Businesses are being targeted in a malvertising campaign that uses Google Ads that impersonate the Webex download portal and trick them into downloading an installer for the video conferencing platform that delivers BatLoader malware.
BatLoader is a type of malware used for gaining initial access to networks and it is often delivered via malvertising campaigns bundled inside Microsoft Software Installation (MSI) packages. The sites used to distribute the malware often use search engine poisoning (SEO) techniques to get web pages to appear high up in the search engine listings for search terms likely to be used by employees. Threat groups previously known to use BatLoader for initial access have used it to download malware variants such as QakBot, RacoonStealer, Bumbleloader, Cobalt Strike, and the Arkey information stealer. Infection with BatLoader can easily lead to data theft and ransomware attacks.
BatLoader is evasive, and the threat actors behind BatLoader campaigns use living-of-the-land techniques once initial access has been gained which can make detection of malicious activity difficult in the early stages of the infection chain.
One of the latest campaigns is a departure from the standard method of delivery as Google Ads are being used rather than SEO poisoning and the campaign stands out from other malvertising campaigns as the malicious adverts are indistinguishable from the genuine advertisements for Webex software.
The easiest red flag to identify in malvertising campaigns is the website offering the software download is not the official site used by the company being impersonated. This campaign, however, displays the correct Webex logo and the legitimate Webex.com URL in the Google Ad, and the adverts appear in position 1 at the top of the page. If the URL is clicked, however, the user will be redirected to a malicious website.
Checks are performed when the ad is clicked in an attempt to filter out automated crawlers and researchers using sandboxes. If the user is rejected, they will be directed to the official Webex site. If the checks are passed, they will be directed to the webexadvertisingoffer[.]com site where they will be offered a fake Webex MSI installer. In this campaign, BatLoader will be delivered along with the DanaBot banking Trojan. DanaBot is capable of stealing passwords, taking screenshots, providing direct access to compromised hosts, and is often used to download ransomware.
The threat actors are able to create legitimate-looking Webex ads by exploiting a loophole in the Google Ads platform using tracking templates. Rather than use a specific URL in the ad for all clicks, tracking templates allow the advertiser to specify the URL for the redirect based on user parameters, such as the device type, location, and other information.
While Google’s policy is that the display URL and the final URL must be on the same domain, the tracking template may redirect users to a different website. In this case, a Firebase URL is used for the tracking template which has a final URL of webex.com, but clicking the ad directs the user to a different URL at monoo3at[.]com where filtering takes place and users are either directed to the malicious download page or the official Webex site, depending on the fingerprinting that occurs at monoo3at[.]com.
A web filter offers protection against malvertising by blocking access to known malicious websites such as the domain used in this campaign, restricting web activity to administrator-defined websites through category filtering, and blocking downloads of executable files. Administrators often block downloads of MSI files to protect against malware and to curb the installation of unauthorized software (shadow IT).
Security awareness training should also teach employees not to download files from unofficial websites. While the advert in this case is indistinguishable from the genuine site, the site offering the malicious installation package is not the official vendor site and the download can therefore be avoided.
TitanHQ can help businesses defend against malvertising through a combination of the WebTitan web filter and the SafeTitan security awareness training platform. Both solutions are available in a free trial, and product demonstrations can be arranged by calling the sales team.