Gmail users: Watch for sophisticated scam

An email announcing an opening in a charter school for Heather Davis-Jones' daughter Shakia is pictured at their residence in Philadelphia, Pennsylvania February 9, 2013. REUTERS/Tim Shaffer/Files

A devious new scam targeting Gmail users shows you can't trust that any e-mail is safe, even if it comes from someone you know and appears to be part of an ongoing conversation. 

Cybercriminals are hacking Gmail accounts and using the e-mail chains they find there to send personalised scam messages to people the account holder previously corresponded with. The e-mails use the same subject lines and file attachment names that were used on previous email exchanges, making them appear legitimate.