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If an attacker on the network attempts to use ARP poisoning (spoofing) in order to redirect traffic to his own machine, what mechanisms and techniques are available for tracking the spoofed ARP messages to their source?

Are these techniques effective even when the attacking machine is using a spoofed MAC address (a likely scenario)?

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According to my research on the subject, and running tests there are no quick fixes for tracking the source individual perpetrating this type of attack because of the nature of it. Meaning tracking, but not filtering/blocking. The attack method itself is basically easy to do compared to the scale of other types of attacks out there due to fundamental flaws in network hardware. There are however methods of blocking or tracking (in part) and ways to narrow down the search for an attacker.

One such tool called arpwatch (http://www.securityfocus.com/tools/142) that scans for changes in IP and MAC address then delivers an alert when found. There is a SUSE article on using the tool here: https://www.suse.com/communities/conversations/detecting-arp-poisoning-attacks/

The check into DHCP Snooping and DAI (Dynamic ARP Inspection): http://packetlife.net/blog/2010/aug/18/dhcp-snooping-and-dynamic-arp-inspection/

http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus1000/sw/4_0_4_s_v_1_3/security/configuration/guide/n1000v_security/n1000v_security_12dhcpsnoop.html

Izam is right, it is much easier to detect ARP poisoning than it is to target the attacker. The methods used most often find it when it occurs, or are focused on prevention. Wireshark describes a method of finding a starting point 'for investigation': http://searchsecurity.techtarget.com/video/How-to-use-Wireshark-to-detect-and-prevent-ARP-spoofing

ArpPoisoning.com offers a couple of scripts you run when you log into a server you have concern may be a target. http://www.arppoisoning.com/best-practices-for-defending-against-arp-poisoning-2/ One for linux: https://github.com/alan-reed/ARP-Defense and one for Windows based machines: https://github.com/alan-reed/ARP-Defense/blob/master/defendAPR.bat

The 2 scripts attempt to track the ARP table and compare it live as you are connected, and attempt to repair the ARP table as it is happening.

Another step would be to attempt triangulation (or trilateration) to target the attacker's physical location between multiple access points.

If you have multiple access points, then you have the opportunity when you find the one that is getting the highest level of ARP request traffic, and then by checking the signal strength pinpoint the location of an originating machine.

A security application by Aruba Networks uses triangulation to attempt to locate problems on the network as 'interference sources'. Interestingly enough, they have the same trick in reverse, using ARP poisoning as a defensive weapon: if an 'interference source' is detected it attempts to poison the ARP of the port of the switch used by it and kill its access to the network (page 19 here): http://www.arubanetworks.com/pdf/technology/TB_ProtectTheAir.pdf

Granted I do not have access to a network protected by this automated and multifaceted defensive structure but I would be interested to see how well and how quickly it takes out threats like ARP attacks. Being that it defends against specific points as they are compromised, an assertion could be made that it would give a good general direction in the real environment to look for a physical attacker.

For small networks, it would be better to filter out bad ARP requests and set fixed IP & MAC connections where possible. Then it is much easier to track with fewer connections.

  • From what I understand arpwatch can detect that ARP poisoning has is occurring. My question is about how to locate the machine that is performing the attack, a task complicated by the possibility the the attacker is using a spoofed MAC address as well. – lzam Sep 3 '14 at 0:31
  • Going further with it, there is a very hefty article you must read here: "By using the DHCP Snooping and Dynamic ARP Inspection (DAI) features, multiple types of Layer 2 attacks, including the ARP Poisoning (MITM) attack can be stopped." cisco.com/c/en/us/products/collateral/switches/… – Jeff Clayton Sep 3 '14 at 0:40
  • If I understand correctly, you are saying that if I have Cisco switches configured with DHCP Snooping and Dynamic ARP Inspection, I can use the logs generated by DAI to track down the interface the spoofed ARP messages came through, leading me to the attacker. Is this a Cisco only solution, or are their comparable features on most other enterprise switches? – lzam Sep 3 '14 at 1:54
  • Not saying that they are the only people, just that Cisco is very public about offering that in their routers. – Jeff Clayton Sep 3 '14 at 1:57
  • The information I have read says these things give you 'a good start' in the investigation. But that you also have to look over the logs to see where it started generally. – Jeff Clayton Sep 3 '14 at 2:00
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You may also want to check out IronGeek's ARPFreeze tool: http://www.irongeek.com/i.php?page=security/arpfreeze-static-arp-poisoning

  • This doesn't address the question though. I'm not asking how to prevent, detect, or mitigate, an ARP poisoning attack. I am asking how to track down the source of the attack, once it has been detected. If someone is attacking my network, I need to be able to track them down. – lzam Sep 3 '14 at 17:26
  • You are correct. IronGeek also created an ARPWatch tool: irongeek.com/i.php?page=security/… which was already mentioned in it's Linux/BSD form. But these solutions are more for home/on the road solutions. If you are looking for a commercial style tracking, you can shoot syslogs of almost every type of switch with what MAC address is found on which port of the switch to something like splunk / logstash, from there it's pretty simple to locate and set up alerting on anything that results in MACs on multiple switch ports. – mubix Sep 4 '14 at 0:58
  • @mubix thanks for posting those tools-- more in the repertoire. – Jeff Clayton Sep 4 '14 at 11:37

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