On Thu, 21 Aug 2003, Chris Ricker wrote:
On Thu, 21 Aug 2003, Pekka Savola wrote:
and then join the OpenSSL / OpenSSH exploit train.... No, thanks!
I'm puzzled by this point. These would be local vulnerabilities. There will always be those, and it can be mitigated by keeping the system up-to-date.
Not so. They're remote exploits from anywhere which can connect to OpenSSH.
You really can't "connect to OpenSSH" before hosts.allow kicks in.
If you haven't heard, hosts.allow activates the access controls very, very early in the process. You really can't exploit OpenSSH using that: 1) no SSH protocol processing happens before that, and 2) no input is received or processed before that.
a) tcp wrappers is circumventable. How easily depends on how it's configured....
Users can always misconfigure their systems. Having IP addresses there is pretty bulletproof, and DNS is also OK.
b) you're still attackable from any place you list in hosts.allow, even if tcp wrappers isn't being bypassed. firewalls can be attacked from inside as well as from out....
Only a fool would allow every internal IP to connect to the firewall. You add your firewall manager workstations or network management hosts there and be done with it. If someone breaks into those first, then you're in pretty deep shit anyway.