Christmas can be a rip-off.

Bloomberg reports that Internet sales are expected to increase 17 percent from 2011, and all that online commerce brings the scammers out to play, according to the Better Business Bureau’s Erin Dufner.

Many of these grift-givers attack via email, she says. Their goal is to trick you into clicking on links that will download malware or infect your computer with a virus. This malicious code might be able to pick up personal information stored on your computer.

If you keep your usernames and passwords in a Word or text file, for example, the malware might gain access to them. Cookies — bits of code stored on your computer whenever you grant a website permission to save your username and password so that you won’t have to enter it the next time you log in — are also vulnerable.

So are senior citizens, especially if they are not Internet savvy. "They tend to reply via mail and provide personal information," Dufner says.

Red flags for Internet scams include messages that have a return email address from a different country, include order verifications from places where you did not place an order, or appear to be from banking institutions, perhaps claiming that you’ve reached your credit card limit or have bounced a check. These types of bogus emails will often request confirmation of usernames, passwords or personal information.

The BBB recommends that consumers not click on links in email messages that appear to be from financial institutions. Instead, open a new browser window, head to your bank’s site and log in there. Beware of any email that asks you to verify your credit card information.

"If you do get something that looks fishy, reach out to your financial institution," Dufner says, adding that a lot of banks and credit card companies provide live, online chat that allows you to connect instantly with an employee. Another option is to call them and report the suspicious mail.

Dufner encourages consumers to look at credit card and banking statements more frequently over the holidays. Checking your bank and credit card statements every couple of days online can help you manage your finances during the holidays, and if you notice a suspicious transaction, you can have it checked out in a timely fashion.

To safeguard against viruses and malware, use virus protection software and make sure that it’s updated. As far as passwords go, keep them long and hard to guess, and use a different password for each site you visit that requires one. "It can be difficult to remember a lot of passwords, but we have to keep safe," Dufner says. This is especially important because many sites now require you to use your email address as a username — that’s one less piece of information the scammers need to discover.

Don’t store your passwords electronically, Dufner advises. Instead, keep them in a home safe or another secure location. If you do store them on an electronic device, make sure that it’s locked, secured and password-protected itself.

Job and charity scams

Another scam that increases in frequency during the holidays is often perpetrated online by parties offering seasonal jobs. "They can extend past the holidays because people are looking for extra cash to pay off credit cards and holiday purchases," Dufner says.

Watch out for companies asking you to give them money up front; that should get your scam detector flashing. Solicitations that promise you can work from home and guarantee you will earn big dollars per month or per week are also suspect. "Any kind of job offer that sounds too good to be true is definitely a red flag," Dufner says.

Be wary of offers for overseas jobs that arrive out of the blue or ask you to fill out an application online requiring sensitive information. "Legitimate employers will probably ask to see you in person," Dufner explains.

Holiday scams aren’t confined to the Internet. Most egregiously, charity scams increase during the season of giving. Perpetrators might call on the phone claiming to be from an organization with a legitimate-sounding name. They might also boldly knock on your door, dressed up in a familiar or official-looking outfit. Maybe they’re pretending to collect for a church.

"Do research as a consumer," Dufner advises. Go to BBB.org as well as Give.org — a Better Business Bureau site which provides reports on charities nationwide. And ask questions of anyone asking for your money. "A legitimate charity will take your money tomorrow as well as today," she says. "Take the marketing materials, do your research and contact them later." Don’t just send a check, and never give cash.

Finally, never give out personal information to anybody that you don’t know — especially financial information.