1. 32-1 Internet Safety/Security Issues

2. 32-2 Trojan/Virus precautions When you run an executable program from an untrusted source you’re opening yourself up to trouble –You turn over complete control of your computer to the whim of an unknown programmer –Virus: A virus infects “real” software by modifying the binary code of executable files to include additional malicious instructions Format your hard drive at a certain date/time Delete essential system files from your computer And of course... –Modify the binary code of other executable files on your hard drive (so it can spread – like a virus) This way, when you give someone else a program you also spread the virus to another computer (a bigger problem in the shareware days) –Trojan Horse: a software program that is advertised as useful or fun software though it only includes malicious instructions Trojans do not (generally speaking) replicate. The additional malicious instructions can also be destructive to files and such but more often include backdoor programs –Backdoor programs open your computer up to complete remote control from the Internet. They can run programs, download or delete files, or send email from your computer

3. 32-3 Antivirus precautions Antivirus software should be used when you run *any* program from the Internet... –Essentially, you need to trust the source of your file. distributed media? Internet downloads? Direct from AOL, Microsoft, Etc “Looks like a legitimate website” “Sure, I can’t read the language, but it claims to be Office 2003, for free!” File Sharing? …

4. 32-4 Trojan/Virus precautions You can scan a program for virii, before you run it, some software can scan a program for trojan programs/backdoors. –You can scan your computer for trojans after the fact, and remove them –Old anti-virus definitions mean you might as well not be scanning at all new virii and trojans are being written and released onto the Internet all the time it’s very difficult to determine what instructions are legitimate and what is malicious –e.g., not all “delete” operations are necessarily malicious by determining virus “signatures” they can be detected

5. 32-5 Hacking Hackers, in this case, try to exploit bugs in software, so they can do things that the original developers did not intend. –Not all hackers are trying to harm … Remember: –All network communication happens with programs –Programs may have bugs; the program may behave badly depending on what the user does –These bugs might open the computer up to vulnerability Example: –Your operating system runs programs that accept connections from other computers for legitimate purposes –This program has a bug which, when receiving too much data, will allow the sender to run any program on the target machine

6. 32-6 Infamous Buffer Overflow Note: You shouldn't be able to be “hurt” from a song, picture, or plain text file – as they contain no executable instructions (?) –After all, some other program reads them as data and doesn’t execute any bits in these data files as instructions. And yet... –Hacked from downloaded images... some programs may not be overly careful about how data is handled –not necessarily a bug, more of a safety concern dealing with invalid input/data »data exists in the same memory as the programs do »clever “hackers” may specially craft malformed data that the program will mishandle resulting in some sort of exploitation

7. 32-7 How to “block” Hackers Keep hackers off your network interface: –Put a firewall between your machine and the outside world Firewall: A set of programs that monitor all communication passing into and out of a corporation’s intranet. –Helps prevent, but doesn’t eliminate, unauthorized acces –Hardware firewall Physical device that sits between your machine and the network Restricts access to your network, keeps people off your machine by proxy –Software firewall Restricts access to your machine, as the above, however it runs on your machine. Fill the security holes on your computer: –Install security updates against “dangerous” software bugs: –http://www.info.apple.com/usen/security/index.htmlhttp://www.info.apple.com/usen/security/index.html –http://www.microsoft.com/security/protect/http://www.microsoft.com/security/protect/

8. 32-8 Spyware/Adware There’s a separate category of “backdoor programs” which aren’t necessarily damaging –Spy-ware: Software that tracks information about the user (without the user’s prior knowledge). Information is usually kept in a large database, and usually re-sold. Ranges from webpage browsing habits to credit card information. –Ad-ware: “Free” software supported by advertising revenue They sell advertising to companies and their software sits on your machine, annoying you with pop-up ads that seem to be coming from no where Further, they sometimes engage in data warehousing, accumulating your personal info, browsing habits, etc and may sell that data as well –Install and use a spyware/adware scanner, remover, blocker (PCSC, links section of the course webpage)

9. 32-9 Problems… World Wide Web: –Snooping: When browsing the internet, your information is passed across many routers across many networks. Users can snoop your traffic, and know what sites you browse, maybe even see your private information. Solution: make sure that secure transfer is enabled for a site before transmitting any private information (https://, lock) –Hacking: Users may hack into the back end systems on which many web stores run – stealing credit card numbers, social security numbers, and more –Malicious plug-ins/exploits: Web sites may contain malicious programs that try to leverage bugs in your web browser to (in some way) compromise your computer Solution? –Keep your browser updated! –Try a less popular browser: Firefox, Opera, etc

10. 32-10 Problems… E-mail –Worm: a software program that replicates itself throughout the internet, usually with the goal of generating lots of bogus internet traffic to crash servers via excessive load. Web Browsers may have critical vulnerabilities which allow malicious code to be run from a website. Since some email clients support rendering email messages in full HTML, you may be emailed a message with the malicious code inside. When you run it, you could be “infected” –Solution: stay up to date with the latest Microsoft Security patches! –Run pine, Mozilla Thunderbird, etc... –Trojan Horse/Virii: software programs that claim to be useful software though also includes malicious instructions –Email messages are send with executable attachments. Users who don’t know any better run them and become infected. –Solution: NEVER run strange attachments! –Phishing: Posing as a legitimate entity, an email directs you to a “spoofed” website where you unwittingly give confidential information to what looks like eBay, Citibank, Paypal, etc...