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A Client Side Defense against Address Resolution Protocol (ARP) Poisoning

A Client Side Defense against Address Resolution Protocol (ARP) Poisoning. George Mason University INFS 612, Spring 2013 Group #3 (C. Blair, N. Eisele , N. Rehman , T. Troy). Topics. Abstract ARP Introduction Problem Related Research Works Pros / Cons of Other Solutions

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A Client Side Defense against Address Resolution Protocol (ARP) Poisoning

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  1. A Client Side Defense against Address Resolution Protocol (ARP) Poisoning George Mason University INFS 612, Spring 2013 Group #3 (C. Blair, N. Eisele, N. Rehman, T. Troy)

  2. Topics • Abstract • ARP Introduction • Problem • Related Research Works • Pros / Cons of Other Solutions • Our Proposed Solution • Pseudo-code • Pros / Cons of Our Solution • Summary • Questions?

  3. Abstract • ARP Poisoning can cause loss of privacy and security vulnerabilities • Many scholarly works were researched, key weakness were highlighted in their research • Within our constrained scope, our solution to ARP Poisoning overcomes the weaknesses of previously researched solutions

  4. ARP Introduction • ARP is used on local Ethernet networks to map an IP address to a MAC address • ARP was first created in the early 80s, intended as an efficient address resolution mechanism (security was not a priority) • Each host maintains their own ARP table which stores IP-MAC mapping • ARP communicates using Requests and Replies • ARP Replies are automatically accepted without authentication • ARP Poisoning exploits the processing of ARP Replies

  5. Normal ARP Exchange Host A wishes to communicate with Host B 1 ARP cache is checked Host A 5 ARP entry is added 2 ARP request is sent 4 ARP reply is sent Host B Host C 3 ARP entry is added

  6. ARP Frame Packet

  7. ARP Cache Table Typical OS X ARP Cache Table

  8. ARP Poisoning Attacker wishes to intercept traffic to and from host AClassic “Man-in-the-Middle” attack Host A 3 Outbound traffic passes through attacker 1 Gratuitous ARP to Host A saying “I am the router” Gratuitous ARP to router saying “I am Host A” 2 Router Attacker Inbound traffic alsopasses through attacker 4

  9. Secure Server (Gouda) • Add secure server to Ethernet • Add Invite-Accept and Request-Reply protocols • Protocols use: • Timeouts to counter message loss • Shared secrets to counter message modification • Nonces to counter message replays • Cons: • Requires adding an additional secure server and backup server • Requires two additional protocols • Additional communication traffic • Permanent entries are restrictive

  10. Enhanced ARP with Trusted Authority (Hammouda and Trablesi) 1 Registers with Router using unique 10 byte “fingerprint” Host A 9 3 2 If accepted, stores IP-MAC-fingerprintinformation, replies with hash 1 3 Sends ARP request for Host B withfingerprint fragment 8 2 4 4 Creates ARP Traffic database entry with ARP Request information Router 7 • Accept: Store IP-MAC-Fingerprint information Reply Accepted with fingerprint hash • Reject: Fingerprint already in use Reply Rejected, Host must resend • Drop: IP already registered Drop Request, most likely spoof 5 6 Verification Request 6 If ok, notifies B, removes A’s request entry, and adds an entry for B’s reply 5 Host B 7 Sends ARP Reply Sends Verification Request, Router removes B’s reply entry and responds 8 9 Adds Host B’s MAC Address to cache

  11. Our Proposed Solution • Assumptions: • Unsecured LAN • Network must use DHCP • DHCP Server resides on Internet Gateway box • Constraints: • Can not modify Protocol • Can not modify any external machine (host or router)

  12. Our Proposed Solution DHCP Message Format • Process begins at startup or user initiation. • Listens for a network connection and captures all DHCP traffic from Port 68. • If packet is a DHCP Reply, extract the IP and MAC address for own machine and IP address for gateway. • Additionally extract gateway MAC address from sender’s frame source hardware address field. • Delete own ARP cache. • Make static entry in ARP cache with extracted information. • Initiate a gratuitous ARP Reply containing own information at set intervals (default = 500 ms).

  13. Our Proposed Solution //call init() on host start up or manually.init() {booleanDHCPframeFound=false ; Frame cFrame = new frame(); while(networkInterfaceExists) { while(!DHCPframeFound) { cFrame.cDHCP = UDPpacket_listener(port 68); if (cDHCP.isDHCP_reply) { System.delete_ARPtable();System.addARP(STATIC, cDHCP.getGtwyIP(),cFrame.getGtwyMAC()); PacketTimerarpM = create_message_repeater(500); arpM.sendGratuitousARP(NetIface.IP, NetIface.MAC); DHCPframeFound=true ; } } }}

  14. Pros & Cons Pros: •No additional hardware needed. •No administrative costs. •Theoretically easy to develop and distribute. •Minimal computer resources required. •Scalable. Cons: •Can only be used in a DHCP network. •Requires DHCP server on the same machine as internet gateway. •Extra network traffic. •Does not secure peer-to-peer communication. •Gateway may not allow  gratuitous ARP. • A race condition could exist if an attacker continuously attempts to poison the internet gateway’s cache with the host’s IP and the attacker’s MAC.

  15. Summary • ARP was designed to be efficient. • Our solution overcomes the weaknesses of other solutions while preserving the original efficiency.

  16. Questions

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