Cybersecurity researchers have uncovered a novel malware marketing campaign that leverages Google Sheets as a command-and-control (C2) mechanism.
The exercise, detected by Proofpoint beginning August 5, 2024, impersonates tax authorities from governments in Europe, Asia, and the U.S., with the purpose of concentrating on over 70 organizations worldwide via a bespoke software known as Voldemort that is outfitted to collect data and ship further payloads.
Focused sectors embody insurance coverage, aerospace, transportation, academia, finance, expertise, industrial, healthcare, automotive, hospitality, vitality, authorities, media, manufacturing, telecom, and social profit organizations.
The suspected cyber espionage marketing campaign has not been attributed to a selected named menace actor. As many as 20,000 e-mail messages have been despatched as a part of the assaults.
These emails declare to be from tax authorities within the U.S., the U.Ok., France, Germany, Italy, India, and Japan, alerting recipients about modifications to their tax filings and urging them to click on on Google AMP Cache URLs that redirect customers to an intermediate touchdown web page.
What the web page does is examine the Consumer-Agent string to find out if the working system is Home windows, and if that’s the case, leverage the search-ms: URI protocol handler to show a Home windows shortcut (LNK) file that makes use of an Adobe Acrobat Reader to masquerade as a PDF file in an try to trick the sufferer into launching it.
“If the LNK is executed, it can invoke PowerShell to run Python.exe from a 3rd WebDAV share on the identical tunnel (library), passing a Python script on a fourth share (useful resource) on the identical host as an argument,” Proofpoint researchers Tommy Madjar, Pim Trouerbach, and Selena Larson mentioned.
“This causes Python to run the script with out downloading any recordsdata to the pc, with dependencies being loaded immediately from the WebDAV share.”
The Python script is designed to collect system data and ship the info within the type of a Base64-encoded string to an actor-controlled area, after which it exhibits a decoy PDF to the person and downloads a password-protected ZIP file from OpenDrive.
The ZIP archive, for its half, accommodates two recordsdata, a reputable executable “CiscoCollabHost.exe” that is vulnerable to DLL side-loading and a malicious DLL “CiscoSparkLauncher.dll” (i.e., Voldemort) file that is sideloaded.
Voldemort is a customized backdoor written in C that comes with capabilities for data gathering and loading next-stage payloads, with the malware using Google Sheets for C2, knowledge exfiltration, and executing instructions from the operators.
Proofpoint described the exercise as aligned to superior persistent threats (APT) however carrying “cybercrime vibes” owing to using methods standard within the e-crime panorama.
“Risk actors abuse file schema URIs to entry exterior file sharing assets for malware staging, particularly WebDAV and Server Message Block (SMB). That is finished through the use of the schema ‘file://’ and pointing to a distant server internet hosting the malicious content material,” the researchers mentioned.
This method has been more and more prevalent amongst malware households that act as preliminary entry brokers (IABs), similar to Latrodectus, DarkGate, and XWorm.
Moreover, Proofpoint mentioned it was in a position to learn the contents of the Google Sheet, figuring out a complete of six victims, together with one which’s believed to be both a sandbox or a “recognized researcher.”
The marketing campaign has been branded uncommon, elevating the chance that the menace actors solid a large web earlier than zeroing in on a small pool of targets. It is also doable that the attackers, probably with various ranges of technical experience, deliberate to contaminate a number of organizations.
“Whereas most of the marketing campaign traits align with cybercriminal menace exercise, we assess that is probably espionage exercise performed to assist as but unknown ultimate targets,” the researchers mentioned.
“The Frankensteinian amalgamation of intelligent and complicated capabilities, paired with very fundamental methods and performance, makes it troublesome to evaluate the extent of the menace actor’s functionality and decide with excessive confidence the final word objectives of the marketing campaign.”
The event comes as Netskope Risk Labs uncovered an up to date model of the Latrodectus (model 1.4) that comes with a brand new C2 endpoint and provides two new backdoor instructions that enable it to obtain shellcode from a specified server and retrieve arbitrary recordsdata from a distant location.
“Latrodectus has been evolving fairly quick, including new options to its payload,” safety researcher Leandro Fróes mentioned. “The understanding of the updates utilized to its payload permits defenders to maintain automated pipelines correctly set in addition to use the data for additional looking for new variants.”
