mailing list archives
Re: [Full-disclosure] Microsoft DNS resolver: deliberately sabotaged hosts-file lookup
From: Joachim Schipper <j.schipper () math uu nl>
Date: Fri, 14 Apr 2006 02:13:21 +0200
On Thu, Apr 13, 2006 at 06:29:15PM +0100, Dave Korn wrote:
Hey, guess what I just found out: Microsoft have deliberately sabotaged
their DNS client's hosts table lookup functionality.
(...) I'd try to block (Windows Media Player) it in my hosts file.
Microsoft DNS client special-cases 'go.microsoft.com' and refuses to look
it up in the hosts file.
I'm running fully up-to-date Windows XP SP2. I don't have any pfw
software that could conceivably be interfering, and the windows firewall is
running with more-or-less the default settings (I've only added a couple of
exceptions, no other changes). I don't think this is a false positive.
On reading through %WINDIR%\system32\dnsapi.dll with 'strings', I find the
following hostnames listed. I assume they are all also singled out for
[ I've verified that the same behaviour occurs for office.microsoft.com,
exactly as for go.microsoft.com, but haven't tried any of the others yet.
I'd bet real money on it, though. ]
What's your point? It's not like it's the first piece of software ever
to bypass the hosts file, is it? And if you're a software giant, that's
easy to do at a lower level.
Blacklisting IP addresses by /etc/hosts or equivalent is an extremely
broken way of blocking, anyway; and vague hacks like that need not be
supported. Use a real, non-host-based firewall.
Of course, you might wish to stop certain software from phoning home.
Fine, but use something that works - MS is evil in many ways, but not
because this particular hack happens not to work.
Switching to OSS quite nicely solves all these problems, though.