NEWS: How Malvertisers are Exploiting Google Ads

October 25, 2023

A malvertising campaign that manipulates Google Ads to divert users seeking popular software to fraudulent landing pages and deliver subsequent-stage payloads has come to light. Malwarebytes, the firm that unearthed this activity, described it as “distinctive in its methodology of fingerprinting users and distributing time-sensitive payloads.”

This attack specifically targets users looking for Notepad++ and PDF converters to display counterfeit ads on Google’s search results page. When these ads are clicked, the system weeds out bots and other unintended IP addresses by presenting a decoy website. If the visitor is considered valuable to the threat actor, they are rerouted to a cloned website promoting the software, while the system quietly fingerprints the system to ascertain if the request is coming from a virtual machine.

The Intricacies of the Malvertising Campaign

Users who fail the verification are directed to the official Notepad++ website, while a potential target is given a unique ID for “tracking purposes and also to make each download unique and time-sensitive.” The terminal-stage malware is an HTA payload that establishes a connection to a remote domain (“mybigeye[.]icu”) on a custom port and delivers subsequent malware.

The Director of Threat Intelligence, stated, “Threat actors are successfully employing evasion strategies that circumvent ad verification checks and enable them to target specific victim types.” He added, “With a dependable malware delivery chain at their disposal, malicious actors can concentrate on enhancing their decoy pages and creating custom malware payloads.”

Overlap with Similar Campaigns and the Use of Punycode

This revelation coincides with a similar campaign that targets users searching for the KeePass password manager with harmful ads that direct victims to a domain using Punycode (keepass[.]info vs. ń∑eepass[.]info), a unique encoding used to convert Unicode characters to ASCII.

The Role of Decoy Sites and Malicious Installers

Users who arrive at the decoy site are duped into downloading a malicious installer that ultimately triggers the execution of FakeBat (also known as EugenLoader), a loader designed to download other malicious code.

The misuse of Punycode is not entirely new, but its combination with rogue Google Ads indicates that malvertising via search engines is becoming increasingly sophisticated. The objective is to execute a homograph attack and entice victims into installing malware by using Punycode to register domain names similar to a legitimate site.

The Constant Evolution of Threats

Multiple threat actors such as TA569 (also known as SocGholish), RogueRaticate (FakeSG), ZPHP (SmartApeSG), ClearFake, and EtherHiding have been noticed exploiting themes related to fake browser updates to disseminate Cobalt Strike, loaders, stealers, and remote access trojans, indicating that these attacks are a persistent, evolving threat.

Researchers stated in an analysis published this week, “Fake browser updates exploit end user trust with compromised websites and a lure customized to the user’s browser to legitimize the update and fool users into clicking.” He warned, “The threat is only in the browser and can be initiated by a click from a legitimate and expected email, social media site, search engine query, or even just navigating to the compromised site.”