Victims of the scams have been duped into giving away information or clicking on a dangerous link by cyber criminals claiming to be their friend.
The scam, mainly being circulated on Facebook, tells people they have won a competition such as the Postcode Lottery or a Facebook competition.
South Yorkshire Police is asking people to stay alert to these risks following a number of reports.
Cyber Protect Officer Dannielle Lee said: "We all know that social media is a brilliant way to stay in touch with friends. It was particularly important to many of us during lockdown, and now we're able to get out again many of us are using platforms to share photos and updates of our reunions and celebrations.
"Unfortunately, cyber criminals are lurking on these sites too. Hackers can access accounts and then pose as someone you trust to trick you into giving away your personal details.
"In recent cases, mainly on Facebook, South Yorkshire victims have been told that they have won the Postcode Lottery or a Facebook competition. Their 'friend' has asked for their details and encouraged them to click on a link which is unsafe.
"As part of the scam, the hackers are also then able to take over the victim's account and will go on to target their friends too."
Anyone who has been a victim of cyber crime or fraud can report it to Action Fraud at www.actionfraud.police.uk or by calling 0300 123 2040.