1. Mark Ryan Professor of Computer Security 25 November 2009

2. Insecure PCs buffer overflow virus Trojan horse malware DoS attack
phishing
worm
spam
cross-site scripting
spyware
identity theft
botnets
keyloggers
DNS spoofing

3. β α means β is a possible way to achieve α hardware theft
hardware keylogger
phishing
data theft
(inc. ID theft)
DNS spoofing
XSS
exploit software
vulnerabilities
destruction
(inc. vandalism)
install malware
DDoS
promotion
send spam
create botnet β α
means β is a possible way to achieve α

6. Malware covers all kinds of intruder software
Malware is
software intended to intercept or take partial control of a computer's operation without the user's informed consent.
It subverts the computer's operation for the benefit of a third party.
Also called spyware.
The term “spyware” taken literally suggests software that surreptitiously monitors the user. But it has come to refer more broadly to any kind of malware,
Malware covers all kinds of intruder software
including viruses, worms, backdoors, rootkits, Trojan horses, stealware etc. These terms have more specific meanings.

7. How malware spreads Trojan horse Virus Worm Drive-by
a malicious program that is disguised as useful and legitimate software. Can be part of, or bundled with, the carrier software.
Virus
Self-replicating program that spreads by inserting copies of itself into other executable code or documents.
Worm
Self-replicating program, similar to virus, but is self- contained (does not need to be part of another program). Spreads by exploiting service vulnerabilities.
Drive-by
installs as side-effect of visiting a website; exploits browser vulnerability.
Detail from "The Procession of the Trojan Horse in Troy“, Giovanni Domenico Tiepolo

10. Why does this problem exist?
Why can't engineers create systems that are not vulnerable to this plethora of attacks?
Compare:
cars
aircraft
telephone system
electricity production

11. We have the technology... Attack Defence malware
digital signatures for code
anti-virus software
phishing
encrypted traffic
key certificates
education
DNS spoofing

12. Why does this problem exist?
complexity
immaturity
of technology: “release and fix”
of designers/programmers: bad culture
of users: a new one born every day...
open platform
monoculture

13. Trusting Trust backdoor
How to create an undetectable backdoor:
Change the compiler so that, when compiling the login program, it adds the hard-coded username/password check to the login program.
Thus, the login program source code looks completely normal.
As an extra twist, change the compiler so that, when compiling the compiler, it adds the code to add the code to the login program.
Thus, even if the compiler is recompiled, the backdoor will still be inserted.
And none of the source code reveals the backdoor.
Described in a paper by Ken Thompson, Reflections on Trusting Trust, 1995.

14. What you can do
Don't connect directly to the Internet – connect via a router instead
Don't install anything!
no third-party toolbars, extensions, helpers, freebies
unless you really know where they came from
Be sceptical about from nice people who want to give you $20,000,000 or help you reduce your mailbox usage or help your computer to go faster
Stop using Windows
use Linux, *BSD (or derivative, including Mac OS X)
Update/patch frequently

15. What industry is doing better engineering thin clients cloud computing
trusted computing
protected capabilities outside software control
virtualisation, to support throw-away OS