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Introduction to Vulnerability Assessment Labs

Introduction to Vulnerability Assessment Labs. Ge Zhang ge.zhang@kau.se Dvg-C03. Schedule. 3 Attacking methods Password cracking ARP spoofing & sniffing Port Scanning 1 Defense methods Firewall configuration 2 Vulnerability assessment tool Nessus Bastille. Environment.

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Introduction to Vulnerability Assessment Labs

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  1. Introduction to Vulnerability Assessment Labs Ge Zhang ge.zhang@kau.se Dvg-C03

  2. Schedule • 3 Attacking methods • Password cracking • ARP spoofing & sniffing • Port Scanning • 1 Defense methods • Firewall configuration • 2 Vulnerability assessment tool • Nessus • Bastille

  3. Environment • 3 VM images (c:\vmware\valab-ht11)

  4. Password Cracking • Authentication: • Something you know • Something you have • Something you are • Password need to be transferred • Password need to be stored

  5. Brute Force • Attempts all possible combinations of letters and numbers • Possible Solution • Limit amount of unsuccessful logins • Change password often • The length should be at least 8 characters

  6. Dictionary • Type of Brute Force • Only tries possibilities that are likely to succeed • List are derived from dictionary • Possible Solutions • Mix and match numbers, letters, upper and lower case • Avoid passwords based on dictionary words, letter or number sequences, usernames, or biographical information

  7. John the ripper • Traditionally the account information is stored in the /etc/passwd file • The /etc/passwd file is world-readable • Shadow password system stores passwords in the file /etc/shadow which is not world-readable • Have a look on • /usr/share/doc/john-1.7.0.2/EXAMPLES • Then create your own account and password, run “john” again to see the result • useradd [your account] • passwd [your account]

  8. Sniffing • Hub: a hub simply receives incoming packets and broadcasts these packets out to all devices on the network • Adapt promiscuous mode: an adapter can receive all frames on the network, not just frames are addressed to that adapter

  9. Wireshark

  10. Wireshark

  11. Hub v.s. switch • Hub: Layer 1 (physical) • Switch: Layer 2 (data-link)

  12. ARP (Address Resolution Protocol) • MAC address (layer 2) • Global unique • Unchangeable • IP address (layer 3) • Network unique • Changeable

  13. ARP spoofing (cache poisoning) on switch

  14. Preparation • ipconfig /all • Let me know the last number of your ip address and mac address • ping [IP address] –t

  15. Cain

  16. Cain

  17. Cain

  18. Port Scanning • Attackers wish to discover services they can break into. • Whether the service existing? • sending a packet to each port, once at a time. • Based on the type of response, an attacker knows if the port is used. • The used ports can be probed further for weakness. • Well-known: tcp 21, tcp 22, tcp 23, tcp 80 …

  19. Nmap • -sT (scanning by TCP connections) • -sS (SYN scanning) • -sU (UDP scanning) • -sV (Version detection) • -O (OS fingerprinting) • -T[0-5] (time interval) • -f (fragmenting)

  20. Nmap

  21. Nmap • Zenmap: graphical interface

  22. Firewall • A set of related programs that protects the resources of a private network or a host from external environment. • A mechanism for filtering network packets based on information contained within the IP header.

  23. IPtables 3 default chains • input Used to control packets entering the interface. (The packets will be ended in this machine) • output Used to control packets leaving the interface. (The packets are originated from this machine) • forward Used to control packets being masqueraded, or sent to remote hosts.

  24. IPtables • iptables command [match] [target] • Command: -A, -I, -D, -F, -L • Match: -p [protocol], -s [source IP], -d [destination IP], -i [interface], --sport [source port], --dport [destination port] • Target: -j [ACCEPT/DROP/LOG…] • Example: • iptables –I INPUT –p ICMP –j DROP • iptables –I INPUT –p ICMP –icmp-type 0 –j ACCEPT • Our task: restrict all inbound traffic, except SSH requests on port 22. However, any outgoing requests should not be affected.

  25. Nessus • Remote vulnerability scanner • Nessus will • Perform over 900 security checks • Accept new plugins to expand new checks • List security concerns and recommend actions to correct them

  26. Nessus • Client/server architecture • Server: perform checking • Client: Front-end • Can test unlimited amount of hosts in each scan

  27. Nessus

  28. Nessus

  29. Bastille • Operating System Hardening • Remove unnecessary processes • Setting file permissions • Patching and updating • Setting networking access controls • Generate your own hardening policy • Can be run manually to provide advice and information

  30. Bastille • Assessment mode: bastille -a

  31. Bastille • Configuration mode: bastille -x

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