Cloud Breach 2025: Anatomy of the Commvault Azure Attack (CVE-2025-3928)
I. Executive Summary The “Cloud Breach 2025” event, simulating a hypothetical breach, highlights the critical role of backup systems as high-value targets for attackers. The incident in question focuses on the CVE-2025-3928 vulnerability in a Commvault environment integrated with Azure, illustrating the potential cascading impact of such a breach on organizational data and operations. The increasing complexity of cloud environments, combined with intricate software integrations like Commvault with Azure, creates a fertile ground for sophisticated cyberattacks. A specific vulnerability like CVE-2025-3928 can serve as a critical entry point, bypassing general cloud security measures if not properly addressed. The impact is not limited to the backup system alone but can extend to the organization’s entire cloud estate. This report analyzes the anatomy of such an attack and demonstrates how a multi-layered security approach, as exemplified by the capabilities of Cybecs, is essential for prevention and damage mitigation. In light of this, proactive and specialized cybersecurity measures are no longer optional but a fundamental requirement for organizations leveraging cloud-based backup solutions.   II. The Convergence of Risks: Commvault in the Azure Cloud Environment A. Commvault’s Architecture and Its Critical Importance in Organizational Data Protection Commvault’s software platform is an enterprise-level, integrated data and information management solution, built from the ground up on a single platform and unified codebase. All functions share common back-end technologies to deliver holistic advantages for data protection, management, and access. The software includes modules for data protection and archiving, analysis, replication, and search, all sharing a common set of back-end services and advanced capabilities, interacting seamlessly with one another. This approach addresses all aspects of data management in the enterprise, providing infinite scalability and unprecedented control over data and information. The core components of Commvault include the CommServe, a central server that tracks all data management activity in the environment and allows administrators to manage it through a central user interface. The MediaAgent is a data manager that processes data from client computers and backs it up to disk, tape, or cloud storage. Software agents are installed on physical or virtual hosts and protect production data using native operating system or application APIs to ensure data protection in a consistent state. This platform provides a comprehensive protection solution supporting all major operating systems, applications, and databases on virtual and physical servers, NAS storage, cloud-based infrastructures, and mobile devices. The importance of Commvault in ensuring business continuity and disaster recovery makes its security paramount. Its ability to handle diverse workloads, including cloud applications and large data volumes, such as backing up and restoring billions of S3 objects, underscores its central role in an organization’s data strategy. B. Deep Dive: Commvault’s Integration Mechanisms with Microsoft Azure Commvault integrates closely with Microsoft Azure to provide backup and restore capabilities for resources hosted in the cloud. To protect virtual machines (VMs) in Azure, Commvault allows the creation of a “virtualization client” for each Azure subscription. This client can include multiple proxy servers where the Virtual Server Agent (VSA) is installed to perform backup operations. The software automatically creates an Azure instance, a backup set, and a default subclient to protect all virtual machines, with the option to create additional subclients for separate protection of different VM groups. There are two main methods for Azure Resource Manager (ARM) deployment with Commvault: Additionally, Commvault can use Azure AD as an identity provider (IdP) for user login to the Commvault system, via SAML application integration. This process involves sharing metadata between the Azure application (the IdP) and the Commvault Command Center application (the Service Provider – SP). This tight integration, despite its functional benefits, inherently creates new attack vectors if not secured meticulously, as the access credentials and service accounts used for integration become high-value targets for attackers. The architecture of a Commvault deployment can include components such as the CommServe and access nodes hosted within Azure or in hybrid environments connecting to Azure. The CommServe, as the “central server” tracking all activity and managed via a “central user interface” , along with the Command Center (web-based) and the CommCell Console (advanced interface) , represent critical choke points. A vulnerability in these components, or in their underlying web server infrastructure, could grant extensive control over all backup and restore operations and connected cloud resources. C. Inherent Security Challenges in Hybrid Backup Architectures Hybrid backup architectures, combining on-premises and cloud resources, present unique security challenges. The expanded attack surface includes APIs, network connections, and complexities in the shared responsibility model. Common vulnerabilities in backup and recovery software include weak access and password management, unpatched systems and software, lack of sufficient encryption, insider threats, and inadequate backup and disaster recovery plans. A key risk is the compromise of access credentials, such as application secrets or service principal credentials, used for communication between Commvault and Azure. These credentials, if exposed, could allow attackers unauthorized access to critical cloud resources. The fact that the backup system holds the “keys to the kingdom” – i.e., credentials with extensive permissions in the cloud environment – makes it a particularly attractive target. The security of the backup system is no longer isolated; it is inherently linked to the security of the cloud environment it protects. Specific Commvault security recommendations for Azure include applying a Conditional Access policy to all single-tenant App registrations for Microsoft 365, Dynamics 365, and Azure AD, as well as rotating and syncing client secrets between the Azure portal and Commvault every 90 days. Additionally, it is recommended to regularly monitor sign-in activity to detect access attempts from IP addresses not on the whitelist. Commvault also provides custom roles with the necessary permissions to protect Azure resources, recommending their use in production environments over broader built-in roles. III. CVE-2025-3928: The Achilles’ Heel A. Technical Profile of Vulnerability CVE-2025-3928 The CVE-2025-3928 vulnerability, as described in the context of the “Cloud Breach 2025” event, represents a critical weak point in the defense posture of organizations using Commvault in Azure environments. According to available information, this is a zero-day vulnerability identified in Commvault’s web server. This vulnerability allows remote, authenticated attackers to execute arbitrary code remotely
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