Re: Sensationalism? [was Re: FW: Man in the middle attack against RFC3456.]

["Scott Fanning" <sfanning@cisco.com>]

In actuality, most service providers use RADIUS as a server to get ip
address, so how does DHCP fit in that (+ many other service provider
specific attributes)? Do we have to now translate between DHCP and RADIUS?
DHCP is not the only way to get addresses, but mode config allows the
security GW to be flexible on how ip addresses are acquired.

I also vote against the special SA. Having to create an SA, then to find out
that the ip address pool is exhausted, seems like alot of state to deal
with.

As for inside attacks, maybe you should talk to "security" experts who seem
to indicate that 59% of attacks are from the inside of the network.

"In the 2002 CPI/FBI survey, for instance, 59 percent of organizations
surveyed admitted to at least one internal attack."

Yeah, the RADIUS server is vulnerable too, but at least you don't waste QM
mode.

Anyway, my two cents. I am sure you will shoot it down. This is a good
debate. Too bad it was not this vigorous during the standardization process.
Oh yes, it was, but it was out of scope, out of charter.

Scott
----- Original Message -----
From: "Scott G. Kelly" <scott@bstormnetworks.com>
To: <ddukes@cisco.com>
Cc: <ipsec@lists.tislabs.com>
Sent: Wednesday, February 05, 2003 11:51 AM
Subject: Sensationalism? [was Re: FW: Man in the middle attack against
RFC3456.]


> Come on, Darren - you must be joking. What you describe is not an attack
> against RFC3456 - it's an attack against DHCP/BOOTP, and this is nothing
> new. If you run DHCP on your network and you have malicious insiders,
> they can do all sorts of things. The same applies for most other
> commonly run lan protocols. And since you've already conceded that a
> scalable modecfg implementation will be running dhcp on the backend,
> what is the point of this post?
>
> Let's stick with arguments with technical merit.
>
> Scott
>
> Darren Dukes wrote:
> >
> > Amendment:
> > Eve sends the DHCPACK to the DHCP-relay (not the IRAC) with a
manufactured
> > DHCP Relay Agent Information Option or one copied from a previous DHCP
> > message.
> >
> > > -----Original Message-----
> > > From: Darren Dukes [mailto:ddukes@cisco.com]
> > > Sent: Wednesday, February 05, 2003 12:10 PM
> > > To: ipsec@lists.tislabs.com
> > > Subject: Man in the middle attack against RFC3456.
> > >
> > >
> > > There is a man in the middle attack on the DHCP-relay in RFC3456.
> > > This attack is based on the thread defined in RFC3118
> > > (DHCP-AUTH).  In this case Eve is inside the LAN and able to
> > > source DHCPACK packets, if Eve sends a DHCPACK to a an IRAC via a
> > > SGW implementing RFC3456 the DHCP-relay on the SGW will plumb a
> > > new route for whatever address Eve puts in yiaddr.
> > >
> > >                |-Eve
> > > IRAC ---- SGW -|
> > >                |-DHCP Server
> > >
> > > excerpt from RFC3456:
> > >    To learn the internal IP address of the client in order to route
> > >    packets to it, the security gateway will typically snoop the yiaddr
> > >    field within the DHCPACK and plumb a corresponding route as part of
> > >    DHCP Relay processing.
> > >
> > > This attack is not resolved by the implementation of RFC3118
> > > unless the following changes are made to the DHCP-relay.
> > > 1 - It stored a copy of all secret keys contained on the
> > > DHCP-server and used them to authenticate DHCPACKs or it stored a
> > > copy of the master key and used that to generate the client keys
> > > as described in RFC3118 Appendix A.
> > > 2 - DHCP-relay implements the DHCP-server replay protection.
> > >
> > >
> > > Darren
> > >
>