OT: Rapid Reset attacks on HTTP/2

[Jeffrey Walton]

Hi Everyone,

This just made my radar:
.

From the article:

F5, in an independent advisory of its own, said the attack impacts the
NGINX HTTP/2 module and has urged its customers to update their NGINX
configuration to limit the number of concurrent streams to a default of
128 and persist HTTP connections for up to 1000 requests.

Jeff
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Re: OT: Rapid Reset attacks on HTTP/2

[Jérémy Lal]

Hi,

from the article, these are the default values, so not too much to worry
yet.

Le mar. 10 oct. 2023 à 20:51, Jeffrey Walton  a écrit :

> Hi Everyone,
>
> This just made my radar:
> .
>
> From the article:
>
> F5, in an independent advisory of its own, said the attack impacts the
> NGINX HTTP/2 module and has urged its customers to update their NGINX
> configuration to limit the number of concurrent streams to a default of
> 128 and persist HTTP connections for up to 1000 requests.
>
> Jeff
> ___
> nginx mailing list
> nginx@nginx.org
> https://mailman.nginx.org/mailman/listinfo/nginx
>
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Re: OT: Rapid Reset attacks on HTTP/2

[Maxim Dounin]

Hello!

On Tue, Oct 10, 2023 at 02:50:37PM -0400, Jeffrey Walton wrote:

> Hi Everyone,
> 
> This just made my radar:
> .
> 
> From the article:
> 
> F5, in an independent advisory of its own, said the attack impacts the
> NGINX HTTP/2 module and has urged its customers to update their NGINX
> configuration to limit the number of concurrent streams to a default of
> 128 and persist HTTP connections for up to 1000 requests.

The "the attack impacts the NGINX HTTP/2 module" claim is 
incorrect, see here:

https://mailman.nginx.org/pipermail/nginx-devel/2023-October/S36Q5HBXR7CAIMPLLPRSSSYR4PCMWILK.html

Hope this helps.

-- 
Maxim Dounin
http://mdounin.ru/
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Re: OT: Rapid Reset attacks on HTTP/2

[Jeffrey Walton]

On Tue, Oct 10, 2023 at 3:04 PM Maxim Dounin  wrote:
>
> On Tue, Oct 10, 2023 at 02:50:37PM -0400, Jeffrey Walton wrote:
>
> > This just made my radar:
> > .
> >
> > From the article:
> >
> > F5, in an independent advisory of its own, said the attack impacts the
> > NGINX HTTP/2 module and has urged its customers to update their NGINX
> > configuration to limit the number of concurrent streams to a default of
> > 128 and persist HTTP connections for up to 1000 requests.
>
> The "the attack impacts the NGINX HTTP/2 module" claim is
> incorrect, see here:
>
> https://mailman.nginx.org/pipermail/nginx-devel/2023-October/S36Q5HBXR7CAIMPLLPRSSSYR4PCMWILK.html
>
> Hope this helps.

Thanks Maxim.

The Nginx team may want to publish a blog post or knowledge article. I
got 0 hits when searching the site
. It
will help admins and executives find the team's information.

Jeff
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Re: OT: Rapid Reset attacks on HTTP/2

[Rick Gutierrez]

In the open version 1.24 and 1.25 the correction will be applied?, ¿or in
the new release?

Regards


On Tue, Oct 10, 2023 at 3:46 PM Jeffrey Walton  wrote:

> On Tue, Oct 10, 2023 at 3:04 PM Maxim Dounin  wrote:
> >
> > On Tue, Oct 10, 2023 at 02:50:37PM -0400, Jeffrey Walton wrote:
> >
> > >
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Re: OT: Rapid Reset attacks on HTTP/2

[Maxim Dounin]

Hello!

On Tue, Oct 10, 2023 at 05:30:52PM -0400, Rick Gutierrez wrote:

> In the open version 1.24 and 1.25 the correction will be applied?, ¿or in
> the new release?

To re-iterate:

We do not consider nginx to be affected by this issue.  In the 
default configuration, nginx is sufficiently protected by the 
limit of allowed requests per connection (see 
http://nginx.org/r/keepalive_requests for details), so an attacker 
will be required to reconnect very often, making the attack 
obvious and easy to stop at the network level.  And it is not 
possible to circumvent the max concurrent streams limit in nginx, 
as nginx only allows additional streams when previous streams are 
completely closed.

Further, additional protection can be implemented in nginx by 
using the "limit_req" directive, which limits the rate of requests 
and rejects excessive requests.

Overall, with the handling as implemented in nginx, impact of 
streams being reset does no seem to be significantly different 
from impacts from over workloads with large number of requests 
being sent by the client, such as handling of multiple HTTP/2 
requests or HTTP/1.x pipelined requests.

Nevertheless, we've decided to implemented some additional 
mitigations which will help nginx to detect such attacks and drop 
connections with misbehaving clients faster.  The patch to do so 
was committed (http://hg.nginx.org/nginx/rev/cdda286c0f1b) and 
will be available in the next nginx release.

-- 
Maxim Dounin
http://mdounin.ru/
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