IPv6 SecurityScott Hogg

Global Technology Resources, Inc.

Director of Technology Solutions

CCIE #5133, CISSP #4610

IPv6 Security – Latent Threat

• Even if you haven’t started using IPv6 yet, you probably have some IPv6 running on your networks already and didn’t know it.

• Do you use Linux, Mac OS X, BSD, or Microsoft Windows 7/8/Win2K8/Win2012 systems in your environment?

• They all come with IPv6 capability enabled by default and prefer IPv6 connectivity

• They may try to use IPv6 first and then fall-back to IPv4 (+|- Happy Eyeballs, RFC 6555)

• Or they may create IPv6-in-IPv4 tunnels to Internet resources to reach IPv6 content

• Some of these techniques take place regardless of user input or configuration

• If you are not protecting your IPv6 nodes then you have just allowed a huge back-door to exist

IPv6 Security Tools

• THC IPv6 Attack Toolkit

• SI6 Networks IPv6 Toolkit

• Evil FOCA

• Metasploit

• Nmap

• halfscan6, Scan6, CHScanner

• Scapy, SendIP, ISIC6, Packit, Spak6

• 6tunneldos, 4to6ddos, imps6-tools

Reconnaissance

• Ping sweeps, port scans, application vulnerability scans are problematic given the large IPv6 address space.

• Brute-force scanning even a single /64 is not practical.

• There are methods of speeding up reconnaissance on LAN.• ping6 -I eth0 ff02::1

• [root@hat ~]# ./alive6 eth0 ff02::1

• Node Information Queries (RFC 4620) in BSD

• Scanning for specific EUI-64 addresses using specific OUIs

• Scanning IPv4 and getting IPv6 info

• Metasploit Framework “ipv6_neighbor" auxiliary module can leverage IPv4 to find IPv6 hosts

• Scanning 6to4, ISATAP, Teredo with embedded IPv4 addresses

• Find one node and leverage the neighbor cache to find other nodes

• DHCPv6 logs, DNS servers, server logs, NMSs, Google Hacking

LAN Threats

• IPv6 uses ICMPv6 for many LAN operations

• Stateless auto-configuration (SLAAC)

• Neighbor Discovery Protocol (NDP)

• IPv6 equivalent of IPv4 ARP – same attack types

• Spoofed RAs can renumber hosts or launch a MITM attack

• Forged NA/NS messages to confuse NDP

• Redirects – same as ICMPv4 redirects

• Forcing nodes to believe all addresses are on-link

• These attacks presume the attacker is on-net or has compromised a local computer (Big Requirement!)

IPv6 MITM Example

• Evil FOCA is a weaponized Win .EXE that can perform dual-protocol MITM and DOS attacks and DNS Hijacking (Released at DEFCON21)

• Sends ICMPv6 RA on LAN (SLAAC)

• Activates IPv6 on local dual-protocol nodes

• Evil FOCA becomes active default gateway

• Sends ICMPv6 NA to spoof local nodes

• Sets up rogue DHCPv6 server

• Performs WPAD attack and sets up proxy

• Performs DNS Hijack

• Can perform RA flood resulting in DOS

Internet

Download at: http://www.informatica64.com/evilfoca/download.aspx

Demo on YouTube: http://www.youtube.com/watch?v=syLoQ4CNfSc

Evil FOCA IPv6 MITM Attack

Evil FOCA IPv6 RA DOSC:\Users\Me>ipconfig

Windows IP Configuration

Ethernet adapter Local Area Connection:

Connection-specific DNS Suffix . :

IPv6 Address. . . . . . . . . . . : 15c2:8297:e614:f45:bc4a:58b9:e948:33c6

. . . (100 of these in Windows 7)

IPv6 Address. . . . . . . . . . . : fcae:a581:9bcb:e6bc:bc4a:58b9:e948:33c6

Temporary IPv6 Address. . . . . . : 15c2:8297:e614:f1f:1ce1:d49d:2ec8:e924

. . . (100 of these in Windows 7)

Temporary IPv6 Address. . . . . . : fcae:a581:9bcb:e6bc:1ce1:d49d:2ec8:e924

Link-local IPv6 Address . . . . . : fe80::bc4a:58b9:e948:33c6%10

IPv4 Address. . . . . . . . . . . : 192.168.11.10

Subnet Mask . . . . . . . . . . . : 255.255.255.0

Default Gateway . . . . . . . . . : fe80::7888:860e:5352:5fec%10

fe80::8d99:1bc3:6f7a:5cf9%10

. . . fe80::a0cf:f7ad:821b:3343%10

192.168.11.1

C:\Users\Me>

THC IPv6 Attack Toolkit

• THC IPv6 Attack Toolkit contains fake_router6• Generates rogue RA to become default router

• Option –H adds a hop-by-hop header• fake_router6 –H eth0 2001:db8:11:11::/64

• Option –F adds a one-shot-fragmentation header• fake_router6 –F eth0 2001:db8:11:11::/64

• Flood_router26 floods RAs to create DOS• flood_router26 eth0

• fake_router26 -E H -A 2001:db8:1:1::/64 eth0

• fake_router26 -E 1 -A 2001:db8:1:1::/64 eth0

Download at: http://thc.org/download.php?t=r&f=thc-ipv6-2.3.tar.gz

Methods of Preventing Rogue RAs

• Prevent unauthorized LAN access (armed guards, malware defenses)

• Disable unused switch ports

• Network Access Control (NAC), Network Admission Control (NAC)

• IEEE 802.1AE (MACsec), Cisco TrustSec

• IEEE 802.1X

• RA Guard (RFC 6105)

• NDPMon

• Ramond

• Kame rafixd

• ipv6mon

• 6Guard

• addrwatch

• Port Security

• Cisco Port-based ACL (PACL)

Allow

Incoming

RA Message

Block

Incoming

RA Message

Allow

Sending

RAs

IPv6 First Hop Security

• Cisco C3750X switch running IOS version 15.2(1)S

ipv6 nd cache interface-limit 3 log 15

ipv6 nd raguard policy HOST

!

ipv6 snooping logging packet drop

ipv6 snooping logging resolution-veto

ipv6 snooping policy ND

limit address-count 10

data-glean log-only

destination-glean log-only

!

ipv6 dhcp guard policy HOST

ipv6 destination-guard policy

destination

ipv6 mld snooping

IPv6 First Hop Security (Cont.)

• Cisco C3750X switch running IOS version 15.2(1)S

interface GigabitEthernet2/0/1

switchport access vlan 1200

switchport mode access

ipv6 nd raguard attach-policy HOST

ipv6 dhcp guard attach-policy HOST

!

interface Vlan1200

ip address 192.168.12.100 255.255.255.0

ipv6 enable

ipv6 nd cache interface-limit 3 log 15

!

ipv6 neighbor binding logging

ipv6 neighbor binding max-entries 100

ipv6 neighbor binding vlan 1200

2001:DB8:12::/64

IPv6 First Hop Security Results

• Switch successfully blocked RAs and rogue DHCPv6Mar 30 06:37:31.743: %SISF-4-PAK_DROP: Message dropped A=FE80::AC7F:B2F8:DCB8:F739

G=- V=1200 I=Gi2/0/2 P=NDP::RA Reason=Packet not authorized on port

Mar 30 06:38:06.572: %SISF-4-PAK_DROP: Message dropped A=FE80::1EDF:FFF:FEBB:8944

G=- V=1200 I=Gi2/0/2 P=NDP::NA Reason=Packet accepted but not forwarded

Mar 30 06:23:35.902: %SISF-4-PAK_DROP: Message dropped A=2001:DB8:1:3::1 G=- V=1200

I=Gi2/0/1 P=NDP::NA Reason=Address limit per policy reached

Mar 30 06:38:06.572: %SISF-6-ENTRY_CREATED: Entry created A=FE80::1EDF:FFF:FEBB:8944

V=1200 I=Gi2/0/2 P=0005 M=5CFF.340A.F93D

Mar 30 06:19:38.370: %SISF-6-ENTRY_MAX_ORANGE: Reaching 80% of max adr allowed per

policy (10) V=1200 I=Gi2/0/1 M=3C97.0E86.74AD

!

Mar 30 06:38:42.201: %SISF-4-PAK_DROP: Message dropped A=FE80::45B4:32FF:FE67:53 G=-

V=100 I=Et0/0 P=NDP::NA Reason=Advertise while TENTATIVE

Mar 30 06:38:45.923: %SISF-6-ENTRY_CREATED: Entry created A=FE80::45B4:32FF:FE67:53

V=100 I=Et0/0 P=0005 M=

Mar 30 06:38:52.523: %SISF-6-ENTRY_CHANGED: Entry changed A=FE80::45B4:32FF:FE67:53

V=100 I=Et0/0 P=0005 M=

Mar 30 06:38:58.471: %SISF-6-ENTRY_CHANGED: Entry changed A=FE80::45B4:32FF:FE67:53

V=100 I=Et0/3 P=0005 M=45B4.3267.0053

IPv6 First Hop Security Results

• Switch successfully blocked RAs and rogue DHCPv6Switch-1# show ipv6 snoop counter interface gigabitethernet 2/0/2

Received messages on Gi2/0/2:

Protocol Protocol message

NDP RA[14734]

DHCPv6 SOL[191] ADV[1]

Bridged messages from Gi2/0/2:

Protocol Protocol message

NDP

DHCPv6 SOL[191]

Dropped messages on Gi2/0/2:

Feature Protocol Msg [Total dropped]

DHCP Guard DHCPv6 ADV [1]

reason: Message type is not authorized by the policy on this

port, device-role mismatch [1]

RA guard NDP RA [14734]

reason: Message unauthorized on port [14734]

Switch-1#

IPv6 First Hop Security Results

• Switch successfully blocked RAs and rogue DHCPv6Switch-1# show ipv6 snoop counter interface gigabitethernet 2/0/1

Received messages on Gi2/0/1:

Protocol Protocol message

NDP RS[11] RA[2794] NS[51] NA[7031]

DHCPv6 SOL[142]

Bridged messages from Gi2/0/1:

Protocol Protocol message

NDP RS[11] NS[50] NA[15]

DHCPv6 SOL[142]

Dropped messages on Gi2/0/1:

Feature Protocol Msg [Total dropped]

RA guard NDP RA [2794]

reason: Message unauthorized on port [2794]

Snooping NDP NS [1]

reason: Packet accepted but not forwarded [1]

NA [7016]

reason: Address limit per policy reached [7007]

reason: Packet accepted but not forwarded [9]

Switch-1#

IPv6 FHS with IPv6 ACL

• If you don’t have RA Guard on your switch you might be able to configure a Cisco IPv6 Port-based ACL (PACL)

• ipv6 access-list IPV6_PACL

• remark Deny Rogue DHCPv6

• deny udp any eq 547 any eq 546

• remark Deny Rogue RA

• deny icmp any any router-advertisement

• permit ipv6 any any

• !

• interface GigabitEthernet 1/2

• ipv6 traffic-filter IPV6_PACL in

Extension Headers• There are rules for the frequency and order of various

extension headers

• Hop-by-Hop and Destination Options

• Header Manipulation – Crafted Packets

• Large chains of extension headers

• Separate payload into second fragment

• Consume resources - DoS

• Invalid Extension Headers – DoS

• Routing Headers Type 0 – source routing

• Routers can be configured to block RH0

• This is now the default on newer routers

• Firewalls, Windows, Linux and MacOS all block RH0 by default

Layer-3/4 Spoofing

• Spoofing of IPv6 packets is easy

• IPv6 BOGON (Martians) Filtering is required

• Filter traffic from unallocated space and filter router advertisements of bogus prefixes

• Permit Legitimate Global Unicast Addresses

• Unicast Reverse Path Forwarding (Unicast-RPF)

• Don’t block FF00::/8 and FE80::/10 – these will block NDP (NS/NA)

• Hierarchical addressing and ingress/egress filtering can catch packets with forged source addresses

• Tracebacks may prove to be easier with IPv6

Transition Mechanism Threats

• Dual Stack is the preferred transition method.

• You are only as strong as the weakest of the two stacks.

• Running dual stack will give you at least twice the number of vulnerabilities and require almost twice the work to secure.

IPv4 IPv6

Threats Against Translation• Manual Tunnels

• Preferred over dynamic tunnels• Filter tunnel source/destination and use IPsec• If spoofing, return traffic is not sent to attacker

• Dynamic Tunnels• 6to4 Relay routers are “open relays”• Attackers can guess 6to4 addresses easily• ISATAP can have potential MITM attacks• Attackers can spoof source/dest IPv4/v6 addresses

• Translation techniques are susceptible to DoS attacks• NAT prevents IPsec, DNSSEC, Geolocation and other applications

from working• Consuming connection state (CPU resource consumption attack

on ALG)• Consuming public IPv4 pool and port numbers (pool depletion

attack)

IPv6 Firewalls

• Don’t just use your IPv4 policy for your IPv6 policy.

• Don’t blindly allow IPsec or IPv4 Protocol 41 (6in4 tunneled traffic) through the firewall unless you know the tunnel endpoints

• Firewalls have improved their IPv6 capabilities, IPv6 addresses in the GUI, some logs, ability to filter on Extension Headers, Fragmentation, PMTUD, and granular filtering of ICMPv6 and multicast.

• IPv6 firewalls may not have all the same full features as IPv4 firewalls

• UTM/DPI/IPS/WAF/content filtering features may only work for IPv4.

IPv6 Intrusion Prevention• Few signatures exist for IPv6 packets or you have to build

your own using cryptic regular expressions or byte-offset values.

• IPSs should send out notifications when non-conforming IPv6 packets are observed having faulty parameters, bad extension headers, source address is a multicast address.

• Many IPSs don’t inspect packets that are encapsulated (6in4, 6to4, 6in6, ISATAP, Teredo, 6rd, DS-Lite).

• IPv6 support varies greatly in modern IPS systems.

• Talk with your vendor about what you need.

Summary of BCPs

• Perform IPv6 filtering at the perimeter (RFC2827 filtering and Unicast RPF checks).

• Use manual tunnels (with IPsec whenever possible) instead of dynamic tunnels and deny packets for transition techniques not used.

• Use common access-network security measures (IPv6 FHS techniques, RA-Guard, 802.1X, disable unused switch ports, Ethernet port security, MACSec/TrustSec) .

• Strive to achieve equal protections for IPv6 as with IPv4.

• Continue to let vendors know what you expect in terms of IPv6 security features.

RTFM – Read This Fine Manuscript• IPv6 Security, By Scott Hogg and Eric Vyncke,

Cisco Press, 2009.

ISBN-10: 1-58705-594-5

ISBN-13: 978-1-58705-594-2

Questions and Answers

• Scott Hogg

• shogg@gtri.com

• www.hoggnet.com

• Twitter: @scotthogg

• Network World Blog

• http://www.networkworld.com/community/hogg

• Rocky Mountain IPv6 Task Force

• www.rmv6tf.org