 256 3 0.0007
ECDSA 384 3 0.0007
RSA 1024 1708 0.3877
RSA 2045 1 0.0002
RSA 2048 438889 99.6209
RSA 4096 17235 3.9121

Signature algorithm (ex. root) Count
------------------------------+---------
ecdsa-with-SHA384 3
sha1WithRSAEncryption 384856
sha256WithRSAEncryption 49903
sha384WithRSAEncryption 12768

Eff. host cert chain LoS Count Percent
-------------------------+---------+-------
80 385704 87.5488
112 54852 12.4505
128 3 0.0007

Removing the Thawte 1024 bit roots[1] causes following changes:

Untrusted: +33 sites.
Incomplete chain: +153, -2 sites.
Complete chain: -184 sites.

Sites that become untrusted:
aclen...@199.242.144.30
brillen...@83.141.56.30
copagloj...@54.225.100.66
cqccms...@124.207.135.23
datatil...@80.232.122.99
drew...@77.75.249.212
easy-fo...@64.14.56.6
fachverlag-com...@78.111.65.215
foreverwe...@208.77.51.191
gold-supe...@94.186.152.196
gold-to...@94.186.152.196
gol...@194.97.154.131
gumball...@134.0.19.106
joker...@89.250.52.17
loyte...@88.198.4.4
madeind...@194.213.124.118
meven...@78.47.246.235
motor-...@94.198.62.121
nct...@193.120.166.32
nct...@193.120.166.32
now...@119.146.222.146
pctonl...@66.181.99.28
recycling...@66.181.99.26
santan...@212.78.166.49
showoffi...@91.216.34.51
slotas...@54.204.19.24
tcd...@134.226.14.90
todayn...@119.146.222.146
whitire...@202.2.11.59
www.cqcc...@125.35.1.213
www.n...@119.146.222.153
www.toda...@119.146.222.153
www.u...@131.128.1.19

Adding certificate from comment 13 from bugzilla[1] changes the stats
compared to above results in very small way, only 6 hosts loose untrusted
status:

aclen...@199.242.144.30
cqccms...@124.207.135.23
easy-fo...@64.14.56.6
madeind...@194.213.124.118
santan...@212.78.166.49
www.cqcc...@125.35.1.213

So in total, removal of certificates referenced in [1] makes at least 27 hosts untrusted.

Removal of the GTE root has bigger impact:

complete -86
incomplete +17, -8
untrusted +77

since the list is so large I won't be quoting it here.

As such, I'd say that removing those roots now would be premature.

1 - https://bugzilla.mozilla.org/show_bug.cgi?id=986014
2 - https://bugzilla.mozilla.org/show_bug.cgi?id=1047011
--
Regards,
Hubert Kario
Quality Engineer, QE BaseOS Security team
Email: hka...@redhat.comg
Web: www.cz.redhat.com
Red Hat Czech s.r.o., Purkyňova 99/71, 612 45, Brno, Czech Republic

[Kathleen Wilson]

On 9/2/14, 10:53 AM, Hubert Kario wrote:
> I've finally found some time to analyse the data from last months scan
> to see what happens when additional roots are removed[1,2].
>
> The scan took place between 11th and 19th of July 2014.
> Sites scanned are taken from Alexa top 1 million sites as of 11th of July.
>

Hubert, Thank you for doing this analysis and sharing your findings.

Looks like those SSL certs are 5 year certs that were issued in 2010, so
those site administrators will be needing to update their certs within
the next year.

The change is currently targeted for Firefox 35 (early January). That
gives Thawte/Symantec time to contact these customers, and get their
certs updated.

> Removal of the GTE root has bigger impact:
>
> complete -86
> incomplete +17, -8
> untrusted +77
>
> since the list is so large I won't be quoting it here.

Would you please attach the list to the bug?

Thanks,
Kathleen

[Hubert Kario]

----- Original Message -----
> From: "Kathleen Wilson" <kwi...@mozilla.com>
> To: mozilla-dev-s...@lists.mozilla.org
> Sent: Tuesday, September 2, 2014 10:43:56 PM
> Subject: Re: Removal of 1024 bit roots - Thawte and GTE CyberTrust
>
> On 9/2/14, 10:53 AM, Hubert Kario wrote:

> Looks like those SSL certs are 5 year certs that were issued in 2010, so
> those site administrators will be needing to update their certs within
> the next year.
>
> The change is currently targeted for Firefox 35 (early January). That
> gives Thawte/Symantec time to contact these customers, and get their
> certs updated.

OK, I'll definitely will do another scan before that time.

> > Removal of the GTE root has bigger impact:
> >
> > complete -86
> > incomplete +17, -8
> > untrusted +77
> >
> > since the list is so large I won't be quoting it here.
>

> Would you please attach the list to the bug?

done

--
Regards,
Hubert Kario
Quality Engineer, QE BaseOS Security team
Email: hka...@redhat.com