Malvertising — the practice of using legitimate ad banners and links as malware carriers — has become a standard practice for many cybercriminal groups. However, companies are now taking steps to remedy this situation. As reported by The Hacker News, most of Google Ad Services traffic will be encrypted by June 30. However, will this focus on security drive out malvertising or just send it deeper underground?

Marketing Nightmare

Digital ads represent huge revenue potential for companies and providers alike, but the large-scale audience of these ads makes them tempting targets. As noted by eWEEK, for example, a malware producer recently pushed a fake advertisement through a legitimate ad network, where it was served across networks such as Merchenta and Google’s DoubleClick. The malicious ad made its way through by first creating a version free of any malware used to pass network security checks. Just before the ad was set to go live, a minor update was applied that contained the malware package. The result? Even viewing the ad resulted in the download of a CryptoWall-type malware, an elevated form of typical click-to-infect offerings.

According to PCWorld, a Google partner in Bulgaria was also hit with large-scale advertising malware. Dutch security firm Fox-IT found that ads coming from Engage Lab were redirecting users to the Nuclear Exploit Kit, which targets Adobe Flash Player, Oracle Java and Microsoft Silverlight. While the redirects stopped within a day of the problem being discovered, Fox-IT reported there were “a relatively large amount of infections and infection attempts from this exploit kit among our customers.” Recent attacks make it clear that Google’s large ad space puts it under the gun when it comes to malvertising. Its answer? Encryption.

Lock It Down

Since 2008, Google has championed a switch to all HTTPS. The search giant already encrypts Gmail data moving between internal servers on Google Search and gives priority to encrypted websites in search results. However, Google Ad Services has been slower to follow suit due in large measure to the sheer reach and complexity of the platform. In the wake of recent attacks, however, the company is taking steps to encrypt the vast majority of ad traffic by June 30 and give all advertisers using Google buying platforms the ability to serve HTTPS-encrypted display ads to all HTTPS-enabled inventory. In other words, this won’t be a mandatory switch, but it will operate at the discretion of individual advertisers.

Will this stop malvertising? Not entirely. A significant reduction of man-in-the-middle attacks is expected, but there will likely be a rise in more sophisticated malware that hides behind encrypted services and is more difficult for security researchers to pinpoint. As noted by CIO, cybercriminals often leverage encryption for their own purposes since many companies don’t inspect Secure Socket Layer traffic owing to high bandwidth requirements. If cybercriminals can push ads out through their own networks and onto Google-enabled platforms, users may be less discerning about what they click on due to the secure-seeming presence of an HTTPS designator.

Ultimately, Google Ad Services moving to near-total encryption is a good thing both for the search giant and advertisers who don’t want their name inadvertently associated with malware. For IT security professionals, however, the rise of encryption simply weeds out low-level attackers and sets the stage for more sophisticated threat vectors. Simply put, there is always a market for malware.

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