Spear Phishing is simply as the title of this article indicates, it is the same as phishing but focused on a much smaller audience. A small net to catch just a few, or one, big fish. Often the attack is tailored to a particular individual, office or company. The bait is customized with information familiar, and specific, to the target. Often the attack takes on characteristics of a traditional con. The attacker uses information about you or your company to lower your guard and defeat any skepticism you may have that the email you just received is a scam. The information may be easily obtainable from the Internet, a phone book, or perhaps from a call to the office secretary. Social engineering is often a part of a good spear phishing attack. There is also some sort of bait to convince you that the message isn't just legitimate spam (because even if the sender of the email knows you that doesn't mean you want to open their email).

An attacker may use jargon used by the individual's business or line of work. They may express familiarity with other people within the company and mention them by name. Sometimes they'll reference procedures or forms used by the targets agency. Each of us may think we would never fall for this, but think of the people you work with. Given a personally addressed email that referenced a company specific product or service how many would open an attached file? Especially a MS Word or Excel file (both of which have had exploits recently that can be used to compromise a computer). Probably a large percentage of your coworkers would fall for this.

The goal of a spear phishing attack is often to obtain very specific information. It could be financial information, insider contract information, passwords, sensitive employee data, etc. (Studies show that a large percentage of users are still all too willing to give out their password to someone they don' know that claims to work for the IT department.) If they still fall for that they'll fall for most anything. (See References and Recommendations below)

Scenario 1:
Motivation: Wreak Havoc at a government office
Method: Combined social engineering / spear phishing attack
Details: Attacker finds an employee contact page on the Internet by searching Google for +“employee contacts” +site:gov. This turns up a number of web pages with contacts at various government offices. Attacker settles on a department at XYZ.GOV because not only do they list employee names and email addresses they also list the person's title (many offices still do this). The office also has a Homeland Security role so a successful attack would likely get lots of publicity. The attacker begins by calling a mid-level employee, John, in department YYY saying that he needed to open a trouble ticket for a virus on his computer. John has no idea why this person called his number but promptly gives the person the phone number of the IT Help Desk. Before he hangs up the attack asks John what antivirus he uses and whether he has had any problems before. Attacker then calls the help desk to open a ticket in John's name. While on the phone with the Help Desk the attacker makes friendly and gets this help desk person's name and email address. The attacker now spoofs an email from the Help Desk employee to a few select high level employees at department YYY with the addresses obtained from the web. The email from address is spoofed so that it apparently comes from the Help Desk employee. The email is very convincing as it contains a real name, real phone number for the help desk, even the help desk employee's personal telephone extension. The email also asks recipients to open the attached executable in order to install an antivirus security patch. Of course the attachment is actually a unique backdoor trojan and keylogger. The trojan will not be detectable by the departments antivirus and will install a rootkit that may never be found. After getting login information for the department head the hacker then logs in to several sensitive systems over the course of weeks and makes changes to existing data. The department head's computers are essentially owned by the hacker until they're replaced or completely rebuilt from the ground up.

Scenario 2: (currently being played out)
Motivation: Money
Method: Google harvest / spear phishing attack
Details: Attacker uses an off the shelf email address collection program to harvest email addresses of government employees. These programs are very simple to use and using spidering techniques can collect thousands of targeted email addresses per hour. Attacker uses these addresses to send phishing emails to government employees. The phishing message claims to be from Bank of America (BoA) asking people to update their BoA profile information. The message looks real, is addressed to “Dear Government Employee” and mentions their “government” BoA credit card. Over 1.2 million federal government employees have a BoA credit card and most are use to getting email messages asking them to update their information in some government system or another. Of course once they log in to the system from this email the phishers start running up charges against their government credit card. The Department of Defense specifically addresses this scam in it's spear phishing training that all DoD employees are required to take. But people are still being fooled.

Spear phishing scams are only limited by the attackers imagination. People are just much too likely to be tricked by a phishing email if it contains targeted information familiar to them. We also make it far too easy for attackers by including targeting information on websites. Web pages with information such as a person's email address, job function, title, phone number, mailing address, department name, recent projects they've worked on, client names, etc. are gold mines for the attacker. Employee locators are rich with this type of information and contain lists of thousands of people.

We recently used a government agency employee locator to find an email address of someone in IT security at that office so that we could notify them of a critical vulnerability on their website that was reported to us. When we found an address that said something like cybersecurity@domain.gov we added that as one of the addresses notified. Turned out that address was actually a mailing list. Everyone that had anything to do with IT in that agency received the email! We know because we received hundreds of return receipts. Bad idea to publish that address, in fact mail from the outside shouldn't be allowed to reach such a group (this agency promptly came to the same conclusion). But such an address is perfect spear phishing. Not only does it reach a large targeted audience but the email address even tells you what its used for. Had this been a new unpublished exploit used by an attacker it could have brought that agency down for days and caused immeasurable harm.

Recommendations:

• Training – Though it may not seem as easy as installing a security appliance at the perimeter it is still one of the most effective steps against any social engineering attack. As mentioned above the Department of Defense has mandated it for all DoD employees. Even with all the money and technical know-how they can throw at the problem this was still one of the most important steps.
  
• Block inbound message at the perimeter that contain a from address with your own domain (as applicable). Make sure mail from known sources originates from those sources. Eg; If you do a lot of business with a sister organization make sure email from that organization originates from known SMTP servers.
  
• Use digital signatures where possible. This is being mandated within DoD and will soon be used throughout the federal government. If an important email is not signed ask the sender to resend it digitally signed. Yes, this can require a large PKI infrastructure but if you are implementing PKI for authentication, HSPD-12, DoD's Common Access Cards (CAC), etc. then by all means start using them within your organization to digitally sign your email. Its the best method for verifying the sender of an email.
  
• Use encryption. If only the sender and yourself know the shared secret key then no one else will be able to impersonate one of you to the other. Of course symmetric key encryption (where the key is the same to both encrypt and decrypt a message) becomes very difficult to manage with a large number of people. But its certainly an option. Asymmetric encryption (public / private key) requires the same PKI infrastructure mentioned above or some sort of web of trust to certify the person is who they say they are (see the following description on how the product Pretty Good Privacy (PGP) works).
  
• Double up on your current spam defenses. Often times phishing messages originate from compromised computers or botnets. Your anti-spam appliance may have already identified the source as a compromised or rogue SMTP server. Having multiple devices, or services, verifying incoming mail ups the odds of detection.
  
• Make sure your users are using either IE7, Firefox 2.0, or Opera 9.1 as those web browsers include some built in protection against known phishing websites. Each of these browsers use technology to compare visited sites against databases of discovered phishing sites. None of these products will offer much protection against true spear phishing since the “narrow net” would probably involve a server that had not yet been discovered. But every layer of protection helps.

References:

• What is Spear Phishing by Microsoft
  
• Spear Phishing by Wikipedia
  
• What Is Spear Phishing from SearchSecurity.com Definitions
  
• DoD's Spear Phishing Awareness Training – Unclassified PowerPoint but hard to find if you're not part of one of the military Intranets. This link may not work for long so get it while you can, with a little modification it would be great training for any end-user.
  
• DoD Information Assurance Awareness – by Defense Information Systems Agency (DISA). Excellent end-user training that can be used by anyone. Takes about 1.5 hours to complete and includes a short test at the end.
  
• DoD Battles Spear Phishing – by Federal Computer Week. Real-life spear phishing examples of what the military faces daily. The same techniques can be used against anyone. The argument can be made that every organization or company has something they don't want falling in to the wrong hands.
  
• AntiPhishing.Org – A good source of Anti-Phishing information, news, training, whitepapers, and statistics.

Web NIST.org NIST.gov SecurityFocus.com