The risk actor often called Cloud Atlas has been noticed utilizing a beforehand undocumented malware known as VBCloud as a part of its cyber assault campaigns focusing on “a number of dozen customers” in 2024.
“Victims get contaminated by way of phishing emails containing a malicious doc that exploits a vulnerability within the system editor (CVE-2018-0802) to obtain and execute malware code,” Kaspersky researcher Oleg Kupreev stated in an evaluation revealed this week.
Greater than 80% of the targets have been situated in Russia. A lesser variety of victims have been reported from Belarus, Canada, Moldova, Israel, Kyrgyzstan, Turkey, and Vietnam.
Additionally known as Clear Ursa, Inception, Oxygen, and Crimson October, Cloud Atlas is an unattributed risk exercise cluster that has been lively since 2014. In December 2022, the group was linked to cyber assaults aimed toward Russia, Belarus, and Transnistria that deployed a PowerShell-based backdoor known as PowerShower.
Then precisely a yr later, Russian cybersecurity firm F.A.C.C.T. revealed that varied entities within the nation have been focused by spear-phishing assaults that exploited an previous Microsoft Workplace Equation Editor flaw (CVE-2017-11882) to drop a Visible Primary Script (VBS) payload answerable for downloading an unknown next-stage VBS malware.
Kaspersky’s newest report reveals that these elements are a part of what it calls VBShower, which is then used to obtain and set up PowerShower in addition to VBCloud.
The place to begin of the assault chain is a phishing electronic mail that incorporates a booby-trapped Microsoft Workplace doc that, when opened, downloads a malicious template formatted as an RTF file from a distant server. It then abuses CVE-2018-0802, one other flaw within the Equation Editor, to fetch and run an HTML Software (HTA) file hosted on the identical server.
“The exploit downloads the HTA file by way of the RTF template and runs it,” Kupreev stated. “It leverages the alternate information streams (NTFS ADS) function to extract and create a number of information at %APPDATApercentRoamingMicrosoftWindows. These information make up the VBShower backdoor.”
This features a launcher, which acts as a loader by extracting and operating the backdoor module in reminiscence. The opposite VB Script is a cleaner that cares about erasing the contents of all information contained in the “LocalMicrosoftWindowsTemporary Web FilesContent.Phrase” folder, along with these inside itself and the launcher, thereby protecting up proof of the malicious exercise.
The VBShower backdoor is designed to retrieve extra VBS payloads from the command-and-control (C2) server that comes with capabilities to reboot the system; collect details about information in varied folders, names of operating processes, and scheduler duties; and set up PowerShower and VBCloud.
PowerShower is analogous to VBShower in performance, the chief distinction being that it downloads and executes next-stage PowerShell scripts from the C2 server. It is also geared up to function a downloader for ZIP archive information.
As many as seven PowerShell payloads have been noticed by Kaspersky. Every of them carries out a definite process as follows –
- Get an inventory of native teams and their members on distant computer systems by way of Energetic Listing Service Interfaces (ADSI)
- Conduct dictionary assaults on consumer accounts
- Unpack ZIP archive downloaded by PowerShower and execute a PowerShell script contained inside it to be able to perform a Kerberoasting assault, which is a post-exploitation approach for acquiring credentials for Energetic Listing accounts
- Get an inventory of administrator teams
- Get an inventory of area controllers
- Get details about information contained in the ProgramData folder
- Get the account coverage and password coverage settings on the native pc
VBCloud additionally features quite a bit like VBShower, however makes use of public cloud storage service for C2 communications. It will get triggered by a scheduled process each time a sufferer consumer logs into the system.
The malware is supplied to reap details about disks (drive letter, drive sort, media sort, dimension, and free area), system metadata, information and paperwork matching extensions DOC, DOCX, XLS, XLSX, PDF, TXT, RTF, and RAR, and information associated to the Telegram messaging app.
“PowerShower probes the native community and facilitates additional infiltration, whereas VBCloud collects details about the system and steals information,” Kupreev stated. “The an infection chain consists of a number of levels and in the end goals to steal information from victims’ units.”