The Scranos rootkit-enabled spyware operation has expanded reach outside of China to hit targets worldwide, Bitdefender security researchers warn.
Spreading via trojanized applications posing as cracked software or legitimate programs (such as e-book readers, video players, drivers, or anti-malware products), the malware initially operated in China only, but is now prevalent in India, Romania, Brazil, France, Italy and Indonesia as well.
The initial stage of the infection involves the use of a dropper that also functions as a password stealer. It installs a rootkit driver to achieve persistence and hide the malicious activity from the user.
To survive reboots, the rootkit is rewriting itself at shutdown. However, because it doesn’t hide itself, it can be deleted if detected — other malicious components are deleted after use, because they can be easily re-downloaded if needed.
Next, the rootkit beacons the command and control (C&C) server to receive commands on what components to download and install. It injects the downloader into a legitimate svchost.exe process and abuses it to fetch the payloads.
According to Bitdefender, the malware operators are testing various components on already infected users to serve different purposes or achieve additional goals.
Based on these components, Scranos can extract cookies and login credentials from popular browsers, steal browsing history, steal payment accounts (from Facebook, Amazon, and Airbnb), send friend requests on Facebook or phishing emails to the victim’s Facebook friends, and steal Steam login info.
It can also inject adware into Internet Explorer, install browser extensions for Chrome and Opera to inject adware, silently display ads or muted YouTube videos via Chrome, subscribe users to YouTube channels, and download and execute additional payloads.
The operation, the researchers say, is in a consolidation stage, with the oldest sample dated November 2018 and a spike in detections observed in December 2018 and January 2019. Last month, however, the C&C servers started delivering other malware variants, suggesting third-party affiliation.
Scranos was also observed interacting with websites on victims’ behalf, as well as aggressively promoting four YouTube videos on various channels.
To manipulate YouTube pages, the malware uses Chrome in debugging mode — in some instances it even installs the browser if the user hasn’t. It hides the Chrome window from the desktop and taskbar to keep the user from observing the malicious activity.
Bitdefender also says they discovered variants of the main dropper that packs the same functionality but slightly different methods. Some payload variants were observed featuring different C&C addresses or manipulating other pages instead of YouTube.
The researchers also noticed a completely different payload being delivered in some cases, which suggests that a third-party is pushing this malicious content, not the Scranos operators. This suggests that the established botnet is being rented for profit.
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Ionut Arghire is an international correspondent for SecurityWeek.
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