PPAP

Perfectly Poison ARP Poisoning

Team19

b05902127 劉俊緯

b05902117 陳柏文

b05902031 謝議霆

What is ARP?

Task: 87 -> 88

140.112.31.87

140.112.31.88

Switch cannot look ip.

So we needs 88's MAC to let switch forward.

src: 140.112.31.87

dst: 140.112.31.88

dst MAC: ???

87:87:87:87:87:87

88:88:88:88:88:88

ARP Request & Reply

140.112.31.87

140.112.31.88

ARP Request

who has 140.112.31.88 ?

87:87:87:87:87:87

88:88:88:88:88:88

ARP Reply

88:88:88:88:88:88 has 140.112.31.88 ?

src ip: 140.112.31.87 src MAC: 87:87:87:87:87:87

dst ip: 140.112.31.88 dst MAC: 88:88:88:88:88:88

What is ARP Poisoning?

ARP Poisoning

140.112.31.87

140.112.31.88

I know 140.112.31.88 => 88:88:88:88:88:88

87:87:87:87:87:87

88:88:88:88:88:88

ARP Reply

89:89:89:89:89:89

has 140.112.31.88

140.112.31.89

89:89:89:89:89:89

89:89:89:89:89:89

How to mitigate ARP Poisoning?

Dynamic ARP Inspection(DAI)

Why not?

  • DAI needs information in Layer 3
    • Must be Layer3 Switch
  • Not flexible

ARP poisoning + MitM
Attack Flow Chart

Environment

  • Layer2 switch
  • Port security
    • Attacker can't fake mac address

1. Everything is fine

2. Attacker send arp reply

3. user update arp table

4. package redirect

5. package redirect

Demo arp poisoning

Monitoring + Patch on L2 switch!

Monitor with Cisco switch

  • Monitor in Cisco
    • Copy all packages from port to destination port

switch

monitor

PC

Monitor with other L2 switch

  • Monitor -> Gateway
  • Firewall

switch

monitor

PC

IP -> multiple MAC?

  • user update arp table
  • Possible reason:
    • change device
    • DHCP
    • attack

1 MAC -> multiple IP?

  • Possible reason:
    • change IP
    • attack

Detect

  • if MAC2 -> IP2 and previous IP1 && IP2 has its MAC1
    • ping IP2 with the MAC1
    • if received
      • ban MAC2

Problem: Broken ARP at normal users

Re-Poisoning!

DEMO PPAP

Q&A