r-project.org SSL certificate issues

On Aug 19, 2020, at 13:35, Toby Hocking <tdhock5 at gmail.com> wrote:

Hi win-builder certificate expired on Aug 15. My student on the other side
of the world is also seeing this problem so I think it needs to be fixed...

download.file("https://win-builder.r-project.org", "/tmp/wb.html")

trying URL 'https://win-builder.r-project.org'
Error in download.file("https://win-builder.r-project.org", "/tmp/wb.html")
:
 cannot open URL 'https://win-builder.r-project.org'
In addition: Warning message:
In download.file("https://win-builder.r-project.org", "/tmp/wb.html") :
 URL 'https://win-builder.r-project.org/': status was 'Peer certificate
cannot be authenticated with given CA certificates'

On Wed, Jun 10, 2020 at 2:40 AM G?bor Cs?rdi <csardi.gabor at gmail.com> wrote:

My (also not expert) understanding is that there is nothing insecure about
alternative certificate chains at all. All browsers and macOS's built in
SSL library (secure transport) support them properly. OpenSSL and LibreSSL
were/are simply broken. This was not such a big issue so far, but now that
some old long lived certificates are expiring, it is increasingly an issue.

FWIW it is possible to build libcurl on macOS without any external SSL
library, so OpenSSL and LibreSSL are not needed at all. (Unfortunately the
libcurl build that comes with most (all?) macOS versions does use
LibreSSL.) The R installer could link to such a static libcurl library on
macOS, and that would solve the issue for macOS. Whether it should, that's
another question.

Gabor

On Wed, Jun 10, 2020 at 9:56 AM peter dalgaard <pdalgd at gmail.com> wrote:

As I said, there is stuff that I don't understand in here.... (including
why browsers apparently do trust alternative chains)

-pd

On 10 Jun 2020, at 01:53 , Simon Urbanek <simon.urbanek at R-project.org>

wrote:

You are making a very strong assumption that finding an alternative

chain of trust is safe. I'd argue it's not - it means that an adversary
could manipulate the chain in a way to trust it instead of the declared
chain and thus subverting it. In fact switching to OpenSSL would create a
serious security hole here - in particular since it installs a separate
trust store which it is far more easily attacked and subverted. By your
argument we should disable all SSL checks as that produces error with
incorrectly configured servers so not performing checks is better. It is
true that R is likely not used for sensitive transactions, but I would
rather it warned me about situations where the communication may be
compromised instead of just silently going along.

Cheers,
Simon

On Jun 10, 2020, at 11:39 AM, peter dalgaard <pdalgd at gmail.com>

wrote:

Yes and no... At least as I understand it (Disclaimer: There are

things

I am pretty sure that I don't understand properly, somewhere in the

Bermuda

triangle beween CA bundles, TLS protocols, and Server-side settings),

there

are two sided to this:

One is that various *.r-project.org servers got hit by a fumble where

a higher-up certificate in the chain of trust expired before the *.
r-project.org one. This was fixed by changing the certificate chain on
each server.

The other side is that this situation hit Mac users harder than

others,

because Apple's LibreSSL doesn't have the same feature that openSSL has

to

detect a secondary chain of trust when the primary one expired. This was
not unique to R - svn also failed from the command line - but it did

affect

download.file() inside R.

The upshot is that there might be 3rd party servers with a similar

certificate setup which have not been updated like *.r-project.org. This
is not too unlikely since web browsers do not have trouble accessing

them,

and the whole matter may go undetected. For such servers, download.file()
would still fail.

I.e., there is a case to be made that we might want to link openSSL

rather than LibreSSL.  On the other hand, I gather that newer versions of
LibreSSL contain the relevant protocol upgrade, so maybe one can just

wait

for Apple to update it. Or maybe we do want to link R against openSSL,

but

almost certainly not for a hotfix release.

Best
-pd

On 10 Jun 2020, at 00:50 , Simon Urbanek <simon.urbanek at R-project.org

wrote:

To be clear, this not an issue in the libraries nor R, the

certificates on the server were simply wrong. So, no, this has nothing to
do with R.

Cheers,
Simon

On Jun 10, 2020, at 10:45 AM, Henrik Bengtsson <

henrik.bengtsson at gmail.com> wrote:

Was this resolved upstream or is this something that R should/could
fix? If the latter, could this also go into the "emergency release"

R

4.0.2 that is scheduled for 2020-06-22?

My $.02

/Henrik


On Sun, May 31, 2020 at 8:13 AM G?bor Cs?rdi <

csardi.gabor at gmail.com>

wrote:

Btw. it would be also possible to create a macOS R installer that
embeds a static or dynamic libcurl with Secure Transport, instead

of

the Apple default LibreSSL.

This might be too late for R 4.0.1, I don't know.

Gabor

On Sun, May 31, 2020 at 4:09 PM G?bor Cs?rdi <

csardi.gabor at gmail.com>

wrote:

On Sat, May 30, 2020 at 11:32 PM G?bor Cs?rdi <

csardi.gabor at gmail.com> wrote:

[...]

Btw. why does this affect openssl? That root cert was published

in

2010, surely openssl should know about it? Maybe libcurl /

openssl

only uses the chain provided by the server? Without trying to use

an

alternate chain?

Yes, indeed it seems that old OpenSSL versions cannot handle
alternative certificate chains. This has been fixed in OpenSSL in
2015, so modern Linux systems should be fine. However, macOS uses
LibreSSL, and LibreSSL never fixed this issue. E.g.
https://github.com/libressl-portable/portable/issues/595

r-project.org can be updated to send the new root certificate,

which

will solve most of our problems, but we'll probably have issues

with

other web sites that'll update slower or never.

FWIW I built macOS binaries for the curl package, using a static
libcurl and macOS Secure Transport, so these binaries does not

have

this issue.

They are at https://files.r-hub.io/curl-macos-static and they can

be

installed with
install.packages("curl", repos =
"https://files.r-hub.io/curl-macos-static", type = "binary")

They support R 3.2 and up, including R 4.1, and should work on all
macOS versions that the given R release supports.

Gabor

--
Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Office: A 4.23
Email: pd.mes at cbs.dk  Priv: PDalgd at gmail.com

--
Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Office: A 4.23
Email: pd.mes at cbs.dk  Priv: PDalgd at gmail.com

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