Transcript EE579T-Class 6A - Electrical & Computer Engineering

EE579T
Network Security
6: Vulnerability Assessment
Prof. Richard A. Stanley
Spring 2005
© 2000-2005, Richard A. Stanley
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Overview of Tonight’s Class
• Review last week’s lesson
• Look at network security in the news
• Vulnerability assessment
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Last time...
• SSL provides a means for secure transport
layer communications in TCP/IP networks
• SSL is a commonly used protocol,
developed by Netscape, but ubiquitously
used in browsers, etc.
• The key element of SSL is the handshake
protocol
• SET not widely used for credit transactions,
but the dual signature it introduced is useful
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Security in the News
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T-Mobile security
ChoicePoint
DNS spoofing attacks
Online banking--$90K sent to Latvia?
Mydoom (again!)
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What do all these security issues
have in common?
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Thought for the Day
“When computers (people) are networked, their power
multiplies geometrically. Not only can people share all that
information inside their machines, but they can reach out
and instantly tap the power of other machines (people),
essentially making the entire network their computer.”
Scott McNeely, CEO Sun Microsystems
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Is this quote for real or
is it for marketing?
• What is typical PC bus speed?
• What sort of network data transfer rates can
be attained?
• What does this mean for the future of
networked computing?
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Risks and Vulnerabilities
• Risks are “just there”
• Vulnerabilities occur due to design choices
we make along the way
• They are not the same thing!
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Vulnerability Assessment
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What is it?
Why do we care?
Whose job is it?
How good a job do we have to do?
How can we describe vulnerabilities?
– OVAL
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Warning!
• In this lecture, we will discuss techniques for
enumerating and attacking networks. This
discussion is intended to help you understand how
to protect networks, and is not a recommendation
for or approval of this sort of activity.
• Under no circumstances should you scan or
otherwise probe a network without the explicit
authorization of its management. Doing so could
violate U. S. Federal law (18 USC § 1030).
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How To Rob a Bank
• Just walk in and demand the money
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Where is the bank?
How do you know there is any money?
Where to park the getaway car?
Are there any guards or surveillance devices?
Will you need a disguise?
What kinds of things might go wrong?
What if they say “NO?”
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Success Requires Planning
• Whether robbing a bank or breaching
network security, you need to plan ahead
• Planning ahead is known as vulnerability
assessment
– Acquire the target (case the joint)
– Scan for vulnerabilities (find the entry points)
– Identify poorly protected data (shake the doors)
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Information in Plain Sight
• Lots of valuable information is just lying
around waiting to be used
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telephone directories
company organization charts
business meeting attendee lists
promotional material
• The Internet has made having a company
web page the measure of being “with it”
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Target: FBI
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?
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You get the idea
• There is a lot of information out there, and it
is readily available to anyone
• Good intelligence usually consists of open
source material properly collated
• Law enforcement used to have special
access to this sort of information--now it’s
out on the ‘net
• Network access speeds up the rate at which
good intelligence can be collected
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Determine Your Scope
• Check out the target’s web page
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physical locations
related companies or entities
merger/acquisition news
phone numbers, contact information
privacy or security policies
links to other related web servers
check the HTML source code
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Refine Your Search
• Run down leads from the news, etc.
– Search engines are a good way
• FerretSoft
• Dogpile
• Google
– Check USENET postings
– Use advance search capabilities to find links back to
target
• Search on “worcester polytechnic security” gives ~ 32,400 hits
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Use the Government
• EDGAR
– SEC site (www.sec.gov/edgarhp.htm)
– Search for 10-Q and 10-K reports
– Try to find subsidiary organizations with
different names
• Think about what your organization has on
databases available to the public
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Zero In On The Networks
• InterNIC
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http://www.internic.net/
Organization
Domain
Network
Point of contact
• www.networksolutions.com
• www.arin.net
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Other Sources
• Sam Spade for Windows
– freeware
• Netscan Tools
– Single copy price = $249
• Ipswitch.com
– WhatsUp Pro = $1,495
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Query on Found Data
• POC
– May be (often is) POC for other domains
• Query for email addresses -- here are a few
from @wpi.edu (harder to do than earlier)
Amiji, Murtaza (MA3608) [email protected] (508) 831-5395
Baboval, John (JBJ116) [email protected] XXX-XXXX
Ballard, Richard (RBS722) [email protected] 508-831-6731
Barnett, Glenn S (GSB14) [email protected] (315)475-5920
Bartelson, Jon (JB12891) [email protected] (508) 831-5725 (FAX) (508) 831-5483
Berard, Keith (KB2414) [email protected] (508)754-4502
Blank, Karin (KBJ257) [email protected] 203-762-0532
Blomberg, Adam (AB5417) [email protected] 508-755-7699
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Query the DNS
• Insecure DNS configuration can reveal
information that should be kept confidential
• Zone transfers are popular attack
methodologies
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nslookup often used
pipe output to a text file
review the text file at your leisure
select potential “good targets” based on data
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Map Network Connectivity
• traceroute
– Unix and Win/NT
– tracert in NT for file name legacy reasons
– Shows hops from router to destination
• Graphical tools exist, too
– VisualRoute
– www.visualroute.com
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Detailed Scanning
• Network ping sweeps
– Who is active?
– Automated capabilities with some tools
• ICMP queries
– Reveal lots of information on systems
• System time
• Network mask
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Port Scanning
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Identify running services
Identify OS
Identify specific applications of a service
Very popular
Very simple
Very dangerous
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Port Scan Types
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Connect Scan--completes 3-way handshake
SYN--should receive SYN/ACK
FIN--should receive RST on closed ports
Xmas tree--sends FIN, URG, PSH; should receive
RST for closed ports
• Null--turns off all flags; target should send back
RST for closed ports
• UDP--port probably open if no “ICMP port
unreachable” message received
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Identify Running Services
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nmap
netcat
Udp_scan (and others from SATAN)
Using SYN scan is usually stealthy
Beware of DoS results
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OS Detection
• Stack fingerprinting
– Vendors interpret RFCs differently
• Example:
– RFC 793 states correct response to FIN probe is none
– Win/NT responds with FIN/ACK
• Based on responses to specific probes, possible to
make very educated guesses as to what OS running
– Nmap database so accurate, it is used in commerical
products (e.g. eEye Retina scanner)
– Automated tools to make this easy!
• Nmap
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Enumeration
• Try to identify valid user accounts on poorly
protected resource shares, e.g. on Windows-based
systems
– net view
• lists domains on network
• can also list shared resources
– nltest -- identifies primary & backup domain controllers
– SNMP
– open a telnet connection
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Automated, Graphical Tools
• Can trace network topology very accurately
– ID machines by IP, OS, etc.
– Makes attack much easier
• No shortage of possible tools
– Frequent additions to list
– One source:
http://www.slac.stanford.edu/xorg/nmtf/nmtf-tools.html
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Actual Scan Results--Win2K
• Performed using Internet Security Scanner
• Part of the IIS suite of programs
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Can scan NT/2000/XP and Unix systems
Runs only on NT/2000
Scan range (i.e., addresses) user settable
Sample vulnerability report
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Many Other Scanners
• eEye Retina Scanner
– http://www.eeye.com/html/resources/tours/retina/index.html
• Nessus
– Unix-based system and network scanner
• NeWT
– Windows port of Nessus with graphical frontend
– http://www.tenablesecurity.com/products/newt.shtml
• …and lots more. Google is your friend.
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Summary
• Attacking a network is no different from robbing a
bank; you have to plan if you expect to be
successful
• There are three basic steps to planning, which is
called vulnerability assessment:
– Acquire the target (case the joint)
– Scan for vulnerabilities (find the entry points)
– Identify poorly protected data (enumeration)
• This applies if you are inside or outside the
protected perimeter!
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Homework - 1
1. Identify and describe how you would
enumerate resources on a Unix network,
similar to the discussion in class of
enumeration on Windows/NT/2000/XP
2. You are the network administrator. How
would you defend against the threats of
target acquisition and vulnerability
scanning?
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