The Computer Clarity Blog

Unfortunately, many users are victims of viruses, worms, or Trojan horses. If your computer gets infected with malicious code, there are steps you can take to recover.

How do you know your computer is infected?

Unfortunately, there is no particular way to identify that your computer has been infected with malicious code. Some infections may completely destroy files and shut down your computer, while others may only subtly affect your computer’s normal operations. Be aware of any unusual or unexpected behaviors. If you are running anti-virus software, it may alert you that it has found malicious code on your computer. The anti-virus software may be able to clean the malicious code automatically, but if it can’t, you will need to take additional steps.

What can you do if you are infected?

1. Minimize the damage – If you are at work and have access to an IT department, contact them immediately. The sooner they can investigate and clean your computer, the less damage to your computer and other computers on the network. If you are on your home computer or a laptop, disconnect your computer from the internet. By removing the internet connection, you prevent an attacker or virus from being able to access your computer and perform tasks such as locating personal data, manipulating or deleting files, or using your computer to attack other computers.

2. Remove the malicious code – If you have anti-virus software installed on your computer, update the virus definitions (if possible), and perform a manual scan of your entire system. If you do not have anti-virus software, you can purchase it at a local computer store. If the software can’t locate and remove the infection, you may need to reinstall your operating system, usually with a system restore disk that is often supplied with a new computer. Note that reinstalling or restoring the operating system typically erases all of your files and any additional software that you have installed on your computer. After reinstalling the operating system and any other software, install all of the appropriate patches to fix known vulnerabilities.

How can you reduce the risk of another infection?

Dealing with the presence of malicious code on your computer can be a frustrating experience that can cost you time, money, and data. The following recommendations will build your defense against future infections:

• Use and maintain anti-virus software – Anti-virus software recognizes and protects your computer against most known viruses. However, attackers are continually writing new viruses, so it is important to keep your anti-virus software current.

• Change your passwords – Your original passwords may have been compromised during the infection, so you should change them. This includes passwords for web sites that may have been cached in your browser. Make the passwords difficult for attackers to guess.

• Keep software up to date – Install software patches so that attackers can’t take advantage of known problems or vulnerabilities. Many operating systems offer automatic updates. If this option is available, you should enable it.

• Install or enable a firewall – Firewalls may be able to prevent some types of infection by blocking malicious traffic before it can enter your computer. Some operating systems actually include a firewall, but you need to make sure it is enabled.

• Use anti-spyware tools – Spyware is a common source of viruses, but you can minimize the number of infections by using a legitimate program that identifies and removes spyware.

• Follow good security practices – Take appropriate precautions when using email and web browsers so that you reduce the risk that your actions will trigger an infection.

As a precaution, maintain backups of your files on CDs or DVDs so that you have saved copies if you do get infected again.

Computer Clarity

Staying Safe on Social Network Sites

What are social networking sites?

Social networking sites, sometimes referred to as “friend-of-a-friend” sites, build upon the concept of traditional social networks where you are connected to new people through people you already know. The purpose of some networking sites may be purely social, allowing users to establish friendships or romantic relationships, while others may focus on establishing business connections.

Although the features of social networking sites differ, they all allow you to provide information about yourself and offer some type of communication mechanism (forums, chat rooms, email, and instant messenger) that enables you to connect with other users. On some sites, you can browse for people based on certain criteria, while other sites require that you be “introduced” to new people through a connection you share. Many of the sites have communities or subgroups that may be based on a particular interest.

What security implications do these sites present?

Social networking sites rely on connections and communication, so they encourage you to provide a certain amount of personal information. When deciding how much information to reveal, people may not exercise the same amount of caution as they would when meeting someone in person because

• The internet provides a sense of anonymity.
• The lack of physical interaction provides a false sense of security.
• They tailor the information for their friends to read, forgetting that others may see it.
• They want to offer insights to impress potential friends or associates.

While the majority of people using these sites do not pose a threat, malicious people may be drawn to them because of the accessibility and amount of personal information that’s available. The more information malicious people have about you, the easier it is for them to take advantage of you. Predators may form relationships online and then convince unsuspecting individuals to meet them in person. That could lead to a dangerous situation. The personal information can also be used to conduct a social engineering. Using information that you provide about your location, hobbies, interests, and friends, a malicious person could impersonate a trusted friend or convince you that they have the authority to access other personal or financial data.

Additionally, because of the popularity of these sites, attackers may use them to distribute malicious code. Sites that offer applications developed by third parties are particularly susceptible. Attackers may be able to create customized applications that appear to be innocent while infecting your computer without your knowledge.

How can you protect yourself?

• Limit the amount of personal information you post – Do not post information that would make you vulnerable, such as your address or information about your schedule or routine. If your connections post information about you, make sure the combined information is not more than you would be comfortable with strangers knowing. Also be considerate when posting information, including photos, about your connections.
• Remember that the internet is a public resource – Only post information you are comfortable with anyone seeing. This includes information and photos in your profile and in blogs and other forums. Also, once you post information online, you can’t retract it. Even if you remove the information from a site, saved or cached versions may still exist on other people’s machines.
• Be wary of strangers – The internet makes it easy for people to misrepresent their identities and motives. Consider limiting the people who are allowed to contact you on these sites. If you interact with people you do not know, be cautious about the amount of information you reveal or agreeing to meet them in person.
• Be skeptical – Don’t believe everything you read online. People may post false or misleading information about various topics, including their own identities. This is not necessarily done with malicious intent; it could be unintentional, an exaggeration, or a joke. Take appropriate precautions, though, and try to verify the authenticity of any information before taking any action.
• Evaluate your settings – Take advantage of a site’s privacy settings. The default settings for some sites may allow anyone to see your profile. You can customize your settings to restrict access to only certain people. However, there is a risk that even this private information could be exposed, so don’t post anything that you wouldn’t want the public to see. Also, be cautious when deciding which applications to enable, and check your settings to see what information the applications will be able to access.
• Use strong passwords – Protect your account with passwords that cannot easily be guessed. If your password is compromised, someone else may be able to access your account and pretend to be you.
• Check privacy policies – Some sites may share information such as email addresses or user preferences with other companies. This may lead to an increase in spam. Also, try to locate the policy for handling referrals to make sure that you do not unintentionally sign your friends up for spam. Some sites will continue to send email messages to anyone you refer until they join.
• Use and maintain anti-virus software – Anti-virus software recognizes most known viruses and protects your computer against them, so you may be able to detect and remove the virus before it can do any. Because attackers are continually writing new viruses, it is important to keep your definitions up to date.

Children are especially susceptible to the threats that social networking sites present. Although many of these sites have age restrictions, children may misrepresent their ages so that they can join. By teaching children about internet safety, being aware of their online habits, and guiding them to appropriate sites, parents can make sure that the children become safe and responsible users.

Computer Clarity

Understanding Hidden Threats: Corrupted Software Files

What types of files can attackers corrupt?

An attacker may be able to insert malicious code into any file, including common file types that you would normally consider safe. These files may include documents created with word processing software, spreadsheets, or image files. After corrupting the file, an attacker may distribute it through email or post it to a web site. Depending on the type of malicious code, you may infect your computer by just opening the file.

When corrupting files, attackers often take advantage of vulnerabilities that they discover in the software that is used to create or open the file. These vulnerabilities may allow attackers to insert and execute malicious scripts or code, and they are not always detected. Sometimes the vulnerability involves a combination of certain files (such as a particular piece of software running on a particular operating system) or only affects certain versions of a software program.

What problems can malicious files cause?

There are various types of malicious code, including viruses, worms, and Trojan horses. However, the range of consequences varies even within these categories. The malicious code may be designed to perform one or more functions, including

• interfering with your computer’s ability to process information by consuming memory or bandwidth (causing your computer to become significantly slower or even “freeze”)
• installing, altering, or deleting files on your computer
• giving the attacker access to your computer
• using your computer to attack other computers

How can you protect yourself?

• Use and maintain anti-virus software – Anti-virus software recognizes and protects your computer against most known viruses, so you may be able to detect and remove the virus before it can do any damage. Because attackers are continually writing new viruses, it is important to keep your definitions up to date.
• Use caution with email attachments – Do not open email attachments that you were not expecting, especially if they are from people you do not know. If you decide to open an email attachment, scan it for viruses first. Not only is it possible for attackers to “spoof” the source of an email message, but your legitimate contacts may unknowingly send you an infected file.
• Be wary of downloadable files on web sites – Avoid downloading files from sites that you do not trust. If you are getting the files from a supposedly secure site, look for a web site certificate. If you do download a file from a web site, consider saving it to your computer and manually scanning it for viruses before opening it.
• Keep software up to date – Install software patches so that attackers cannot take advantage of known problems or. Many operating systems offer automatic updates. If this option is available, you should enable it.
• Take advantage of security settings – Check the security settings of your email client and your web browser. Apply the highest level of security available that still gives you the functionality you need.

Computer Clarity

Social Engineering/Phishing Email

Social engineering is a strategy for obtaining information people wouldn’t normally divulge, or prompting an action people normally wouldn’t perform, by preying on their natural curiosity and/or willingness to trust. Perpetrators of scams and other malicious individuals combine social engineering with email in a number of ways.

Phishing Email

Phishing emails are crafted to look as if they’ve been sent from a legitimate organization. These emails attempt to fool you into visiting a bogus web site to either download malware (viruses and other software intended to compromise your computer) or reveal sensitive personal information. The perpetrators of phishing scams carefully craft the bogus web site to look like the real thing.

The email is sent as spam to tens of thousands of recipients. Some, perhaps many, recipients are customers of the institution. Believing the email to be real, some of these recipients will click the link in the email without noticing that it takes them to a web address that only resembles the address of the real institution. If the email is sent and viewed as HTML, the visible link may be the URL of the institution, but the actual link information coded in the HTML will take the user to the bogus site.

For example:

Visible link: http://www.yourbank.com/accounts/

Actual link to bogus site: http://itcare.co.kr/data/yourbank/index.html

The bogus site will look astonishingly like the real thing, and will present an online form asking for information like your account number, your address, your online banking username and password—all the information an attacker needs to steal your identity and raid your bank account.

What to Look For

Bogus communications purporting to be from banks, credit card companies, and other financial institutions have been widely employed in phishing scams, as have emails from online auction and retail services. Carefully examine any email from your banks and other financial institutions. Most have instituted policies against asking for personal or account information in emails, so you should regard any email making such a request with extreme skepticism.

Phishing emails have also been disguised in a number of other ways. Some of the most common phishing emails include the following:

• Fake communications from online payment and auction services, or from internet service providers – These emails claim there is a “problem” with your account and request that you access a (bogus) web page to provide personal and account information.
• Fake accusation of violating Patriot Act – This email purports to be from the Federal Deposit Insurance Corporation (FDIC). It says that the FDIC is refusing to ensure your account because of “suspected violations of the USA Patriot Act.” It requests you provide information through an online form to “verify your identity.” It’s really an attempt to steal your identity.
• Fake communications from an IT Department – These emails will attempt to ferret passwords and other information phishers can use to penetrate your organization’s networks and computers.
• Low-tech versions of any of the above asking you to fax back information on a printed form you can download from a (bogus) web site.

The Anti-Phishing Working Group maintains a helpful phishing archive. The archive catalogues reported phishing scams and presents not only the content of the phishing email, but also screen captures of the bogus web sites and URLs used in the scams. A review of several of the phishing scams catalogued in the archive can provide you insight into how these scams work and arm you with the information you need to avoid falling for them. You can find the Anti-Phishing Working Groups phishing archive at the following address:

http://www.antiphishing.org/phishing_archive/phishing_archive.html

Computer Clarity