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OpenSSL Key Recovery Attack on DH small subgroups (CVE-2016-0701)

intothesymmetry.blogspot.com

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Re: OpenSSL Key Recovery Attack on DH small subgroups (CVE-2016-0701)

#11

Post by blakesterz »

jvehent wrote: post #7
asanso wrote: post #5

Earlier quoted context omitted.

indeed. but there is always Static DH :) even if not so popular...

Ops teams need a clear "should I do emergency patching? yes/no" message when any vulnerability gets published. In this instance, it looks like this doesn't require emergency patching unless you're using something unusual to terminate SSL. That said, it's a serious issue, no doubt about that.

I struggle with this sometimes too! So often I read the report and I'm left wondering if I should panic or not, so I start reading comments here and elsewhere to figure out if I need to get this patched OMG RIGHT NOW or I can hold off until the weekend.

I would LOVE a clear "should I do emergency patching? yes/no" it seems like it would be frequently (maybe not always?) something that could be added to an announcement.

Re: OpenSSL Key Recovery Attack on DH small subgroups (CVE-2016-0701)

#12

Post by jvehent »

blakesterz wrote: post #11
jvehent wrote: post #7

Earlier quoted context omitted.

Ops teams need a clear "should I do emergency patching? yes/no" message when any vulnerability gets published. In this instance, it looks like this doesn't require emergency patching unless you're using something unusual to terminate SSL. That said, it's a serious issue, no doubt about that.

I struggle with this sometimes too! So often I read the report and I'm left wondering if I should panic or not, so I start reading comments here and elsewhere to figure out if I need to get this patched OMG RIGHT NOW or I can hold off until the weekend. I would LOVE a clear "should I do emergency patching? yes/no" it seems like it would be frequently (maybe not always?) something that could be added to an announcemen…

That's what your local security team should be for ;) At Mozilla, we track those and inform the various ops teams of our assessments. They very much rely on us to decide if it warrants emergency patching or not (modulo operational concerns to upgrade systems outside maintenance windows).

Re: OpenSSL Key Recovery Attack on DH small subgroups (CVE-2016-0701)

#13

Post by kingkilr »

DannyBee wrote: post #9
kingkilr wrote: post #6

Super happy that the OpenSSL team decided to be proactive and just enable `SSL_OP_SINGLE_DH_USE` for all users, as well as bump the minimum DH key size. Better defaults for everyone!

Yeah, and it looks like BoringSSL did that about a year ago :) https://boringssl.googlesource.com/boringssl/+/9f226a5f5183e...

David's the best :-)

Re: OpenSSL Key Recovery Attack on DH small subgroups (CVE-2016-0701)

#14

Post by detaro »

jvehent wrote: post #12
blakesterz wrote: post #11

Earlier quoted context omitted.

I struggle with this sometimes too! So often I read the report and I'm left wondering if I should panic or not, so I start reading comments here and elsewhere to figure out if I need to get this patched OMG RIGHT NOW or I can hold off until the weekend. I would LOVE a clear "should I do emergency patching? yes/no" it seems like it would be frequently (maybe not always?) something that could be added to an announcemen…

That's what your local security team should be for ;) At Mozilla, we track those and inform the various ops teams of our assessments. They very much rely on us to decide if it warrants emergency patching or not (modulo operational concerns to upgrade systems outside maintenance windows).

Not so great an option if the closest thing to a "local security team" is the sysadmin asking the question ;)

Re: OpenSSL Key Recovery Attack on DH small subgroups (CVE-2016-0701)

#15

Post by sarciszewski »

jvehent wrote: post #7
asanso wrote: post #5

Earlier quoted context omitted.

indeed. but there is always Static DH :) even if not so popular...

Ops teams need a clear "should I do emergency patching? yes/no" message when any vulnerability gets published. In this instance, it looks like this doesn't require emergency patching unless you're using something unusual to terminate SSL. That said, it's a serious issue, no doubt about that.

This is a good point. I'll be sure to put that at the top of any vulnerabilities I report in the future.

Re: OpenSSL Key Recovery Attack on DH small subgroups (CVE-2016-0701)

#16

Post by tokenizerrr »

jvehent wrote: post #12
blakesterz wrote: post #11

Earlier quoted context omitted.

I struggle with this sometimes too! So often I read the report and I'm left wondering if I should panic or not, so I start reading comments here and elsewhere to figure out if I need to get this patched OMG RIGHT NOW or I can hold off until the weekend. I would LOVE a clear "should I do emergency patching? yes/no" it seems like it would be frequently (maybe not always?) something that could be added to an announcemen…

That's what your local security team should be for ;) At Mozilla, we track those and inform the various ops teams of our assessments. They very much rely on us to decide if it warrants emergency patching or not (modulo operational concerns to upgrade systems outside maintenance windows).

That's great. Now what about smaller companies which have one, maybe two sysadmins?

Re: OpenSSL Key Recovery Attack on DH small subgroups (CVE-2016-0701)

#17

Post by dang »

asanso wrote: post #2

hi the author of the vuln here. this is my write up http://intothesymmetry.blogspot.ch/2016/01/openssl-key-recov...

Ok, let's change the URL to that from https://mta.openssl.org/pipermail/openssl-announce/2016-Janu.... An author's writeup counts as the original source, and people always like to find out how it was done.

Re: OpenSSL Key Recovery Attack on DH small subgroups (CVE-2016-0701)

#19

Post by hannob »

kingkilr wrote: post #6

Super happy that the OpenSSL team decided to be proactive and just enable `SSL_OP_SINGLE_DH_USE` for all users, as well as bump the minimum DH key size. Better defaults for everyone!

Interesting that the corresponding ECDH option is still disabled by default and ephemeral keys are cached.

Re: OpenSSL Key Recovery Attack on DH small subgroups (CVE-2016-0701)

#20

Post by kroeckx »

jvehent wrote: post #7
asanso wrote: post #5

Earlier quoted context omitted.

indeed. but there is always Static DH :) even if not so popular...

Ops teams need a clear "should I do emergency patching? yes/no" message when any vulnerability gets published. In this instance, it looks like this doesn't require emergency patching unless you're using something unusual to terminate SSL. That said, it's a serious issue, no doubt about that.

I tried to be clear in when you're vulnerable and when not, so that you can decide if you're vulnerable or not. The answer in this case is "it depends, very likely not".
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