Arthur Pemberton wrote:
On 7/3/07, Mike McCarty <Mike.McCarty@xxxxxxxxxxxxx> wrote:
I already gave instances published by the US Government which
demonstrate that machines which run SELinux are subject to attacks
which would not otherwise have succeeded.
Thanks for brining my attention to that, went back through the thread
and found those links.
As I expected, all those exploits/bugs, require local account access.
Yes, no surprise there.
I don't consider any system in which a local account is attacking the
systems integrity to be very secure, do you? I say that to show that,
I consider that any machine for which access is not physically
assured not to be secure. If there is access which is not physically
secured, as in no external connections, and no one is allowed to
touch the machine physically, then it is not secure. This includes
terminal connections, network connections, modems, etc. Once one
has left total physical security, then one must accept that one
does not have a secure machine, but an insecure one. Then we leave
the realm of security, and enter the realm of relative security.
A machine which is not secure may be relatively secure compared
to another machine. (The other machine may be the same machine,
but running different software. For example, a machine when
booted up under Linux may be relatively secure compared to the
same machine booted under XP. Or with different external
connections, etc.)
Runing SELinux may make a machine relatively more secure in some
senses, and yet make it relatively less secure in other senses.
in such a case, the presence of SELinux cannot be lowering the systems
security that much - the attacker already has local access.
Yes. That's all I meant. That's why I used the qualifier "certain
senses". In other senses, it may make a machine more secure.
Now, SELinux helps to prevent a remote attacker from getting local
access, and (as far as I know) it has no internet facing ports or
other connections.
It may help. It may not. It may help, but only minutely, or even
only theoretically. If no attacker can get past my hardware firewall,
then SELinux cannot improve secrurity, but it may reduce stability
and availability.
So in a case where a machine is being used to host several local
accounts, and local multiuser usage, then I can accept that SELinux
adds vulnerabilities, but I even in that situation, I believe SELinux
adds (security) more than it removes.
Well, now we have entered the arena you before described as FUD.
You believe it is better. Perhaps you are right by your own
criteria. However, at present, there are no universally
accepted criteria by which one may objectively evaluate whether
any additional security added by SELinux exceeds its costs in
reduced security in some areas, reduced availability and/or
reliability, and increased maintenance costs.
At present, this is a subjective matter.
Mike
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