Online advertising is big business. Virus writers attack ads that are delivered to popular and safe websites, replacing good ads with malware, viruses and other infections. Since malware is delivered at a presumed safe website, the poisoned ads can be very effective and widespread.
Here are some examples:
MSN Home Page Spreads Malware Via Malicious Ad – GrahamCluley.com (2016)
Malware strikes thousands of Yahoo users via poisoned adverts – GrahamCluley.com (2014)
Poisoned Ad Problems on Forbes – Sophos.com (2016)
Is it time for an anti-virus change?
Keep your anti-virus program updated to the latest version. If you’re using a free anti-virus and it allows infections, consider that the free version may not be enough to protect you and either purchase a higher level of protection or change anti-virus programs to something more effective. A helpful list of anti-virus software and providers.
Add anti-malware protection.
Supplement your anti-virus program with active anti-malware protection. Example Malwarebytes Premium.
This option is highly recommended. A client of ours didn’t have this option. An employee was surfing online at a trusted website which had an infected advertisement. The infection installed a virus that scrambled thousands of PDF documents and held them for ransom for hard cash. Please consider supplimenting your anti-virus protection with anti-malware protection.
Get all-in-one protection.
Change to an all-in-one solution that includes active anti-virus and active anti-malware protection. Example Emsisoft Anti-Virus Anti-Malware.
Block online ads.
Use an online ad blocker. Not seeing the ads will prevent any poisoned ads from displaying on your computer.
Out of the above options, we recommend to our customers anti-malware protection (#2 above). We also recommend an all-in-one solution (#3 above) and using an online ad blocker (#4 above).