Absolute PC Security and Privacy.pdf

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in front of the URL.) • Downloading music and movie files from a media archive site • Downloading music and movie files from other users, via peer-to-peer file-swapping services (Napster, KaZaA, Audiogalaxy, etc.) • Downloading files from messages in Usenet newsgroups • Downloading files from messages in other online bulletin boards All these operations are just different ways to transfer a file from one computer to another over the Internet. They all take place while you’re online, and all put you at some risk of receiving a file that contains a virus—with the risk being lower if you download from official manufacturer sites and recognized file download archives. There is also the possibility that you could inadvertently download a virus-infected file from a Web site. Web page developers often include JavaScript and ActiveX code in their HTML pages that tries to run a script or download a file. If this happens, you’ll see a dialog box asking if you want to run the script or download the file. If you answer no, you’re safe; if you answer yes, you get the file downloaded to your system—and if the file includes a virus, your system gets infected. So, while it’s a very different transmission method, this approach still relies on you downloading an infected file to your hard disk. In Attachments to E-Mail Messages Probably the most common method of infection today is via e-mail. Since more users are using e-mail to send files to one another, it only makes sense that e-mail is also used to transfer infected files. The danger isn’t in the e-mail message itself. (At least not usually; see the sidebar “Infected E-Mail Messages” for another take on this.) The danger is in any file attached to the message. You send files via e-mail by attaching those files to a standard e-mail message. The files aren’t embedded into the message; they just piggyback along for the ride. When you receive e-mail with a file attached, you have a choice—you can ignore the attachment, you can save the file to your hard disk, or you can open the file right then and there. It’s when you open the attached file that you run the risk of infection. When you run a file, you also run any embedded virus code. So when you open an e-mail attachment, you could be infecting your system with a virus. If you’re one of those users who automatically open all attached files, then your risk of being infected in this manner is high. If, on the other hand, you don’t open strange or unrequested attachments, then you substantially lower your risk. Note Learn more about e-mail viruses in Chapter 7, “E-Mail, Chat, and Instant Messaging Viruses.” Infected E-Mail Messages It’s possible—although much less common—for an e-mail message itself to contain a virus.
If your e-mail program is configured to automatically display messages in a separate preview pane, that preview will display any pictures or fancy fonts coded into the message using HTML. Since HTML code can also reference ActiveX and JavaScript code (for controls and such), and since ActiveX and JavaScript code can include virus code, it’s possible to unknowingly launch a virus just by reading the contents of an e-mail message. In reality, this is not a common means of infection, for a number of reasons. First, you can configure your e-mail program not to run ActiveX and JavaScript controls, which defeats the infection mechanism. Second, you can configure your e-mail program not to display the preview pane, which also defeats the infection mechanism. More important, this is a much more difficult way to spread a virus, from the standpoint of the virus writer. It’s much, much easier, and much more effective, just to attach the virus file to a standard e-mail message. (Why embed the virus when you can attach it with much less effort) So embedding within an e-mail message is a relatively unpopular and ineffective way to spread a computer virus. In Files Sent via Chat or Instant Messaging A growing problem exists with files sent from user to user via Internet chat and instant messaging (IM) sessions. With both chat and IM, you participate in real-time text-based conversations with other users. It’s becoming more common for users you chat with to send you files—pictures of themselves, documents they’re working on, even just “something you should see.” The problem is that any file someone sends you can contain a virus—especially if that user is someone you just “met” online, and don’t really know. As with all other files you download, you don’t run any risk by simply downloading files that you’re sent in chat and IM sessions. The risk comes after you save the file; it’s when you open the file that the infection can occur. The risk of being infected via chat or IM is similar to the risk you run with e-mail attachments. If you thoughtlessly accept and run all files sent to you when chatting, your risk of infection is high. If you’re more cautious about the files you accept, you lower your risk substantially. Note Learn more about e-mail viruses in Chapter 7. In Document Files with Macros It used to be that only program files could contain computer viruses. That changed in the mid- 1990s, when Microsoft started including full-blown programming capability in its Office applications (Word, Excel, et al.). The programming language was a variation of Visual Basic, called Visual Basic for Applications (VBA), and was used to create macros, automate certain operations, design custom interfaces, and so on. Unfortunately, VBA can also be used to write virus code.
Page 1 and 2: Absolute PC Security and Privacy Mi
Page 3 and 4: infected files from his system. Som
Page 5 and 6: You don’t have to read Absolute P
Page 7 and 8: Unfortunately, this problem doesn
Page 9 and 10: demonstrated the first experimental
Page 11 and 12: Some computer viruses are created w
Page 13 and 14: Unfortunately, that’s a bit of a
Page 15 and 16: Note In reality, you can create a v
Page 17 and 18: The right tools include one of the
Page 19: There’s still a danger of receivi
Page 23 and 24: The list starts with executable fil
Page 25 and 26: .exe, you think you’re dealing wi
Page 27 and 28: elatively easy to track down—and
Page 29 and 30: You also increase your risk if you
Page 31 and 32: Table 2.2: Virus Risk Potential for
Page 33 and 34: If you’ve ever been hit by a comp
Page 35 and 36: Overview The two earliest forms of
Page 37 and 38: Figure 3.2: The boot process as aff
Page 39 and 40: Your PC is now Stoned! Further evid
Page 41 and 42: OBJ, LIB, and Source Code Viruses A
Page 43 and 44: Magistr This is a memory-resident p
Page 45 and 46: While boot sector viruses are relat
Page 47 and 48: • Microsoft Excel (XLS and XLW fi
Page 49 and 50: For a period of time in the mid- to
Page 51 and 52: exit the program. Since many macro
Page 53 and 54: Overview As you learned in Chapter
Page 55 and 56: Different Types of Script Viruses I
Page 57 and 58: Does your name add up to 666 Enter
Page 59 and 60: Links This VBS worm sends itself as
Page 61 and 62: Win95.SK Win95.SK is a virus that,
Page 63 and 64: Figure 5.2 : Configuring Outlook Ex
Page 65 and 66: administrator. Disabling Scripting
Page 67 and 68: Attach the file to an e-mail from a
Page 69 and 70: situation. Indeed, most attackers u
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FREE SURF fwd: Joke Hello Kitty I C
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Figure 6.1 : The contents of a typi
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• PestPatrol (www.safersite.com)
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Common Worms The number of worms in
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Nimda Nimda was briefly discussed i
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type of worm from your computer sys
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(typically using Trojan techniques,
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(As you can see, HTML e-mail is ide
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If you never open any e-mail attach
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Virus Protection in Outlook Express
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Figure 7.6 : Disabling the Preview
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chat session, all other infected us
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In addition, most antivirus program
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You are infected with a virus that
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How to Remove an Instant Messaging
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when an individual takes an existin
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New Pictures of Family This virus h
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For example, the Naked Wife worm re
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This chapter also provides a look a
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Program Approx. Price Manual Disk &
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F-Prot Antivirus contains one of th
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Note Panda Antivirus Platinum is av
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Note Command on Demand is available
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Figure 9.2 : Scanning for viruses w
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Figure 9.5 : Configuring Norton's A
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6. When the Scan And Deliver Wizard
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Figure 9.8 : The results of a Virus
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Figure 9.10 : Configuring VirusScan
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Continue Scanning Records any infec
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To understand how new viruses show
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Figure 10.2 : How integrity checkin
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Figure 10.4 : How sandboxing identi
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obsessive about this sort of thing,
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look at a list of files in My Compu
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software is more deliberate, and it
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Your antivirus program will also sc
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Update Your E-mail Program Everythi
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• Virus Alerts Mailing List (www.
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While we're on the topic of switchi
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To further reduce your risk of infe
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4. Go online to your antivirus soft
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General File Cleaning When you run
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Once you know which files you need
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Reinstalling System Files Unfortuna
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of the attacker to do specific harm
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One reason for the recent increase
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How to Initiate a Computer Attack H
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On the morning of February 7th, the
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It's likely that you'll first notic
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• Activate password protection to
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The people who attack computers in
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impersonation attack is always limi
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Note The following are relatively t
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data stream and 'becoming' one of t
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As you learned in Chapter 11, 'Prev
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That's because the longer you're on
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Start by reconfiguring Windows for
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If this is too extreme a measure, y
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Computer theft is a particular prob
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typical P2P connection. No servers,
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and search for 'Weezer.' You then s
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Instant messaging presents a unique
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And that's not the only security pr
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your permission if you accept the '
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Security Risks-On the Other End Unl
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• Firewall software • Firewall
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either inside the firewall or repla
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crackers on drive-by "war runs" to
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Figure 18.3 : Filtering incoming tr
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80. Your firewall, then, can be con
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state, recorded during installation
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distributes ZoneAlarm Pro, for abou
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Figure 18.7 : Configuring the Inter
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Figure 18.10 : Viewing recent attac
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Figure 18.13 : Configuring firewall
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Despite your best precautions, you
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Figure 19.1 : Using Windows XP's Se
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the signatures of known intrusion t
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We Americans value our privacy. We
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It also reinforces the general warn
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User Profiling What good is all thi
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Tip If you can't find a site's priv
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Yahoo! automatically receives and r
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Figure 20.1 : Look for these seals
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Whether these activities are permis
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Of course, if you're one of the cor
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• Buy personal information from '
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• For any credit card, loan, or b
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• Any U.S. attorney or state atto
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When you want to protect your priva
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There are many ways you can be defr
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situation. The simple fact is that
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Another potential area of online fr
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feedback. You can also read the ind
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Money Orders and Cashier's Checks A
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The Nigerian Letter scam started ou
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• If you think your bank accounts
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And stalking can lead to worse offe
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It can also be dangerous. Many stal
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How to Protect Your Children Online
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Spyware is like a Trojan horse, in
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visited. This information is then r
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In many ways, this is like a tradit
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Using Antispy Software An easier wa
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Spyware that is installed and used
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Cookie Management The reason you pr
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You can also adjust the privacy lev
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Figure 24.5 : Removing stored cooki
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Read on to learn more about these r
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they’re easier to remember. If yo
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Note The RSA cryptography algorithm
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Fortunately, Outlook Express automa
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Fortunately, we can use digital tec
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Personal Digital IDs for e-mail can
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Some possible forms of biometric id
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Figure 26.1 : Making Web page reque
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• Stealther (www.photono-software
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“dummy” IDs, messages can still
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communities, if you will. These fre
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subscribe to on a regular basis. Tw
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Figure 27.1 : A plain-text spam mes
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The problems posed by these types o
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So all those e-mails you get from L
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as to be virtually unusable.) Spamm
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For this reason, many individuals a
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Probably the easiest way to obtain
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Don’t Unsubscribe You should also
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o o 4. Click Summary. 5. Click Save
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If you’re resigned to the fact th
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At the same time, create a second,
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On the national level, the FTC has
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But in an age where too many Intern
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Ms. Fonda did visit North Vietnam i
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which exploded and burned down her
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Nigerian Letter Scam Probably the m
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typical Web page. In addition, the
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(You can change the width and heigh
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4. Scroll down to the Scripting sec
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Because banner ads are just graphic
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Sometimes you open e-mail ads witho
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Of course, forced frames aren’t t
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To this end, there are several orga
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to filter out some degree of legiti
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Figure 31.3 : Configuring Internet
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OneKey OneKey (www.onekey.com) is a
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authentication The process of deter
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An electronic credential that confi
Page 366 and 367:
IP half scan A type of pre-attack p
Page 368 and 369:
A secret key that can be used, eith
Page 370:
An attack resulting from the attack
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