Cyber criminals are scraping personal information from thousands of Australians' social media profiles and using it to trap victims with ransomware — a type of malware that freezes computer files and demands money to unlock them.

The ransomware — appropriately titled 'Locky' — is spreading quickly round the web in various guises, but security experts have found it in yet another AustraliaPost email scam.

Hackers are using Australia Post and personal information gleaned from social media to scam victims. Credit:Jessica Shapiro

What makes the scam so dangerous is that it addresses the recipient with personal information such as their full name, location, workplace and job description — all gleaned from their social media profile and designed to dupe them into thinking the email is legitimate.

MailGuard, the anti-virus and security company which discovered the scam, said hackers were using "highly advanced" scraping software to scan social media profiles and automatically deliver the malicious email to tens of thousands of victims.