Berlin: Computer experts from Germany have warned people to be more careful while surfing the internet as malicious programs called "drive-by downloads" can be downloaded unintentionally when users visit "manipulated websites".
Currently the biggest threat was the so-called "drive-by downloads", according to the German Federal Association for Information Technology, Telecommunications and New Media or Bitkom.
"Cyber criminals are operating in increasingly sophisticated ways," said Bitkom president Dieter Kempf.
"Drive-by downloads" are particularly insidious because they are hard to recognise.
Just a visit to a manipulated website is sufficient to make a personal computer vulnerable to attack.
Other important items in a list of internet threats are so-called worms and Trojans, followed by attacks on databases and web applications.
The Hasso Plattner Institute for Software Systems Engineering (HPI) called on internet users to be more careful in their choice of passwords.
Almost one in three people choose a sequence of six or fewer characters.
Short and simple words are also popular, criticised HPI Director Christoph Meinel.
However, these fall far short of providing secure access protection.
Around half of internet users also have the same or a similar password for multiple pages.
The HPI recommends a combination of uppercase and lowercase letters, numbers and special characters.
Terms that are in the dictionary, as well as names and dates of birth, should be avoided.