[Openstack-security] [Bug 1274034] Re: Neutron firewall anti-spoofing does not prevent ARP poisoning

Jeremy Stanley fungi at yuggoth.org
Fri May 15 13:28:29 UTC 2015


It _may_ be a security issue in your environment if you haven't
mitigated it through other means already. That Neutron didn't do if for
you in earlier releases doesn't mean it's a vulnerability in Neutron
however, just that it was not a problem Neutron's anti-spoofing rules
were originally designed to solve (much in the same way that a you
wouldn't consider a helmet flawed just because it fails to protect your
knees).

As previously discussed Neutron developers and the OpenStack
Vulnerability Management Team have chosen not to consider a lack of Nova
Network feature parity in Neutron a security vulnerability, just an
incomplete design which could stand to be improved.

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https://bugs.launchpad.net/bugs/1274034

Title:
  Neutron firewall anti-spoofing does not prevent ARP poisoning

Status in OpenStack Neutron (virtual network service):
  In Progress
Status in OpenStack Security Advisories:
  Invalid
Status in OpenStack Security Notes:
  Fix Released

Bug description:
  The neutron firewall driver 'iptabes_firawall' does not prevent ARP cache poisoning.
  When anti-spoofing rules are handled by Nova, a list of rules was added through the libvirt network filter feature:
  - no-mac-spoofing
  - no-ip-spoofing
  - no-arp-spoofing
  - nova-no-nd-reflection
  - allow-dhcp-server

  Actually, the neutron firewall driver 'iptabes_firawall' handles only
  MAC and IP anti-spoofing rules.

  This is a security vulnerability, especially on shared networks.

  Reproduce an ARP cache poisoning and man in the middle:
  - Create a private network/subnet 10.0.0.0/24
  - Start 2 VM attached to that private network (VM1: IP 10.0.0.3, VM2: 10.0.0.4)
  - Log on VM1 and install ettercap [1]
  - Launch command: 'ettercap -T -w dump -M ARP /10.0.0.4/ // output:'
  - Log on too on VM2 (with VNC/spice console) and ping google.fr => ping is ok
  - Go back on VM1, and see the VM2's ping to google.fr going to the VM1 instead to be send directly to the network gateway and forwarded by the VM1 to the gw. The ICMP capture looks something like that [2]
  - Go back to VM2 and check the ARP table => the MAC address associated to the GW is the MAC address of VM1

  [1] http://ettercap.github.io/ettercap/
  [2] http://paste.openstack.org/show/62112/

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