LastPass, an online password management provider, has said it will force its over one million users to change their master passwords.

The company has said that it is taking such a measure out of fear of a possible hacking attack after detection of a "traffic anomaly" on one of its database servers.

In a blog, LastPass said that last Tuesday it had found two "traffic anomalies," including one leaving the company’s database, which means that data theft could have taken place. The company said it could not find the cause for the glitch.

The company is forcing its users to change their passwords as a precautionary measure.

"We’re going to be paranoid and assume the worst," LastPass said.

"After delving into the anomaly we found a similar but smaller matching traffic anomaly from one of our databases in the opposite direction," the blog said.

"We also know that the amount of data taken isn’t remotely enough to have pulled many users encrypted data blob," LastPass added.