Domains once used in card-skimming attacks launched by threat actors under the Magecart umbrella are being repurposed for new ad fraud campaigns, researchers say.
Magecart, once a term attributed to a single threat group, now encompasses multiple attackers using the same kinds of tactics to compromise online merchants and services which use payment portals.
Countless US campus stores have also fallen victim to Magecart attacks, and in recent months, Magecart attackers have also used "spray and pray" tactics to compromise thousands of websites by focusing on vulnerable S3 buckets.
As Magecart attacks are detected, the domains facilitating the transfer of stolen data and the domains used as repositories for malicious code are reported, sinkholed, and seized.
However, according to RiskIQ, these malicious domains are eventually released back into the pool of available domains -- and many are being snapped up for new attack varieties by fraudsters.
On Thursday, cybersecurity researchers said that when the Magecart domains appear back online, "they retain their call-outs to malicious domains placed on breached websites by attackers, which means they also retain their value to threat actors."
In other words, domains previously connected to campaigns can be re-purchased to resurrect old attacks or for use in new schemes -- such as the generation of income through malvertising and ad fraud.
Malvertising is the compromise of ad networks and space on legitimate domains to deploy malware or redirect victims to malicious websites. The term can also be used to describe fraudulent ways to make money from ad networks, such as the infection of systems to force users to watch ads or to unwittingly provide traffic to advert pages, thereby generating illicit income for fraudsters.
RiskIQ says that some old Magecart domains are being used for these purposes.
Once in the fraudster's control, the exact call once used to grab skimmer code was now set to work for use in monetization. Instead of reloading the path with information-stealing malicious code, the new owners injected an advertisement page instead.
Counters along these paths have also been spotted, which suggests the owners of the old Magecart domain have done this more than once and want to measure the size of their fraudulent ad audience.
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The so-called advertising secondary market for old Magecart domains might not be facilitating the fresh deployment of malware at present to revitalize old card-skimming campaigns, but the use of previous Magecart domains for ad space due to the traffic coming back to them is still fraudulent.
"While ads themselves aren't malicious, they are exploiting the vulnerabilities in websites while the site owners don't benefit," the researchers say. "Moreover, in the future, threat actors may also engage in other schemes and threat activity far more malicious than advertising."
RiskIQ says that it is not possible to keep a website "clean forever," but with Magecart attacks becoming such a prevalent threat over the past few years, "dutiful vigilance and maintenance" is the only way to prevent follow-up schemes prompted by the secondary market for old malicious domains.
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