Computer Viruses

In what way? A virus can delete or modify key system files of both installed software and its user-saved documents/spreadsheets/etc, I believe some can even embed themselves into (some) user-saved documents so they can infect other computers. It really depends on what the particular virus is programmed to do.

Why do you ask?

Further to jack of all trades comment, documents (eg MS Word .doc) can contain macros - basically embedded chunks of software - which can do all manner of horrible things (similar to viruses) - the same is true of some CAD drawing files (AutoCAD .dwg etc.).

Please be more specific.

It is possible for a virus to patch any naive .EXE (executable) or .DLL to run the virus in turn. A well behaved virus will only run one instance of itself, no matter how many programs invoke it. Such a virus can stay undetected for years. Such sophisticated versions often have a spyware payload.

If you install an infected program (a typical Trojan Horse example) as the administrator (or, on some OS, run any infected code as the administrator), it is possible for a virus to embed itself in the operation system without detection.

There are many viruses that will invite other species onto your workstation, creating an avalanche. This is when most users notice problems.

Yes they can and are difficult to detect. Some years back I had an accounting package developed for the Dental Laboratories in South Africa that met all the weird governmental requirements. We built in a virus that was activated on breach of license i.e. illegal copying of the program.

The virus affected any algorithms that involved VAT/GST and income tax calculations.. The fix cost 50% more than the program. Very few people check their tax reports manually, but revenue services seem to be quite pedantic about their money and proved to be a wonderful watchdog for our little enterprise....

Theoretically, if you load winword.exe into Photoshop, it could come up looking like the Mona Lisa. (Being a Microsoft product, it would not look nearly as elegant.) The point is, it's ALL just data. Executable files just happen to contain data arranged in a way that produces meaningful results if you tell the CPU to execute it. You could try executing Mona_Lisa.jpg but won't get much except a crash.

Thus, a sufficiently crafty virus can do whatever it wants to your system. If there happens to be a power signal under control of the CPU (USB perhaps), a virus can even fry your hardware. There have been viruses that told the hard drive to beat itself to death, so to speak, by constantly moving the head within its limits. "Fortunately," most viruses are more malicious, and you won't know they're sniping your valuable data.

I worry because I have CAD programs and other documents that I have spent a lot of time developing and would not like to see them go up in smoke. I have Norton, but I still worry. I guess the safest thing is to stay away from the internet altogether and have CAD on a dedicated computer (no ISP).

Two words:

Back ups.

(Even if your backups get infected, you can read the raw data using a virus-proof system like Linux (not virus-proof, but Windows virus-proof).)

Not necessarily! I have a linux computer but it was unable to access and copy my Autocad files when something got into my computer despite running NOD32 with daily checks and frequent scans for a virus. I had to send my computer drive plus infected back-up to a data recovery company. First thing the virus did was erase the electrically programmable BIOS chip on their mother board. They were not amused. Neither was I when I learned how long it would take for them to finally return my drives and send along a new hard drive. Future plans involve running a a second drive that is a duplicate as a mirror drive then do an off line scan of the mirror and switch over ever second day. A full scan of a drive took so long it crippled my work day activity. If a fire wall and NOD32 was unable to keep this virus out what will? I have concluded like Ronseto that the safest plan is to run critical programs on a standalone isolated computer and transfer files by memory stick. Now I use only a Linux machine for browsing and email. it is a PITA but nothing else works.

Mixing operating systems and employing every type of firewall and anti-virus practice available is the best protection, but as you, Google and Adobe have found out, there's a way to destroy any data that ever connects, even by sneaker-net, to an exposed computer. (Though apparently it was simple social engineering that penetrated Google.)

Memory sticks (flash/EEPROM) are dangerous - they are banned by the DOD. Use CD/DVD, or an external hard drive, and scan that thing after every time it touches a system connected to the internet.

Flash drives apparently bypass some of the Windows file system's built-in protections, and external hard drives don't.

There's a neat program called 010 Editor that will let you examine any file or drive at a binary level. Alas, it's only available on Windows, which means a bad virus will infect whatever system you're running it on.

My data was not destroyed but access to the data was. If the hard drive is altered so none of the established software can read how to acces the files, then the data contained on the drive is just so many binary bits. Ronseto and I are probably like the majority of computer users. although we know something about it we are not experts in programming or software manipulation and why should we be? our expertise lies elsewhere. You do not have to be an automotive engineers in order to drive a car In fact you don't even need to be a mechanic. Nor do you need to be an electrician to use an electric stove to cook with. Computers are only appliances and all you should need to know is how to turn it on and use the specific program you want whether it is a word processor a spread sheet or a CAD program. although a house holder should know enough to lock the door at night, he doesn't need to be a trained locksmith or have training as a security chief. While its nice to know about things like your 010 Editor it is of little use to me if cannot read binary. I forgot how to do that forty years ago when we only used 4 and 8 bit processors. When I spoke of using flash drives to transfer files; it was on the assumption it was all done within a system of cleaned and disinfected computers. I can't afford to use an entire 700 MB CD every time I need to move a 2 mb file from the stand alone computer to the internet linked one or vice versa. I would go broke always having to buy more CD and the clutter would prove completely unmanagable. I already have about 600 or so CD to keep track of. Product catalogs, project over views and programs or data CD. It may be a good suggestion but not a practical one. I used to work in an engineering office where we had paper catalogs. then we went paperless and everything is now on disk. It used to be you knew the catalog you wanted was the red or blue one, now all the CD look the same. God help you if the CD ever falls out of the protective sleeve. Now the only way to tell whats on it is to read it. What a time waster.

Dear Ronseto,

you appear (to me at least) to be computer naive. Its not your fault.

You are doing well to worry, but please worry about ALL viruses and the like, Rootkits etc....not just certain ones, they are ALL dangerous to your data.

I personally used Symantec products up to about 3 years ago, but I found they slowed my (very fast for the time dual core AMD) down too much....

I changed to Kaspersky, which incudes a Firewall, Malware scanner, Virus scanner and many other types of scanner! It also appears to only slow down my PC very slightly, in fact I only notice it when I first boot and it downloads an update automatically. A small price to pay...

If you have a DSL Router, then also activate the (usually) built in Hardware Firewall in the router.....(if your Router does not have a hardware firewall, replace it asap)

NOT updating your Windows or other software will also leave you open to possible attacks.

Any Windows version older than XP is paqrticularly open to extra attacks because of "holes" still not fixed and also known by Hackers......and no further support from Bill & Crew.....

As previously mentioned by several posters, you need full backups. There are many methods, but do remember that even a backup can become infected as well.....also, do use the grandfather, father son method.

If using DVDs/CDs, buy only high quality, turn on "Verifying" in your burn program, do not let them see in ANY form of light, in a dark box, or in the burner......make an extra set and put them in a lockable cash box and keep them in a different building.....

This is a very abreviated version of security and backups, but it covers the basics.

I personally would recommend using industry standard 1/2" tape cassettes in an industry standard tape unit, but you need a VERY fast PC in order to drive the tape at the correct fully speed. Anything less will eventually damage the tape itself....

Remember sets of 3 tapes AT LEAST, more is better.

Best wishes and if you have any further questions just ask.