The volume of malicious adverts soared a staggering 260% in the first half of 2015, compared to the same time last year, according to new data from security vendor RiskIQ.
The firm claims to analyse around two billion publisher pages and 10 million mobile apps each day, adding weight to its findings.
It logged 250,000 malicious ads in the first six months of 2014 – a number which rose to 450,000 by the same period a year later.
When it comes to unique malvertisements, the figure rose 60% over the period – from 50,000 to 80,000.
The firm said that the automated nature of the industry leaves gaps for cyber-criminals to exploit – hiding malicious code inside ads or embedding executables within web pages, for example.
“The major increase we have seen in the number of malvertisements over the past 48 months confirms that digital ads have become the preferred method for distributing malware,” said RiskIQ research director, James Pleger, in a statement.
“There are a number of reasons for this development, including the fact that malvertisements are difficult to detect and take down since they are delivered through ad networks and are not resident on websites. They also allow attackers to exploit the powerful profiling capabilities of these networks to precisely target specific populations of users.”
It claimed fake Flash updates are the most common lure used by cyber-criminals to trick users into downloading malware in 2015, overtaking fake AV and Java updates.
Also this year, fake software updates have become the most popular method for installing malware, surpassing exploit kits.
Just this week Malwarebytes revealed a new malvertising campaign targeting Yahoo sites. Although the web giant acted quickly to shut down the attack, it briefly gave the group behind it access to the firm’s 6.9 billion monthly users.
Victims were exposed to the Angler Exploit Kit, which has been used in the past in such campaigns to deliver CryptoWall ransomware or effect click fraud.