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Home Computer Security and Privacy Seminar


Hardware based most routers (Linksys, D-Link, etc) also include a router ... Linksys' Instant Broadband EtherFast Cable/DSL Firewall Router with 4-Port ... – PowerPoint PPT presentation

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Title: Home Computer Security and Privacy Seminar

Home Computer Security and Privacy Seminar
  • a presentation byBob Cook
  • Discovery Owners Association, Inc

Special Thanks to Pat Crispen
Seminar Topics
  • Phishing
  • Internet Shopping
  • Firewalls and Testing
  • Computer Virus
  • Spyware
  • Windows Software Updates
  • Internet Explorer
  • Misc Security concerns
  • WIFI security considerations

Cooks Law of Computer Security
  • Don't buy a computer.
  • If you do buy a computer, don't turn it on.
  • If you must turn it on, protect yourself from
    disaster by following the recommendations in this

Tick tock
  • Once online, your computer is vulnerable to
    attack from viruses, worms, and even criminals.
  • How long do you have between connection and
  • On average, 20 minutes.
  • And if you have a cable or DSL connection, you
    have less time than that.

Source http//isc.sans.org/survivalhistory.php
Common types of home computer security breaches
  • Viruses, worms, and Trojan horses
  • Code exploits
  • Malware adware and spyware
  • Phishing attacks

Impact of home computer security breaches
  • Loss or compromise of your data
  • Identity theft
  • Loss of income
  • Legal consequences
  • Stolen money from your bank account

Scared yet?
  • The internet can be a dangerous place for both
    computers and users.
  • Fortunately, there are some simple ways to
    protect both your computer and yourself.

Phishing Attacks
  • You get an email advising that you need to update
    your account information. A link is provided
    that takes you to a website that looks very
    official, but it really is a pirate site seeking
    your personal info.
  • Never click on link, type in URL manually
  • Use spoofstick (http//www.corestreet.com/spoofsti

Internet Purchases
  • Only purchase from known vendors
  • Use a special credit card or PayPal account to
    limit exposure
  • Never buy anything from a foreign venders
  • Always use a secure link (https) for paying (Most
    browsers display a key or lock when on a secure

Part One Firewalls
  • What they are and why you absolutely need one
    well, actually, two before you even THINK about
    connecting your computer to the internet.

Mmm worms and crackers.
  • Connect to the internet and two things will
    quickly target and attack your computer Worms
    and crackers.
  • Worms are a type of computer virus that, using
    automatic file sending and receiving features
    built into most computers, tries to infect other
    computers including yours over a network.
  • Many worms include backdoors that give crackers a
    way to easily break into your computer at a later
  • And if the worms dont get you, the crackers will.

How crackers find you
  • How do worms and crackers find your computer in
    the first place?
  • Worms automatically/randomly search the internet
    looking for every unprotected computer they can
  • Every semi-competent cracker and script kiddie
    has software that
  • Scans thousands of internet connections looking
    for Windows file and printer shares.
  • Scans for known vulnerabilities, holes, and
    unsecured services in Windows, Mac OS, Linux,
    VM-CMS, etc.
  • Exploits those known vulnerabilities.
  • Cracks Windows passwords.
  • And so on.

Protecting your computer
  • To protect your computer, you must hide it from
    the internet.
  • If the worms and crackers cant see your
    computer, they hopefully wont attack you.
  • How do you hide your computer? Use a firewall.

Consumer Firewall
  • Hardware based most routers (Linksys, D-Link,
    etc) also include a router
  • Software based ZoneAlarm, EZFirewall, etc

What is a firewall?
  • A firewall is either hardware or software that
    stands between your computer or home network
    and its internet connection and provides access
    controlit determines what can and cannot pass.
  • Its just like the firewall in your car.
  • Your cars firewall keeps the bad stuff from your
    engine like heat and exhaust out of your
    passenger cabin.
  • But it isnt impervious. It has holes in it to
    let the good stuff like the steering column and
    the brakes through.

What is a firewall?
  • A good firewall, like your cars firewall, keeps
    the bad stuff out and lets the good stuff
  • How? Well most consumer firewalls offer a
    combination of
  • Computer stealththey hide your computer from the
    worms and crackers scans.
  • Intrusion blockingthey make it harder but not
    impossible for worms and crackers to break in.

IP addresses
  • When you connect your home computer to the
    internet, the internet connects to your computer.
  • Every computer connected to the internet has its
    own, unique internet address like
  • Your ISP automatically assigns the internet
    address to your computer from a pool of addresses
    the ISP maintains.
  • When you disconnect or at some regular interval
    with cable modem and DSL connections, that
    address goes back into the ISPs pool of
    addresses and is given to someone else.

If a cracker knows your internet address, he can
probe your computer for vulnerabilities.
  • Hardware firewalls use something called Network
    Address Translation or NAT which, among other
    things, hides your computer from the worms and
  • You physically connect your home computers to
    the firewall and connect the firewall to the
  • The firewallnot your home computerconnects to
    the internet and is assigned a publicly-visible
    internet address by your ISP.

Hiding behind a wall of fire
  • Your firewall automatically assigns your
    computer a private internet addresses.
  • Only your firewall knows what your computers
    private address is.
  • The private address is not visible to anyone on
    the Internet nor is it directly accessible from
    the internet.
  • Since the worms and crackers cant see your
    computers address, it is harder for the worms
    and crackers to scan your computer for
  • So, hopefully, the worms and crackers move on to
    someone elses computer.

Communicating with the Internet
  • Your firewall becomes your computers
    intermediary on the internet. All traffic must
    go through it.
  • When you request something from the internet, the
    firewall pretends that it made the request, not
    your computer.

Keeping worms and crackers out
  • Since the internet never even sees your computer,
    theres nothing for the worms or crackers to
    probe or attack other than your firewall.
  • And your firewall is just a dumb box.

Stateful packet inspection
  • In addition to using NAT to hide your computer,
    a firewall also uses stateful packet inspection
    or SPI to block intruders.
  • It only allows connections that you originate.
  • All other connections are automatically blocked
    at the firewall.

Why firewalls ROCK!
  • Firewalls protect your home computer from worms
    and crackers through a combination of
  • Computer stealth using NAT.
  • Intrusion blocking using stateful packet
  • Gosh, is there anything firewalls cant do?

What a firewall cant do
  • Well, actually, a consumer firewall cant
  • Fix operating system or software vulnerabilities
  • A firewall may block some exploits coming in from
    the internet, but the vulnerabilities will still
    be there
  • Thats why patch management is so important
  • Protect your computer from viruses.
  • A firewall may block internet worms, but it wont
    block viruses attached to emails, hidden in files
    you download from the internet or Kazaa, etc.
  • Virus protection is a job for your antivirus
    program, not a firewall.

Theres more
  • A consumer firewall also cant
  • Protect your computer from spyware.
  • Block pop-up ads.
  • Block spam.
  • Completely keep crackers out.
  • Protect you from doing stupid stuff to your

But, if you are looking for simple computer
stealth and basic intrusion blockingand trust
me, you areyou need a firewall.
Dont I already have a firewall?
  • How can you tell if you have a firewall and/or if
    it is working properly?
  • Go to grc.com and run Shields Up.
  • This is a free, online tool from security guru
    Steve Gibson.
  • Shields Up checks file sharing, common ports, all
    service ports, messenger spam, and browser
  • If Shields Up can see you, so can the crackers.
  • You either dont have a firewall or it isnt
    configured properly.

Which one?
  • Should you get a hardware firewall or a software
  • If you have a cable modem, satellite, or DSL
    connection, you need both a hardware firewall and
    a software firewall.
  • If you have a dial-up connection or an internal
    broadband modem a modem physically built into
    your computer, you only need a software firewall
  • But thats only because I dont know of any
    reasonably-priced external hardware firewalls
    that work with internal modems.

Why both?
  • Hardware firewalls have an Achilles heel they
    for the most part assume that ALL internet
    traffic originating from your computer is safe.
  • But, if you accidentally double-click on a
    virus-infected file,
  • Your computer will be infected with that virus.
    Remember, hardware firewalls cant protect you
    from either viruses or doing stupid stuff.
  • That virus is more than likely going to try to
    use your computer and your internet connection to
    infect other computers.

Hardware Firewall Limitations
  • So your computer is now a virus-spewing zombie.
  • BUT, remember, your hardware firewall still
    trusts your computer.
  • Your computer is flooding the internet with
    thousands of viruses, worms, or spams, and your
    hardware firewall doesnt notice, care, or even
    bother to tell you.

How software firewalls work
  • Software firewalls actually, personal software
  • Constantly run in the background.
  • Block bad stuff from the internet the stuff that
    somehow magically makes it past the hardware
  • Warn you when a program on your computer tries to
    access the internet.
  • You decide whether or not that program will be
    allowed to access the internet.

So in our zombie example, the software
firewallNOT the hardware firewallwould catch
the flood of viruses before they even left your
In the simplest terms
  • Hardware firewalls protect your computer from the
  • Software firewalls
  • Are a second layer of defense behind your
    hardware firewall.
  • Protect both your computer from the internet AND
    the internet from your computer.
  • Warn you when something fishy is happening on
    your computer.
  • So now can you see why I recommend running both a
    hardware AND a software firewall?

Hardware firewalls
  • Now for the bad news Hardware firewallsstand-alo
    ne boxes that do nothing but block intrudersare
    both complicated and expensive.
  • Ciscos cheapest firewall the PIX 501 is
    approximately US400 Source pricewatch.com
  • But two important features of hardware
    firewallsNAT and SPIare built into most
    hardware routers which are a LOT cheaper.
  • Linksys Instant Broadband EtherFast Cable/DSL
    Firewall Router with 4-Port Switch/VPN Endpoint
    BEFSX41 is approximately US70 Source

Over the router and through the woods
  • My suggestion?
  • Before you connect your computer to the Internet,
    go to your nearest technology store or big box
  • Buy a cable/DSL router from Linksys my
    favorite, D-Link, Netgear, Belkin, or SMC for

Image courtesy Linksys.com
uadmin padmin?
  • Read the instructions that come with your router
  • Crackers know the default administrators userid
    and password for every router and firewall and
    server and operating system and... ever made.
  • Check out http//www.phenoelit.de/dpl/dpl.html if
    you dont believe me.
  • Also, using the instructions, make sure to
    disable remote administration in your routers

Software firewalls
  • Now that I spent US50 of your hard-earned money
    on a router, let me save you some money.
  • The best software firewalls in my humble
    opinion are absolutely free.
  • ZoneAlarm http//www.zonelabs.com/
  • Sygate Personal Firewall http//smb.sygate.com/pr

Training your firewall
  • You need to train the free version of ZoneAlarm
    and other software firewalls.
  • By default, ZoneAlarm blocks everything on your
    computer from accessing the internet.
  • You have to manually tell ZoneAlarm which
    programs to let through.
  • Fortunately, this is really simple to do Just
    check out http//www.tinyurl.com/27wcz for
    instructions on how to install and train

XP Firewall
  • Windows XP comes with its own firewall, so we XP
    users can breathe easy, right?
  • WRONG!
  • If you have Windows XP Home or Professional, your
    built-in software firewall is both horrible and
    most likely disabled.
  • XP SP2 Firewall only protects incoming traffic.
  • Do NOT use XP firewall!

  • Once youve installed a hardware and/or software
    firewall youre in the clear, right?
  • Not exactly. Youre SIGNIFICANTLY better
    protected from exploits and network intrusions
    than most people, but theres still more you need
    to do.

Part Two Exploits
  • What they are, where they come from, and how to
    manage them

Some questionable stats from Secunia
  • XP Professional
  • 46 security advisories issued in 2003-2004
  • 48 involved some sort of remote online attack.
  • 46 involved granting system access to a cracker.
  • Mac OS X
  • 36 security advisories issued in 2003-2004
  • 61 involved some sort of remote attack.
  • 32 involved granting system access to a cracker.

Source Secunia as posted in http//slashdot.org
The truth of the matter
  • Computer security isnt just a PC- or Mac-only
  • EVERY operating system and EVERY software
    application has vulnerabilities, especially
  • Crackers can use these vulnerabilities to
  • Read or even delete every file on your computer
  • Infect your computer with a virus
  • Use your computer to attack another computer or
  • Do a whole bunch of other nasty things.

But there are some simple ways to keep the
crackers especially the script kiddies at bay.
Repairing the damage
  • Repairing the damage from an exploit could be as
    simple as deleting or replacing corrupt data or
    as complicated as a deep-level format of your
    hard drive.
  • The repair path depends on the exploit.
  • This may be a job for a professional repair
  • The BEST way to repair the damage caused by an
    exploit is to close the holes before they are

Closing the holes
  • When a vulnerability is found, operating system
    and software manufacturers eventually/hopefully
    release something called a patch.
  • A patch is simply a software update meant to fix
    problems, bugs, or the usability of a previous
    version of an application. Source Wikipedia
  • Download and install the patch and your computer
    is hopefully no longer susceptible to that
    particular vulnerability.

Why are patches so important?
  • When a new patch is released, an unintended
    consequence is that the bulletin announcing the
    patch also announces the vulnerability to
  • Crackers count on the fact that you wont get the
    patchyour computer will continue to be
  • And the time between bulletin and exploit is

You cant completely protect your computer from
every exploit, but you can keep the exploits at
bay by practicing simple patch management.
How to patch Windows
  • When Microsoft finds a security hole in Windows
    or Internet Explorer, they usually/eventually
    release a patch called a Critical Update.
  • In Internet Explorer, go to Tools Windows
  • Click on Scan for updates.

How to patch Windows
  • Download and install only the Critical Updates
    and Service packs.
  • Ignore the other updates.
  • Keep running Windows Update until it tells you to
    go away.
  • To see a complete catalog of all Microsoft
    Critical Updates for Windows 9X and NT, go to

The NEW Windows Update
  • There are now two Windows Updates
  • Version 4 for Windows 95, 98, 98SE, ME, and NT
  • Version 5 for Windows XP and 2000
  • When you run Windows Update, Microsoft sniffs
    your computer and automatically redirects you to
    the correct version.

Mambo Number 5
  • When you run Windows Update v.5 on XP or 2000 for
    the first time, choose Express Install.
  • This only gives you the critical updates and
    security updates.
  • By default, Automatic Updates are turned on.

Manually run Windows Update at least once a week.
  • Your computer should, by default, automatically
    check for updates. Thats cool, but also run the
    update manually just to be safe.

To patch Microsoft Office
  • In Windows XP or 2000, just run the new Windows
  • In older versions of Windows, go to
    officeupdate.microsoft.com and click on Check
    for Updates
  • Mac users need to go to http//www.microsoft.com/m
  • Have your Office installation disk nearby in case
    the update needs to sniff the disk.

Patching other programs through Check for
  • Open the program you want to patch and, under the
    Help menu, look for Check for Updates,
    Updates, Check for Upgrade, or something
  • This will either
  • Automatically check for and install any software
    patches you are missing
  • Take you to a web site where you can download the
    necessary patches.

Manually patching your software
  • If the Help menu doesnt have a built-in update
    feature, choose About the name of the program
    in the Help menu and write down the exact version
    number of the program.
  • Usually its an integer and a combination of
    decimals like 7.0.1
  • Go to the software manufacturers web site and
    look for Downloads, Upgrades, Support, or
    something similar.

Manually patching your software
  • Compare your softwares version number to the
    version number available online.
  • If the decimals of the online version number are
    larger than yours, download and install the
    appropriate patch.
  • If the integer is larger, youll need to buy a
    new version of the program.

  • Once youve installed a hardware and/or software
    firewall and regularly patched your operating
    system and programs youre in the clear, right?
  • Not exactly. Youre certainly better protected
    from exploits than most people, but theres still
    more you need to do.
  • You need to test your firewall, and check for
    viruses and spyware
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