Originally Posted by tmc8295
Forums are really no more or less dangerous than any other website online, it does depend on the people and type of forum a little of course but in general you wont have a problem if you are smart and careful, just like with any toher website on the internet.
-Certified Computer Technician
In general I would agree, particularly with the point about being smart and careful (better than any AV/security software that will ever exist), however I would also note that one things forums (like blogs) make heavy use of is off-the-shelf software utilities such as phpBB, wordpress, joomla, drupal etc.
These software packages are popular targets for vulnerability research as a successful exploit can affect a huge number of websites, which - by definition in the case of forums - hold a lot of user account credentials for harvesting. If the site also makes use of some e-commerce cart software (such as OpenCart) then this adds payment details into the potential 'rewards' and hence further incentivises any potential attacker.
Without wanting to change the subject of this thread, this is also why such a pronounced reaction has taken place as a result of heartbleed - because OpenSSL is such a core technology.
Much like economics it is supply and demand: Windows > Mac > Linux exploits, not because any one of them is less secure (ignoring third-party software) but because there is more potential victims to target.