Back 
In a previous memo, I mentioned the discovery, made by researchers at Kaspersky, of an active campaign carried out by an advanced threat actor since 2021, targeting multiple organizations in the regions of Donetsk, Lugansk, and Crimea. One of the noteworthy aspects of this campaign was undoubtedly the usage of a new backdoor, called PowerMagic, characterized by the exploitation of the popular cloud storage services, Dropbox and OneDrive, as the command and control infrastructure.
Recently, researchers from Malwarebytes shed some light on the same threat actor, which they dubbed Red Stinger, revealing that the extent of their operation was, in reality, wider than initially thought (going back to at least December 2020 rather than September 2021 as indicated by researchers from Kaspersky). All of the campaigns conducted by the same threat actor have had a lowest common denominator: the exploitation of Dropbox as command and control via the same PowerMagic backdoor, which the Malwarebytes researchers dubbed DBoxShell.
In particular, from late 2020 to the end of 2022, the researchers laid bare five campaigns from the same threat actor targeting objectives in the same area (including the one recently unearthed and described in the previous memo). Despite there being some differences in the attack chain, over the years, the attackers used the same modus operandi, leveraging malicious MSI files to drop an encoded version of the DBoxShell payload and using an XOR operation to implant it in the target system.
Additionally, in the last known activity of Red Stinger, the attackers used an additional backdoor dubbed GraphShell that, as the name suggests, leverages the Microsoft Graph API for the command and control infrastructure. A different cloud service, but the same malicious purpose…
How Netskope mitigates the risk of legitimate cloud services exploited for the C&C infrastructure
Dropbox and OneDrive are among the thousands of services where the Netskope Next Gen SWG can provide granular access control, threat protection, and DLP capabilities and also among the hundreds of services for which instance detection is available.
When a legitimate cloud service is exploited to host the command and control, it is possible to configure a policy that prevents potentially dangerous activities (such as upload and download) for unmanaged cloud services or non-corporate instances of managed cloud services.
And if a legitimate cloud service is exploited to distribute malware, it is possible to configure a policy that prevents potentially dangerous activities (such as download) from non-corporate instances, or in general from any unneeded cloud storage service for the enterprise.
Netskope customers are also protected against malware distributed from a legitimate cloud service and the web in general by Netskope Threat Protection. Netskope Threat Protection scans web and cloud traffic to detect known and unknown threats with a comprehensive set of engines, including signature-based AV, machine learning-based detectors for executables and Office documents, and sandboxing, including patient zero protection.
Netskope Cloud Exchange provides powerful integration tools to leverage investments across their security posture through integration with third-party tools, such as threat intelligence feeds and endpoint detection technologies.
Finally, Netskope Advanced Analytics provides specific dashboards to assess the risk of rogue cloud instances being exploited to deliver malware or becoming the target of anomalous communications, with rich details and insights, supporting security teams in the analysis and mitigation/remediation process.
Stay safe!
Read the blog