My mac keeps automatically downloading weird files

Question

every 30 seconds or so my mac will download files with extension names like 73982ad.html and other 5 digit number combos followed by "ad". Is this a virus? How do I make it stop? I delete the files as soon as I see them, but I'm worried it's something bigger.

Answer 1

Both of those sites are on a list of known malware distributors.  They are extremely untrustworthy sites.  However, that does not necessarily mean that there is malware involved.
Do these files continue to appear when you don't have any web browser open?  If yes, there's some other software downloading them, which could be (but is not necessarily) malware.
If no, do those files start appearing as soon as you open a web browser?  Or do they only start appearing after you have visited a particular site?
Also, note that your e-mail account could be hacked without malware being involved.  That often happens with accounts on popular servers (Yahoo, Hotmail, GMail, etc) when you have a very weak account password.
To rule out malware in all these cases, just download a copy of ClamXav and run a scan of your entire hard drive.  (Note that ClamXav is the only AV software I recommend on a Mac.)  For more information about Mac malware, see my Mac Virus Guide*.
* Disclaimer: links to my pages may give me compensation, and should not be taken as endorsement of my services by Apple.