A new malware variant has appeared that is being pushed out via malicious search engine advertisements that appear at the top of the listings for searches related to cracked software. The new malware has been dubbed MosaicLoader by Bitdefender researchers, who have seen increasing numbers of the malware appear in recent weeks.
As the name suggests, MosaicLoader is a malware downloader. It has been developed to deliver a range of different payloads onto victims’ devices, with the ‘Mosaic’ part of the name coming from the intricate internal structure of the malware, which was developed to hamper attempts by security researchers to analyze and reverse engineer the malware.
The malware is complex and uses a variety of methods to evade detection and hamper attempts at analysis, including code obfuscation with the code broken into small chunks, shuffling the execution order and creating a mosaic-like structure. The malware also mimics the file information of legitimate software.
The current campaign delivering MosaicLoader targets individuals looking for cracked software, with the adverts appearing in the search engine listings for a variety of keywords and terms associated with pirated software. The initial malware droppers masquerade as executables for a legitimate software, including using company names and descriptions within the metadata and similar icons and file info as legitimate software.
The initial droppers use a variety of names linked to pirated software, including mirc-7-64-keygen-plus-crack-fully-version-free-download, officefix-professional6-122-crack-full-version-latest-2021, and setup-starter_v2.3.1. One of the droppers mimics a legitimate NVIDIA process, although the digital signature is unrelated to NVIDIA. Once users start processes with names in the word cloud of installers, the infection chain commences and will run in the background without alerting the user, with no visible windows displayed.
What makes MosaicLoader particularly dangerous is it can be used to deliver any payload onto a victim’s system. The malware has been observed delivering a broad range of malicious payloads, such as Remote Access Trojans (RATs) and backdoors, cookie stealers, and cryptocurrency miners. Based on the payloads delivered it is likely that, at least initially, MosaicLoader is being operated and used by one threat group, but it could easily be used under the malware-as-a-service model as a malware delivery service.
Protecting against MosaicLoader is straightforward in principle. Users should avoid downloading any cracked software. Not only is it illegal to download cracked software, but there is also a reasonable likelihood that doing so will install malware such as MosaicLoader, spyware, adware, and many potentially unwanted programs (PUPs). It is also necessary to have up to date antivirus/antimalware software installed.
Employees are always looking for ways to make their lives easier and installing unauthorized software – shadow IT – is common. Shadow IT may save an employee time during their working day, but it also carries risks, especially the installation of pirated software. This has become even more of a risk in the COVID-19 era with so many employees working from home.
Businesses can improve protection against MosaicLoader and other malware variants by carefully controlling the websites that employees can access on their corporate devices and under BYOD. Content filters, such as WebTitan, can be configured to restrict access to websites not required for work or block certain categories of website, as well as known malicious URLs.
Web filters can also be configured to block downloads of specific file types, such as software installers and other executable files often used to install malware. It should also be made clear to all staff that the downloading of unauthorized software onto corporate devices is prohibited, and that the installation of cracked software is illegal.
For further information on content filtering with a DNS filter and other cybersecurity measures you can implement to protect against malware, contact TitanHQ today. The WebTitan web filter is available on a free trial and can be implemented in minutes, and showing positive results in under an hour.