The number sequence '123456' has topped a list of the 25 most commonly used passwords.
The rundown was compiled from files containing millions of stolen passwords posted online last year following a major security breach at software company Adobe in October, which affected tens of millions of users.
The word 'password', which previously held the top spot in the rankings, slipped to number two on the list according to the author of the research SplashData, which makes password management applications.
Chief executive Morgan Slain said: "Seeing passwords like 'adobe123' and 'photoshop' on this list offers a good reminder not to base your password on the name of the website or application you are accessing."
The company said the list showed that "many people continue to put themselves at risk by using weak, easily guessable passwords". Other passwords in the top 10 included 'qwerty' – six adjacent letters on a computer keyboard – 'abc123', '111111', and 'iloveyou'.
Slain added: "Another interesting aspect of this year's list is that more short numerical passwords showed up even though websites are starting to enforce stronger password policies. For example, new to this year's list are simple and easily guessable passwords like '1234' at number 16, '12345' at number 20, and '000000' at number 25.
"As always, we hope that with more publicity about how risky it is to use weak passwords, more people will start taking simple steps to protect themselves by using stronger passwords and using different passwords for different websites."
SplashData has advised consumers or businesses using any of the passwords on the list to change them immediately.
The company warned that even passwords with common substitutions such as 'dr4mat1c' can be vulnerable to attackers' increasingly sophisticated technology and they also suggest that random words should be used for passwords rather than common phrases, and that web users should avoid using the same username and password combination for multiple websites.
The top 25 most commonly used passwords of 2013 are: