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Re: [SECURITY] [DSA 3481-1] glibc security update



On Wed, 2016-02-17 at 10:55 +0000, Dominic Hargreaves wrote:
> "Mitigating factors for UDP include [...]
>     - A local resolver (that drops non-compliant responses)."
> 
> "- A back of the envelope analysis shows that it should be possible
> to
>   write correctly formed DNS responses with attacker controlled
> payloads
>   that will penetrate a DNS cache hierarchy and therefore allow
>   attackers to exploit machines behind such caches."
> 
> These two statements seem at odds with each other. Does anyone have
> any additional observations on this point?
I tried finding an answer to the same question, and stumbled across an
article from the SANS Internet Storm Center [1], which seems to support
statement one:

"What can you do?
[...]
- make sure all systems on your network use a specific resolver and
block outbound DNS unless it originates from this resolver (this is a
good idea anyway!). This will limit exposure to the resolver"

But having additional confirmation on this matter would be very much
appreciated.

Cheers,
Tom.

[1] https://isc.sans.edu/forums/diary/CVE20157547+Critical+Vulnerabilit
y+in+glibc+getaddrinfo/20737/

-- 
Thomas "Duke" Hager                               duke@sigsegv.at
GPG: 2048R/791C5EB1            http://www.sigsegv.at/gpg/duke.gpg
=================================================================
"Never Underestimate the Power of Stupid People in Large Groups."

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