full-disclosure - Re: ISC DHCP Client [3.0.x to 4.2.x] Arbitrary Command Execution (CVE-2011-0997)

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Date: Thu, 07 Apr 2011 09:20:53 +1200
From: Nick FitzGerald <nick@...us-l.demon.co.uk>
To: full-disclosure <full-disclosure@...ts.grok.org.uk>
Subject: Re: ISC DHCP Client [3.0.x to 4.2.x] Arbitrary
 Command Execution (CVE-2011-0997)

coderman to Valdis.Kletnieks:

> > Otherwise if a valid dhcp server hands you foo.bar.baz.example.com your hostname
> > just became foobarbazexamplecom - whoops.
> 
> a DHCP server should not reply with a FQDN as hostname.
> 
> hostname 'foo' at domainname 'bar.baz.example.com' is legit though...

So Valdis' complaint about the "fix:

   new_host_name=${new_host_name//[^a-zA-Z0-9]/}

still partly stands.

They should at least have gone with:

   new_host_name=${new_host_name//[^-a-zA-Z0-9]/}

as hyphens are valid in host names.

Whether the code should gracefully handle itself in misconfigured 
environments, or more, to what extent it should, is ultimately up to 
the developers, so they can quibble over the dot character...

Regards,

Nick FitzGerald

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