Warning!

Keep your guard up.

The Better Business Bureau says there's a new string of phishing e-mails making the rounds this holiday season.

Hackers and scammers are pretending to be customer service personnel from some of the biggest names in business-including FedEx, UPS, and Wal-Mart. Hackers are impersonating well-known companies that do a lot of business this time of year-specifically retailers and shipping companies-in order to quickly earn recipients' trust and gain access to computer drives, files and accounts to steal personal information such as Social Security, bank or credit card numbers.

Following are three phishing e-mails the BBB has spotted, and that con artists are relying on this holiday season to take advantage of you:

Shipping

Hackers have created phishing e-mails which pretend to be from shipping companies claiming that there is a problem with delivery of merchandise. Commonly, the e-mail will include a hyperlink for recipients to click that will take them to another Web site that might install malware or solicit personal information. A message currently making the rounds has a subject line that looks like, "Subject: Tracking Number 13040065504." The body of the message claims that a package couldn't be delivered and advises the recipient, "To take your package back you should print the copy of invoice that is in the added file." Of course, the attachment is actually a virus that will infect the computer if opened.

BBB ADVICE: Instead of clicking on the link in the e-mail, go directly to the shipper's Web site or contact the company via phone in order to confirm whether there is a shipping problem with your package. Do not open attachments to unsolicited e-mails.

Surveys Offering Holiday Spending Cash

In an effort to take advantage of cash-strapped holiday shoppers, phishing e-mails are circulating pretending to be from retailers such as Wal-Mart. One e-mail has a subject line that reads, "Online Survey from Wal-Mart Stores!!!" And the body of the message states, "This survey has been sent only to a few people from our random generator!", and "You've been selected to take part in our quick and easy 9 questions survey. In return we will credit $90.00 to your account - Just for your time!" Ultimately, the e-mail includes a link to a Web site where the recipient is supposed to take the survey, but in fact leads to a phishing site.

BBB ADVICE: Do not respond to unsolicited e-mails that promise money for answering surveys. Spam e-mails that offer big rewards with little effort will almost invariably cost you in the end.