Re: Re: Busybox on musl is affected by CVE-2015-1817

[Рысь <lynx@sibserver.ru>]

On Thu, 2 Apr 2015 20:36:27 +0200
u-wsnj@aetey.se wrote:

> On Fri, Apr 03, 2015 at 12:26:56AM +0700, Рысь wrote:
> > Audit your filesystem and remove all
> > setuid bits from all programs, move/rename them as prog.real and
> > place a shell script in place which will call setuid wrapper which
> > then will setreuid(uid, 0) then execve().
> 
> This way you are still exposed to setuid and also still depend on how
> the prog.real is going to use the supplied credentials. You more or
> less have to reimplement in your wrapper the checks expected "to be
> already present" in the program, without any control over its
> internals.

If talking about ping issue then yes, ping and other such programs must
not even start to process user input when not sure. You've got setuid
-- quickly drop it when needed privileged resource is obtained. Tools
just need to be fixed, without surrounding scream and initiating
another security dances which usually only hurt.

Instead of wrapper there maybe limiting group which members can run
program, but Unix credentials were always somewhat limited and at some
point you understand that without certain things like ACLs or sudo you
can't effectively partition privileges.

> 
> This can certainly improve the situation if you are (which presumably
> is the case) more security-oriented and thoughtful than the upstream
> developer, but you are in an uphill battle.
> 
> For me this does not look like a solution, rather like a patchwork
> which may or may not be effective.
> 
> Rune
>