Computer Security The problem of insecure PCs – and its consequences Why does this problem exist? Solutions – what you can do – what the industry can do Research in Computer Security

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

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

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.

Trojan horse –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 How malware spreads

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

We have the technology...

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

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.

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

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

The Trusted Platform Module p := SHA1(p || x)

Computer security research electronic voting trusted computing privacy in the digital world

Electronic voting

ballot secrecy and coercion resistance usability election verifiability ?

Privacy in the digital world Facebook blogs Gmail Web searches instant messaging Oyster card Government űberdatabase IS P Google Docs

“A face is exposed for AOL searcher no ” From New York Times, August 9, 2006 In August 2006, Buried in a list of 20 million Web search queries collected by AOL and recently released on the Internet is user No The number was assigned by the company to protect the searcher's anonymity, but it was not much of a shield. No conducted hundreds of searches over a three-month period on topics ranging from"numb fingers" to "60 single men" to "dog that urinates on everything." And search by search, click by click, the identity of AOL user No became easier to discern. There are queries for "landscapers in Lilburn", and several people with the last name Arnold. It did not take much investigating to follow that data trail to Thelma Arnold, a 62-year-old widow who lives in Lilburn, GA “

Balancing global security and individual privacy securityprivacy