1. LOGO
Workshop Attack and Defense – November 2007
Attacking The LAN
Spying The Wire
ATIK PILIHANTO
RISTI TELKOM BANDUNG

2. Global Trend Attack in Local Network
1 Spoofing
2 Man In The Middle
3 Sniffing (Passive)
4 TCP/IP session Hijacking
5 Remote Code Execution
6 Denial of Service (DoS)

3. Spoofing
 Spoofing is sending packet with a forged source with the
purpose of concealing the identity of the sender.
 Spoofing example :
• IP address spoofing
• ARP cache spoofing (ARP cache poisoning)
• Email spoofing
 Spoofing in local network : ARP cache poisoning and IP address
spoofing
ATIK PILIHANTO RISTI TELKOM 2007

4. IP Spoofing in Action

5. Man In The Middle (MiTM)
 Man in The Middle is an attack in which an attacker is able to
read, insert and modify at will, messages between two parties
without either party knowing that the link between them has been
compromised.
 Man in The Middle technique
• Switch port stealing
• ARP cache poisoning
• DNS spoofing
• DHCP spoofing
 Man in The Middle in Local Network : Switch port stealing, DHCP
spoofing, ARP cache poisoning.
RISTI TELKOM 2007
ATIK PILIHANTO

6. Man In The Middle (MiTM)

7. Sniffing (Passive)
 Sniffing is a process intercepting and reading network traffic.
 Sniffing purpose :
• Analyze network problems
• Monitor network traffic
• Spy on other network users and collect sensitive information
 In switched network, sniffing process is usually combined with
Man in The Middle.
ATIK PILIHANTO RISTI TELKOM 2007

8. Sniffing In Action

9. TCP/IP Session Hijacking
 TCP/IP Session Hijacking is an attack in which attacker is able
to hijack or take over an established TCP connection between
two parties.
 In case local network attacking, TCP/IP hijacking can be done by
combining MiTM and active sniffing, inserting RST or FIN,
predicting Initial Sequence Number (ISN), fully compromising
established TCP connection.
ATIK PILIHANTO RISTI TELKOM 2007

10. Remote Code Execution
 Remote code execution allows an attacker to execute any
arbitrary code in a target vulnerable machine.
 Need a flaw or vulnerability in target machine, example :
• DCOM RPC Remote Buffer Overrun ( WINDOWS )
• IPv6 mbuff Remote Buffer Overflow (OpenBSD)
 Remote code execution is usually caused by flaw programming
in operating system, service daemon, or application.
ATIK PILIHANTO RISTI TELKOM 2007

11. Common Programming Mistakes
1 Buffer Overflow
2 Integer Overflow
3 Error Format String
4 SQL injection
5 File Inclussion
6 Cross Site Scripting

12. Remote Buffer Overflow Exploit

13. Denial of Service (DoS)
 Denial of Service is an attack to make a computer resource
unavailable to its legitimate users.
 Denial of Service can be done by attacking
• Protocol weakness : SYN Flooding, ICMP Smurfing
• Service Daemon weakness : Buffer Overflow
• Web Application weakness : WEB2 XSS Worm
 Denial of Service in local network : ARP cache poisoning,
Flooding (SYN/UDP/ICMP)
ATIK PILIHANTO RISTI TELKOM 2007

14. DoS in Vulnerable Daemon

15. Defense
 Defending spoofing attack in LAN is really difficult, but we can
minimize the risk.
 IP spoofing can be used for TCP SYN Denial of Service
• Enabling SYN cookies “sysctl net.ipv4.tcp_syncookies=1”
 ARP cache spoofing can be used for MiTM
• Static ARP entries
• Passive monitoring arpwatch
• Active monitoring ethercap
 Switch port stealing can be used for MiTM
• Port security on the switch
ATIK PILIHANTO RISTI TELKOM 2007

16. Defense
 Manage risk of sniffing and TCP/IP session hijacking
• Using SWITCH rather than HUB
• Defending MiTM attack
• VLAN segmentation
• Encrypted traffic (SSH, SSL, IPsec)
 Manage risk of remote code execution
• Enabling kernel exec shield and random virtual address
• sysctl kernel.exec­shield=1
• sysctl kernel.randomize_va_space=1
• Good firewall policy
• Regular auditing and patching
ATIK PILIHANTO RISTI TELKOM 2007

17. Defense
 Manage risk of Denial of Service
• Good firewall policy
• Regular auditing and patching
ATIK PILIHANTO RISTI TELKOM 2007

18. Discussion
 Discussion ??
 Question ??
 Suggestion ??
ATIK PILIHANTO RISTI TELKOM 2007

19. LOGO
ATIK PILIHANTO RISTI TELKOM 2007