Surprise ARP Attack Draws Attention

It isn't often that old hacking methods make significant news, but an ARP attack received widespread attention earlier this week, more so for the perceived target than for the actual attack itself.

In the seven layer OSI networking model, the second layer includes support for protocols like Address Resolution Protocol (ARP), which is what helps networking devices work out which specific piece of hardware should receive network traffic being sent to a particular network address.

Known attacks against this protocol include ARP spoofing, which allows an attacker who carries out a successful attack to completely intercept or otherwise manipulate traffic to a target system and completely remove it from a network.

In the recently reported attack, H D Moore's Metasploit Project had all Internet traffic redirected to a defaced page, announcing that a group called sunwear had hacked the site for fun. When H D Moore initially received reports of the defacement, he was able to verify that the site itself was completely functional, which hinted at a network-based attack at some point upstream of his server.

Given that it was affecting all network traffic headed for Metasploit, it had to be a close network node, and it turned out that another system in the same VLAN that held the Metasploit systems had been compromised and then used to carry out an ARP spoofing attack against Metasploit and the 200-plus other sites on the same VLAN.

H D Moore was able to address the issue by hardcoding his service provider's router MAC address into his ARP cache, but it didn't solve the problem for the other sites affected (who would have to carry out similar steps to overcome the issue or rely upon the service provider to do so).

According to a posting from Moore to the Full Disclosure mailing list, the ARP spoofing attack coincided with a broad denial of service attack (syn floods) against various services associated with the site.

The group claiming responsibility for the attack are a well-known Chinese group, but there doesn't appear to be much more to the attack than an effort to make a public statement of capability.

Some observers have pointed out that older style attacks and probes have largely been forgotten in the rush to focus on application-level attacks and threats, so this case should be a good wakeup call for most security service providers. It also highlights the risks that can be associated with outsourcing data and hosting services to external providers