Transcript Document

Introduction to Vulnerability
Assessment Labs
Ge Zhang
[email protected]
Dvg-C03
Schedule
• 4 Attacking methods
–
–
–
–
Traffic sniffing
ARP spoofing
Password cracking
Port Scanning
• 1 Defense methods
– Firewall configuration
• 2 Vulnerability assessment tool
– Nessus
– Bastille
• Summarizing Report on its learning (1-2 pages)
Environment
• 3 VM images (c:\VMware\valab-ht10\)
– Windows, Fedora (angel), Fedora (devil)
Hub
Hub
Switch
Hub
VM
Hub
Host machine
Sniffing
Hub
shared
Token Ring
• 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
Wireshark
Show capture options
Select network interface
Filters for display
Filters for Capture
Wireshark
Stop
capturing
Captured
datagrams
Datagrams
analysis
Datagrams
in Hex
Sniffing practice
• Surfing with the browser on the host
machine
• Sniff the HTTP traffic using wireshark on
the VM
Hub v.s. switch
• Hub: Layer 1
(physical)
• Switch: Layer 2
(data-link)
Hub
shared
Token Ring
Switch
Dedicated
ARP (Address Resolution Protocol)
• MAC address (layer 2)
– Global unique
– Unchangeable
• IP address (layer 3)
– Network unique
– Changeable
IP address
IP address
ARP
RARP
MAC address
MAC address
ARP spoofing (cache poisoning) on
switch
Who has the IP address 192.163.0.4? Tell
192.163.0.1 with mac: AA
192.163.0.4->DD
I am 192.163.0.4, with mac address DD
192.163.0.1 (AA)
192.163.0.1 (AA)
192.163.0.2 (BB)
192.163.0.2 (BB)
192.163.0.3 (CC)
192.163.0.3 (CC)
192.163.0.4 (DD)
192.163.0.4 (DD)
I am 192.163.0.4, with mac address CC
192.163.0.1 (AA)
I am 192.163.0.1, with mac address CC
192.163.0.2 (BB)
192.163.0.4->CC
192.163.0.1 (AA)
192.163.0.1->CC
192.163.0.2 (BB)
192.163.0.3 (CC)
192.163.0.3 (CC)
192.163.0.4 (DD)
192.163.0.4 (DD)
Preparation
• ipconfig /all
• Let me know the last number of your ip address and mac address
• ping [hostname] –t
Door
Door
ping
ping
ping
ping
Ping
Window
ping
ping
ping
ping
ping
ping
ping
ping
ping
ping
ping
Cain
Select interface
Scan MAC
addresses
Scanned
results
ARP spoofing
configuration
Cain
Add to list for spoofing
Spoof the arp cache for these two hosts to
intercept the conversation between them
Cain
Start ARP Spoofing
Password Cracking
• Authentication:
– Something you know
– Something you have
– Something you are
• Password need to be transferred
• Password need to be stored
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
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
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
• unshadow /etc/passwd /etc/shadow > tmp
• less tmp /*have a look*/
• john tmp
• Then create your own account and password,
run “john” again to see the result
• useradd [your account]
• passwd [your account]
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 …
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)
Nmap
Nmap
• Zenmap: graphical interface
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.
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.
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.
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
Nessus
• Client/server architecture
– Server: perform checking
– Client: Front-end
• Can test unlimited amount of hosts in each scan
www
FTP
Nessus Client
Nessus Server Nessusd
Mail
VoIP
Nessus
Nessus
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
Bastille
• Assessment mode: bastille -a
Bastille
• Configuration mode: bastille -x