IPv6 Pen Testing

By Michael Messner

If you have enabled IPv6 on your network without considering basic security issues, you might have opened up a hole for attackers. In this article, we demonstrate a successful attack on a server via IPv6 and explain how the popular security tools handle IPv6.

Although the “next generation” IPv6 Internet protocol can already look back on more than 10 years of history, many companies are only now starting to migrate to the new version. Some experts have already begun to point out that IPv6 security has some unexpected complications for admins who are accustomed to IPv4 networks. One such under-mentioned problem is the need to lock down or turn off IPv6 services that might be running on an IPv4 or a dual IPv4/IPv6 network. Some modern systems enable IPv6 by default. Even if your network is primarily focused on IPv4, it is a good idea to pay some special attention to IPv6 in your pen testing. You might discover that your systems are vulnerable to exploits in IPv6 that aren’t available (or don’t appear) through conventional IPv4 pen tests.

In this article, I take a brief look at some IPv6 testing modules available through the Metasploit framework. In this case, I set up a scenario for my tests within our security testing lab; however, these techniques will help you search out other exploits hidden on your transitional IPv4/IPv6 mixed network.

Looking Around

All recent operating systems are capable of using the IPv6 protocol and often enable it by default. On Linux, you can verify that IPv6 is enabled with a simple test using  ifconfig or ip (Listing 1). The output for the interface configuration should contain at least one inet6 entry. If an IPv6-enabled router exists on the internal network, the system might already be configured with a global address in addition to the link-local address.

Listing 1: ifconfig and ip

01 root@bt:~# ifconfig -a
02 eth0      Link encap:Ethernet  HWaddr 00:0c:29:7c:e7:6a
03           inet addr:192.168.11.138  Bcast:192.168.11.255  Mask:255.255.255.0
04           inet6 addr: fe80::20c:29ff:fe7c:e76a/64 Scope:Link
05 [...]
06 root@bt:~# ip -6 addr
07 [...]
08 1: lo:  mtu 16436
09     inet6 ::1/128 scope host
10        valid_lft forever preferred_lft forever
11 [...]
12 2: eth0:  mtu 1500 qlen 1000
13     inet6 fe80::20c:29ff:fecf:6aba/64 scope link
14        valid_lft forever preferred_lft forever

The presence of an inet6 entry doesn’t automatically mean the computer is accessible from external addresses. The scope link in line 4 of Listing 1 means that the address is only used on the local subnet; it is not routed beyond router or network boundaries. Listing 2 shows what the configuration looks like when the network contains an IPv6-capable router.

Listing 2: Global Scope

inet6 addr: 2001:4dd0:fd42:3:20c:29ff:fe7c:e76a/64 Scope:Global**
[...]
inet6 addr: fd44:2011:1021:0:20c:29ff:fe7c:e76a/64 Scope:Global**
[...]
inet6 addr: fe80::20c:29ff:fe7c:e76a/64 Scope:Link**

A simple test of the IPv6 functions is to ping6 to the loopback interface:

root@bt:~# ping6 ::1 -c1
PING ::1(::1) 56 data bytes
64 bytes from ::1: icmp_seq=1 ttl=255 time=0.052 ms
--- ::1 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.052/0.052/0.052/0.000 ms

Just as with IPv4, you can ping the broadcast address (in IPv6, this is FF02::1; all the systems on the local network respond to this). Consequently, the following simple command already offers an initial overview of the local network:

root@bt:~# ping6 ff02::1%2 | cut -d\  -f4
fe80::20c:29ff:fecf:6aba:
fe80::20c:29ff:fe5c:e4b6:
fe80::20c:29ff:fef5:b6b0:
fe80::20c:29ff:fe01:95e3:
[...]

If you sort the output, remove duplicate entries with uniq, and redirect the results to a text file, you already have a good basis for further analysis.

IPv6 and Metasploit

Many well-known analysis tools are now ready to work with IPv6 systems. You can use Nessus, Nmap, and Wireshark to analyze IPv6-capable networks. Alive6, for instance, offers several tools for analyzing possible IPv6 vulnerabilities (see the sidebar titled “Alive6”). In this article, however, I will focus on Metasploit.

More...

 Fuente: www.linux-magazine.com