On Facebook and Instagram, there are lottery scams, celebrity impostors and even fake Mark Zuckerbergs . There is also a scheme where scammers pose as American service members to cheat vulnerable women out of their savings.

Here are five things to know about it.

How does it work?

Scammers steal photos from service members’ Facebook and Instagram profiles and use them to create impostor accounts. To find victims, they search Facebook groups for targets — often single women and widows — and then message hundreds, hoping to hook a few.

Once they have a potential mark, the scammers shift the conversations with their victims to Google Hangouts or WhatsApp, messaging services owned by Google and Facebook, in case Facebook deletes their accounts.

For months or weeks, they try to seduce the women with sweet talk and promises of a future together. Eventually, they ask for money. When victims send funds, they often do so via wire transfers or iTunes and Amazon gift cards, which the scammers sell at a discount on the black market.

How have internet scams changed with Facebook?

Internet scammers arrived with the dial-up modem years ago, conning people in chat rooms and email inboxes. Now Facebook and Instagram provide fraudsters with greater reach and resources, enabling them to more convincingly impersonate others and more precisely target victims.