Suspect a Virus?
Where to begin?
Not every system oddity is due to a virus, worm, or bot. Your system may be running sluggish, your hard drive filling unusually quick (not including all that downloading). Do programs crash with no warning? These symptoms could be typical windows, possible conflicting hardware, or incompatibility of certain software that you have installed (shareware, low-budget software -- freeware is normally open source so if there's a bug, somebody's usually fixing it through some means).
Anything obvious is probably not malware. After all, people who write malware want to hide their program's presence. People who write commercial software put icons all over your desktop. Who's going to work harder to go unnoticed?
Other indicators that may, in fact, indicate that there's nothing that you need to worry about, include:
An automated e-mail telling you that you're sending out infected mail. E-mail viruses and worms typically come from faked addresses. Your email address is probably already in a gigantic database if you've been on the internet for more then a month. Appearances in chat rooms, a personal web site, or a forum conversation is all it takes to have your address nicked from the net. Spammers normally pull from these databases at random, so every once in a while you may get such an email "returned" to you.
A frantic note from a friend saying they've been infected, and therefore so have you. This is likely a hoax. It's especially suspicious if the note tells you the virus can't be detected but you can get rid of it by deleting one simple file. Don't be fooled--and don't delete that file. The "Teddy-Bear" Virus is a good example of this. The email wants you to delete a file in your system32 directory. It matches the description, and seems out of place with a little teddy bear for an icon, but it is in fact a very important windows program that is Microsoft Certified.
I'm not saying that you should ignore such warnings. Copy the subject line or a snippet from the body of the e-mail and plug it into your favorite search engine to see if other people have received the same note. A security site may have already pegged it as a hoax.
If you're truly worried about it, you can forward the message to your ISP (usually abuse@yourisp.com, spam@yourisp.com). Make sure to include the header by choosing "view headers" in your email program, then copy and paste it in with the forwarded message. The header shows who sent the message, when they sent it, what server it originated at, and what courier servers touched it along the way through cyberspace.
Sniffing Out an Infection
There are signs that indicate that your PC is actually infected. A lot of network activity coming from your system (when you're not actually using Internet) can be a good indicator that something is amiss. A good software firewall, such as ZoneAlarm, will ask your permission before letting anything leave your PC, and will give you enough information to help you judge if the outgoing data is legitimate. BlackIce is another, but it's a commercial application and may be require a bit more configuration. There is a firewall that comes with Windows, even an improved version in XP Service Pack 2, but lacks the packet inspection. It blocks ports coming in, but it doesn't actually verify if what's going out on the commonly used ports (80, 21, etc)
To put a network status light in your system tray, follow these steps: In Windows XP, choose Start, Control Panel, Network Connections, right-click the network connection you want to monitor, choose Properties, check "Show icon in notification area when connected," and click OK.
If you're interested in what's really going on behind the scenes, you can sniff around further in the Task Manager. Hitting CTRL-SHIFT-ESC in Windows will bring up the Task Manager, which will show you the various processes your system is running. Most, if not all, are legit, but if you see a file name that looks suspicious, type it into a search engine and find out what it is. 30 is normal, 35 is ok, 40 is RIGHT OUT! Well, sometimes... it all depends on how many side processes you have running, system tray icons, etc. The name of the items are the important thing, have a question? Search for the filename in google and you should get multiple sites with the vendor, purpose, and validity of the program.
Want another place to look? In Windows XP, click Start, Run, type "services.msc" in the box, and press Enter. You'll see detailed descriptions of the services Windows is running. Something look weird? Search for it.
Finally, you can delve even deeper by selecting Start, Run, and typing "msconfig" in the box. With this tool you not only see the services running, but also the programs that your system is launching at startup. Again, check for anything weird. (ie runndll.exe /s ePFJKSx1R2.dll)
If any of these tools won't run -- or if your security software won't run -- that in itself is a good sign your computer is infected. Some viruses intentionally disable such programs as a way to protect themselves.
What to Do Next
Once you're fairly sure your system is infected, don't panic. There are steps you can take to assess the damage, depending on your current level of protection.
If it's malware, I recommend Lavasoft: Ad Aware, beware of http://adaware.com => it'll infect you with spyware. The true home of this wonderful tool is at http://lavasoft.com. It's best when used with SpyBot, they complement each other in that they catch what the other may occasionally miss. SpyBot also checks a bit deeper for modified extensions and other not-so-obvious signs of possible malware modification. Again, don't look for it at http://spybot.com -- where it won't infect you with anything (or at least doesn't appear to) it's better to go to the source at http://www.safer-networking.org/en/index.html.
If you don't have any antivirus software on your system (you're just asking for this, aren't you?), or if the software has stopped working, stay online and go for a free scan at one of several Web sites. There's McAfee FreeScan, Symantec Security Check, and Trend Micro's HouseCall. If one doesn't find anything, try two. In fact, running a free online virus scan is a good way to double-check the work of your own local antivirus program. When you're done, buy or download a real antivirus program.
If you have antivirus software, but it isn't active, get offline, unplug wires-- whatever it takes to stop your computer from communicating via the Internet. Then, promptly perform a scan with the installed software.
If nothing seems to be working, do more research on the Web. There are several online virus libraries where you can find out about known viruses. These sites often provide instructions for removing viruses--if manual removal is possible--or a free removal tool if it isn't. Check out GriSOFT's Virus Encyclopedia, Eset's Virus Descriptions, McAffee's Virus Glossary, Symantec's Virus Encyclopedia, or Trend Micro's Virus Encyclopedia.
A Microgram of Prevention
Assuming your system is now clean, you need to make sure it stays that way. Preventing a breach of your computer's security is far more effective than cleaning up the mess afterwards. Start with a good security program, such Trend Micro's PC-Cillin, which you can buy for $50.
Don't want to shell out any money? You can cobble together security through free downloads, such as AVG Anti-Virus Free Edition, ZoneAlarm (a personal firewall), and Ad-Aware SE.
Just make sure you keep all security software up to date. The bad guys constantly try out new ways to fool security programs. Any security tool without regular, easy (if not automatic) updates isn't worth your money or your time.
Speaking of updating, the same goes for Windows. Use Windows Update (it's right there on your Start Menu) to make sure you're getting all of the high priority updates. If you run Windows XP, make sure to get the Service Pack 2 update. To find out if you already have it, right-click My Computer, and select Properties. Under the General tab, under System, it should say "Service Pack 2." Many of the security vulnerabilities that go unpatched are a backdoor for infection by even the simplest devices, the most feared being malicious web sites. They contain scripts which will attempt to install (and often succeed on unpatched systems) a plethora of malware, viruses, and assorted baddies.
Here are a few more pointers for a virus-free life:
Be careful with e-mail. Set your e-mail software security settings to high. Don't open messages with generic-sounding subjects that don't apply specifically to you from people you don't know. Don't open an attachment unless you're expecting it.
If you have broadband Internet access, such as DSL or cable, get a router, even if you only have one PC. A router adds an extra layer of protection because your PC is not connecting directly with the Internet.
Check your Internet ports. These doorways between your computer and the Internet can be open, in which case your PC is very vulnerable; closed, but still somewhat vulnerable; or stealthed (or hidden), which is safest. Visit Gibson Research's Web site and run the free ShieldsUP test to see your ports' status. If some ports show up as closed--or worse yet, open--check your router's documentation to find out how to hide them.
How effective are these precautions? Remember that nothing is impossible. It's always plausible that someone somewhere will be a step ahead of any updates you may have installed, but say on the good side of the tracks, the light side of the internet and you should be fine.
Promises of free games, applications, MP3s, and movies (especially... *ahem*) are a quick trip to a possible electronic hijacking, bringing your computer to the dark side.
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