The Dangers of Phishing
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Phishing is an attack tactic using email. Attackers send out thousands of emails with the intent of getting the recipients either to respond to the email with personal information or to get the recipient to click a link. It’s a tactic used very often, so security professionals need to be aware of phishing and some of the common tactics. Phishing topics are included in many security-related certifications.
Certifications that include Phishing
If you’re planning on taking the CompTIA Security+ exam, or the (ISC)2 SSCP or CISSP, you should be aware of some basics on phishing. Each of these exams may include topics on phishing from these objectives:
- CompTIA Security+
- 2.4 Explain the importance of security related awareness and training
- Threat awareness
- Phishing attacks
- (ISC)2 SSCP
- Malicious Code and Activity Domain
- Identify Malicious Activity
- (ISC)2 CISSP
- Operations Security Domain
- Prevent or Respond to Attacks
Phishing Email Characteristics
Phishing emails share some classic characteristics. While they may implement these characteristics differently, most phishing emails will include the following elements:
- They impersonate a legitimate company. For example, the phishing email may purport to come from PayPal, eBay, Google, Facebook, Bank of America, or another company. They often try to copy the same look and feel of the company they’re impersonating. They include the same graphics, the same fonts, and even many of the same words.
- They present a problem that necessitates the email. A common phishing email starts by stating a problem such as “we’ve noticed suspicious activity on your account” or “we’ve had an excessive amount of fraud so we are updating our security practices.”
- It includes a call to action. The recipient is then prompted to take some action such as click a link or respond to the email with some information. If the user clicks, they’re taken to a website that often looks like the impersonated company. It could simply prompt the user to log on with their username and password. This logon information is captured, and the user is then redirected to the actual company website, often none the wiser. If the request is for information, it often asks for the username and password, but may ask for other information such as a birthdate or address.
- It includes ominous consequences for inaction. Sometimes phishing emails impersonating financial institutions indicate that money will be lost or accounts will be frozen. If someone is doing business with PayPal or eBay, this can generate immediate concern and be enough to push someone to action.
Don’t Click That Link
Phishing emails that include links are much more common than simple requests for information. If the user does click the link, one of several scenarios occurs—and none of them are good.
The worst-case scenario is that the website automatically downloads and installs malicious software (malware) on the user’s system without any further interaction from the user. This is also known as a driveby download. This download could be malware that joins the computer to a botnet as a zombie. From here on, the user’s system does the bidding of a criminal managing the botnet’s command and control center. Some secure systems will prevent a driveby download, especially if the user is not logged on with administrator or root permissions, but some driveby downloads are still successful. Even if the driveby download is successful, the user may still be prompted to provide their credentials, or other personal information as mentioned earlier.
Users may look at the URL to see if it matches the impersonated company but the URL can be misleading. For example, the URL may be http://www.paypal.hacker.net. If the email and website looks like PayPal’s with the same graphics, a user may glance at the URL, see “PayPal,” and assume everything is OK. However, the actual site is hacker.net.
One other common tactic is to trick the user into installing a Trojan horse by prompting users with a problem. For example, users may be informed that they don’t have the correct version of software installed so that they can’t see the page can’t be displayed, or a file can’t be opened. They would then be prompted to update to a new version of Flash Player, Media Player, Adobe Reader, or something else. If the user bites, they won’t be downloading and installing an update to a legitimate application. Instead, they’ll be installing malware on their system. Of course, this is a classic Trojan horse— a download looks like it’s something useful—but it’ actually malicious.
Beware of Shortened Links
As users become educated, attackers adapt. Originally, attackers simply placed a link directly to the malicious website since users just clicked without examining the URL. As users became suspicious of sites with foreign names, attackers modified the link. For example, an attacker may have displayed http://www.pearson.com, but actually had an embedded link taking the user to the attacker’s website. Today, many users know that you can simply hover over the link and a tooltip or other display will identify the actual destination.
A newer technique is to use shortened URLs. Sites like http://bit.ly and http://tinyurl.com can take a long URL and make it short. For example: http://www.pearsonitcertification.com/promotions/promotion.aspx?promo=137954 can be shortened to http://bit.ly/djT7m9. This is especially useful in tweets limited to only 140 characters. However, you can’t tell where a link like http://bit.ly/hoLB55 will take you. A phishing email could say it’ll take you to http://www.pearsonitcertification.com/promotions, but it could just as easily take you to a malicious website.
Thankfully, you can check out the actual destination of these shortened URLs with sites like longurl.org. Enter the shortened URL into longurl.org, and it will let you know the actual destination.
Phishing Email Format
While it’s common for phishing emails to try and get users to click a link, some simply ask a user to reply with information. For example, I recently received the following phishing email which includes the common characteristics of a phishing email. It’s an actual cut and paste, including all the obvious typos and problems with English grammar.
Due to the high number of emails that have caused problems by violating our email policy, terms, and conditions, we are verifying each email account in our database.
Provide us with the below info:
Username:
Password:
Birth date:
Account owners that refuse to verify his or her account after 3-4 working days of this notification will lose account permanently from our site.
© 1998-2011
Cox Communications, Inc.
While the English and grammar has some problems, the email does have the classic characteristics of a phishing email. It’s impersonating Cox Communications, Inc. and presenting a problem in the first paragraph of many emails violating a policy. It includes a call to action, prompting the user to respond with their username, password, and birthdate. Last, it includes ominous consequences of losing their account permanently if the user chooses not to act.
On the surface, you may think that no one will answer this email and provide this information. However, I continue to get these types of emails about once a week. Why? I can only conclude that they’re working. Some people don’t recognize them as malicious. If the email is sent out to 10,000 addresses, only a few recipients need to respond to make it useful. Attackers can hijack these accounts and use them for other types of attacks.
Phishing Variants
There are several variants of phishing emails that you may come across:
- Spear phishing—This targets people within a specific organization. For example, a spear phishing email can target Bank of America by sending an email to as many Bank of America employees as possible. Spear phishing emails usually spoof the From address so that the email looks like it’s coming from an in-house address.
- Whaling—This targets a specific high-level person, such as a CEO, President, Vice President, or other executive. It will often include words such as Past Due, Legal Action, or Lawsuit in the Subject line to get the executive’s attention. If the whale bites, the potential payout for the attacker can be huge.
- Vishing—This uses Voice over IP or other voice telephone methods. The user is prompted to call a phone number perhaps through an email, a text message, or even a phone message. When the user calls, an automated message responds. The caller is notified of some problem and then prompted to enter information such as credit card numbers, social security numbers, or other information.
- Smishing—This uses SMS messages (such as those used with mobile phones) to send phishing emails. It often includes phone numbers and combines the smishing attack with a vishing attack.