Happier Holidays as Ad Threat Declines

Security firm DEVCON has issued its 2019 Holiday Threat Reportwhich looks at the online scene occurring this year between Thanksgiving and Cyber Monday.

The report finds that the number of ad-threat JavaScript attacks in the US diminished year-over-year, but what attacks there were increased in sophistication. DEVCON uses the term "Ad Threat" to define a type of 3rd Party JavaScript exploitation that was in the advertising space and to separate it from the more general industry problem -- ad fraud.

Every third-party service that offers animated graphics, photo slideshows, chat bots, or shopping carts creates new vulnerabilities for the organizations that use them with the embedding of JavaScript.

DEVCON found that, “a dramatic decline in the volume of many simplistic ad hacks over the last year. Less advanced hackers are being shut out of the ad threat game, but the more advanced bad actors are not only becoming more stealthy in obfuscating these attacks, they have escalated the types of exploits, broadened the attack surface and they are not limiting these attacks to the ad tag scripts.”

So, what does “3rd Party JavaScript” do for an attacker? One route it enables is that bad actors are creating fake accounts with ad networks and using that company's ad tags to deliver exploits onto sites without ever needing to compromise the target company's servers.

Partner exploitation can happen when the attacker looks for third-party partners on checkout or payment pages and finds one that is easily compromised. That code is then used to gain access and collect user data as users are entering it.

Of course, an attacker can use any inherent vulnerabilities in the JavaScript itself (or the libraries that it uses) to carry out their attack.

Also, in the case of infected assets like image files, fonts or ads, JavaScript that is being delivered back and forth can be used to hide exploits. An image for an ad that has been infected with malicious script would be an example of this.

The report says that 2019 has seen malvertisers switch from almost entirely targeting mobile devices to the majority targeting desktop browsers. The desktop exploits are usually far more devastating to the victim when successful than the mobile redirects since they deliver a much more capable and malicious payload like a trojan.

Over 60% of the activity DEVCON observed over the shopping holiday came from variants of the Led Zelpdesk, Lucky Star, Avid Diva and Invisible Ink attacks. These attacks use a combination of social engineering and exploited JavaScript to steal a user's credit card information, have them download a trojan, or both.

It has been a continuing trend that malvertising activity has been down year over year. The report found .07% of ads over this time period contained malicious code in 2019, as opposed to 1.25% in 2018. There is no clear indicator of why this holiday shopping season saw so relatively few bad ads, but there are several factors that could contribute.

The report thinks that the security of the ad ecosystem may be influenced by market-based factors. If ad networks raise the standards for admitting buyers into their system, malvertisers will find it more difficult to sneak in.

It may be that the increased attention to the problem and adoption of security tools could also be dissuading cybercriminals who have previously experienced easier environments for cybercrime in this time period.

— Larry Loeb has written for many of the last century's major "dead tree" computer magazines, having been, among other things, a consulting editor for BYTE magazine and senior editor for the launch of WebWeek.