They say a recent case in North Wales saw the victim engage with a person purporting to be caring for their grandson.
The victim was targeted as a result of the personal information they had made public on Facebook.
Detective Sgt Peter Jarvis of North Wales Police said: “These unscrupulous people are experts at gaining the confidence of elderly victims, encouraging them, and once trust and a relationship has been established, the thieves are quick to steal the victim's money and disappear.
“Social media sites are great fun and offer a really easy way to share information and keep in touch with friends and family. However, this information could be used by criminals for a number of reasons, including identity theft or hacking.
“Remember, you're sharing in the public domain so always consider what impact a piece of personal information might have.”
North Wales Police Cyber Crime Team are urging people to protect themselves online.
- Make sure that you know exactly what you're sharing and who you're sharing it with.
- Most social networking sites have simple settings that allow you to have complete control of who sees what. Facebook's Help Centre provides comprehensive advice on privacy and security on their site.
- Never upload or say anything in social media that you don't want the world to know.
- Always remember that sites like Twitter, Tumblr and Instagram are predominantly public spaces.
- Always log off after use.
- Don’t leave yourself logged in, this is a common mistake by many.