Re: rpcbomb: remote rpcbind denial-of-service

[Marcus Meissner <meissner () suse de>]

On Wed, May 03, 2017 at 05:55:20PM -0700, Seth Arnold wrote:
> On Wed, May 03, 2017 at 08:55:23PM +0200, Guido Vranken wrote:
> > This vulnerability allows an attacker to allocate any amount of bytes
> > (up to 4 gigabytes per attack) on a remote rpcbind host, and the
> > memory is never freed unless the process crashes or the administrator
> > halts or restarts the rpcbind service.
> > [...]
> > An extensive write-up can be found here:
> > https://guidovranken.wordpress.com/2017/05/03/rpcbomb-remote-rpcbind-denial-of-service-patches/
> >
> > Exploit + patches: https://github.com/guidovranken/rpcbomb/
>
> Hello Guido, nice find. Have CVE numbers been requested for this issue
> yet? Have you investigated if ntirpc is affected too? Much of the code
> looks similar:
>
> http://sources.debian.net/src/ntirpc/1.4.3-3/src/rpc_generic.c/#L728

We also saw glibc affected.

https://bugzilla.suse.com/show_bug.cgi?id=1037559#c7

That said, your reproducer allocates virtual memory, and on systems with overcommit
there is only neglible impact on overall memory pressure.

The rpc service will however likely crash at some point though when there is no virtual
address space left for it.

Ciao, Marcus