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By making sure a website encrypts your information and has a valid certificate, you can help protect yourself against attackers who create malicious sites to gather your information. You want to make sure you know where your information is going before you submit anything (see Avoiding Social Engineering and Phishing Attacks for more information).

Security Tip (ST04-014) Avoiding Social Engineering and Phishing Attacks

What is a social engineering attack?

In a social engineering attack, an attacker uses human interaction (social skills) to obtain or compromise information about an organization or its computer systems. An attacker may seem unassuming and respectable, possibly claiming to be a new employee, repair person, or researcher and even offering credentials to support that identity. However, by asking questions, he or she may be able to piece together enough information to infiltrate an organization’s network. If an attacker is not able to gather enough information from one source, he or she may contact another source within the same organization and rely on the information from the first source to add to his or her credibility.

What is a phishing attack?

Phishing is a form of social engineering. Phishing attacks use email or malicious websites to solicit personal information by posing as a trustworthy organization. For example, an attacker may send email seemingly from a reputable credit card company or financial institution that requests account information, often suggesting that there is a problem. When users respond with the requested information, attackers can use it to gain access to the accounts.

Phishing attacks may also appear to come from other types of organizations, such as charities. Attackers often take advantage of current events and certain times of the year, such as

  • natural disasters (e.g., Hurricane Katrina, Indonesian tsunami)
  • epidemics and health scares (e.g., H1N1)
  • economic concerns (e.g., IRS scams)
  • major political elections
  • holidays

How do you avoid being a victim?

  • Be suspicious of unsolicited phone calls, visits, or email messages from individuals asking about employees or other internal information. If an unknown individual claims to be from a legitimate organization, try to verify his or her identity directly with the company.
  • Do not provide personal information or information about your organization, including its structure or networks, unless you are certain of a person’s authority to have the information.
  • Do not reveal personal or financial information in email, and do not respond to email solicitations for this information. This includes following links sent in email.
  • Don’t send sensitive information over the internet before checking a website’s security. (See Protecting Your Privacy for more information.)
  • Pay attention to the Uniform Resource Locator (URL) of a website. Malicious websites may look identical to a legitimate site, but the URL may use a variation in spelling or a different domain (e.g., .com vs. .net).
  • If you are unsure whether an email request is legitimate, try to verify it by contacting the company directly. Do not use contact information provided on a website connected to the request; instead, check previous statements for contact information. Information about known phishing attacks is also available online from groups such as the Anti-Phishing Working Group. (See the APWG eCrime Research Papers).
  • Install and maintain anti-virus software, firewalls, and email filters to reduce some of this traffic. (See Understanding FirewallsUnderstanding Anti-Virus Software, and Reducing Spam for more information.)
  • Take advantage of any anti-phishing features offered by your email client and web browser.

What do you do if you think you are a victim?

  • If you believe you might have revealed sensitive information about your organization, report it to the appropriate people within the organization, including network administrators. They can be alert for any suspicious or unusual activity.
  • If you believe your financial accounts may be compromised, contact your financial institution immediately and close any accounts that may have been compromised. Watch for any unexplainable charges to your account.
  • Immediately change any passwords you might have revealed. If you used the same password for multiple resources, make sure to change it for each account, and do not use that password in the future.
  • Watch for other signs of identity theft. (See Preventing and Responding to Identity Theft for more information.)
  • Consider reporting the attack to the police, and file a report with the Federal Trade Commission.

Authors

Cybersecurity and Infrastructure Security Agency (CISA)

If a website has a valid certificate, it means that a certificate authority has taken steps to verify that the web address actually belongs to that organization. When you type a URL or follow a link to a secure website, your browser will check the certificate for the following characteristics:

  1. the website address matches the address on the certificate
  2. the certificate is signed by a certificate authority that the browser

If the browser senses a problem, it may present you with a dialog box that claims that there is an error with the site certificate. This may happen if the name the certificate is registered to does not match the site name, if you have chosen not to trust the company who issued the certificate, or if the certificate has expired. You will usually be presented with the option to examine the certificate, after which you can accept the certificate forever, accept it only for that particular visit, or choose not to accept it. The confusion is sometimes easy to resolve (perhaps the certificate was issued to a particular department within the organization rather than the name on file). If you are unsure whether the certificate is valid or question the security of the site, do not submit personal information. Even if the information is encrypted, make sure to read the organization’s privacy policy first so that you know what is being done with that information (see Protecting Your Privacy for more information).

Can you trust a certificate?

The level of trust you put in a certificate is connected to how much you trust the organization and the certificate authority. If the web address matches the address on the certificate, the certificate is signed by a trusted certificate authority, and the date is valid, you can be more confident that the site you want to visit is actually the site that you are visiting. However, unless you personally verify that certificate’s unique fingerprint by calling the organization directly, there is no way to be absolutely sure.

When you trust a certificate, you are essentially trusting the certificate authority to verify the organization’s identity for you. However, it is important to realize that certificate authorities vary in how strict they are about validating all of the information in the requests and about making sure that their data is secure. By default, your browser contains a list of more than 100 trusted certificate authorities. That means that, by extension, you are trusting all of those certificate authorities to properly verify and validate the information. Before submitting any personal information, you may want to look at the certificate.

How do you check a certificate?

There are two ways to verify a web site’s certificate in Internet Explorer or Firefox. One option is to click on the padlock icon. However, your browser settings may not be configured to display the status bar that contains the icon. Also, attackers may be able to create malicious websites that fake a padlock icon and display a false dialog window if you click that icon. A more secure way to find information about the certificate is to look for the certificate feature in the menu options. This information may be under the file properties or the security option within the page information. You will get a dialog box with information about the certificate, including:

  • Who issued the certificate – You should make sure that the issuer is a legitimate, trusted certificate authority (you may see names like VeriSign, thawte, or Entrust). Some organizations also have their own certificate authorities that they use to issue certificates to internal sites such as intranets.
  • Who the certificate is issued to – The certificate should be issued to the organization who owns the web site. Do not trust the certificate if the name on the certificate does not match the name of the organization or person you expect.
  • Expiration date – Most certificates are issued for one or two years. One exception is the certificate for the certificate authority itself, which, because of the amount of involvement necessary to distribute the information to all of the organizations who hold its certificates, may be ten years. Be wary of organizations with certificates that are valid for longer than two years or with certificates that have expired.

Author

NCCIC

Security Tip (ST04-007) Reducing Spam

What is spam?

Spam is the electronic version of “junk mail.” The term spam refers to unsolicited, often unwanted, email messages. Spam does not necessarily contain viruses—valid messages from legitimate sources could fall into this category.

How can you reduce the amount of spam?

  • Be careful about releasing your email address – Think twice before you respond to any request for your email address, on the web, verbally, or on paper. Spammers can harvest any email address posted on a website. If you give your email address to a company, that information is often entered into a database so that customer information and preferences can be tracked. If these email databases are sold to or shared with other companies, you can receive email that you didn’t request.
  • Check privacy policies – Before submitting your email address online, look for a privacy policy. Most reputable sites will have a link to their privacy policy from any form where you’re asked to submit personal data. You should read this policy before submitting your email address or any other personal information so that you know what the owners of the site plan to do with the information (see Protecting Your Privacy for more information).
  • Be aware of options selected by default – When you sign up for some online accounts or services, there may be a section that provides you with the option to receive email about other products and services. Sometimes there are options selected by default, so if you do not deselect them, you could begin to receive email from those lists as well.
  • Use filters or spam tagging – Many email programs offer filtering capabilities that allow you to block certain addresses or to allow only email from addresses on your contact list. Many ISPs also offer spam tagging services that allow the user the option to review suspected spam messages before they are deleted. Spam tagging can be useful in conjunction with filtering capabilities provided by many email programs.
  • Report messages as spam – Most email clients offer an option to report a message as spam or junk. If your email client has that option, take advantage of it. Reporting messages as spam or junk helps to train the mail filter so that the messages aren’t delivered to your inbox. However, check your junk or spam folders occasionally to look for legitimate messages that were incorrectly classified as spam.
  • Don’t follow links in spam messages – Some spam relies on generators that try variations of email addresses at certain domains. If you click a link within an email message or reply to a certain address, you are just confirming that your email address is valid. Unwanted messages that offer an “unsubscribe” option are particularly tempting, but this is often just a method for collecting valid addresses that are then targeted for other spam.
  • Disable the automatic downloading of graphics in HTML mail – Many spammers send HTML mail with a linked graphic file that is then used to track who opens the mail message. When your mail client downloads the graphic from their web server, the spammers know you’ve opened the message. Disabling HTML mail entirely and viewing messages in plain text also prevents this problem.
  • Consider opening an additional email account – Many domains offer free email accounts. If you frequently submit your email address (for online shopping, signing up for services, or including it on something like a comment card), you may want to have a secondary email account to protect your primary email account from any spam that could be generated. You could also use this secondary account when posting to public mailing lists, social networking sites, blogs, and web forums. If the account start to fill up with spam, you can get rid of it and open a different one.
  • Use privacy settings on social networking sites – Social networking sites typically allow you to choose who has access to see your email address. Consider hiding your email account or changing the settings so that only a small group of people that you trust are able to see your address. (See Staying Safe on Social Networking Sites for more information.) Know that when you use applications on these sites, you may be granting permission for them to access your personal information. So, be cautious about which applications you choose to use.
  • Don’t spam other people – Be a responsible and considerate user. Some people consider email forwards a type of spam, so be selective with the messages you redistribute. Don’t forward every message to everyone in your address book, and if recipients ask that you not forward messages to them, respect their requests.

 

Authors

US-CERT Publications