Flagged as "Malware" due to external images
 

Recently the users of our site experienced warnings while visiting some threads, saying that it contained harmful elements.

The research of the case indicated that some users posted pictures hosted in other sites, which were compromised. Due to that, our site was being affected because of the use of resources in those compromised sites. Of course we removed the images.

One option is to host the images attached on the posts ourselves, but this clearly would produce a huge database increase (this forum has a high content of images).

Has anyone had to deal with this situation?
Are there any advices on how to prevent this?

Starters, set vb to store images in the file system, not the db.

You can also censor the compromised sites in question used in the past via the admincp word sensor options.