Researchers at Malwarebytes spotted a malvertising campaign that abused Google Ads to target people searching for Google Authenticator.
If someone typed “Google Authenticator” into Google, the malicious ad would be at the top of the search results. The ad copied the website description from the real Google Authenticator, but would redirect users to a phishing site.
“We can follow what happens when you click on the ad by monitoring web traffic,” the researchers explain. “We see a number of redirects via intermediary domains controlled by the attacker, before landing on a fake site for Authenticator.”
If a user clicks the download button, the site will install the DeerStealer malware. The researchers note that the malicious file is hosted on GitHub, making it more likely to bypass security tools.
“Hosting the file on GitHub allows the threat actor to use a trusted cloud resource, unlikely to be blocked via conventional means,” the researchers write. “While GitHub is the de facto software repository, not all applications or scripts hosted on it are legitimate.”
Malwarebytes concludes that users should be aware of this tactic so they can avoid falling for these attacks.
“Threat actors have been abusing Google ads as a way to trick users into visiting phishing and malware sites,” Malwarebytes says. “Since the whole premise of these attacks relies on social engineering, it is absolutely critical to properly distinguish real advertisers from fake ones. As we saw in this case, some unknown individual was able to impersonate Google and successfully push malware disguised as a branded Google product as well.
We should note that Google Authenticator is a well-known and trusted multi-factor authentication tool, so there is some irony in potential victims getting compromised while trying to improve their security posture. We recommend avoiding clicking on ads to download any kind of software and instead visiting the official repositories directly.”
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