Urgent Alert: Protect Your Azure-Based Commvault Environment from CVE-2025-3928 Exploits

Racing against an escalating threat landscape, cybersecurity teams are on high alert following the disclosure of CVE-2025-3928—a critical vulnerability impacting Commvault environments running within Microsoft Azure. This zero-day flaw has become a focal point for threat actors, including those linked to nation-state operations, who are actively exploiting the weakness to gain footholds inside corporate environments. As the U.S. Cybersecurity and Infrastructure Security Agency (CISA) has added CVE-2025-3928 to its Known Exploited Vulnerabilities (KEV) catalog, the urgency for robust defense and detection has never been greater.

Understanding CVE-2025-3928: Commvault’s Achille’s Heel​

Commvault, an enterprise-grade data protection and backup solution, features extensively across Fortune 500 organizations and public enterprises—particularly those leveraging Microsoft Azure’s cloud infrastructure. CVE-2025-3928 specifically affects Commvault’s Web Server modules, covering all major deployments, including CommServe, Web Servers, and Command Center software.

How the Vulnerability Works​

According to verified advisories from both Commvault and leading security researchers, CVE-2025-3928 enables authenticated attackers to create and execute webshells on vulnerable Commvault web servers. The authentication requirement, while appearing to be a mitigating factor, has proven surmountable: sophisticated attackers have already been observed acquiring valid credentials through methods such as phishing, credential stuffing, or exploiting weak account policies.
Once authenticated, a threat actor can:

• Compromise the Commvault server by deploying arbitrary code (typically via webshells).
• Establish an undetectable presence to stage further attacks.
• Access sensitive configuration and, potentially, backup data, although Commvault asserts no evidence of backup data exfiltration as of the latest investigation.

Confirmation of Exploitation​

Commvault has publicly confirmed only a “small number” of customers have been impacted. However, the involvement of Microsoft and the move by CISA to highlight the bug on the KEV list indicate the scale and seriousness of the threat. Security teams are advised to treat all unpatched environments as likely targets, regardless of perceived obscurity.

Detecting Active Exploitation in Azure Using KQL​

While patching remains paramount, early detection forms the frontline of defense. Recognizing this, Steven Lim of KQLWizard published a targeted Kusto Query Language (KQL) script enabling Azure security teams to identify signs of compromise through the Azure Activity logs and SigninLogs.

Anatomy of the Detection Query​

The recommended KQL query operates as follows:

let CommVaultIOC = dynamic(["108.69.148.100", "128.92.80.210", "184.153.42.129", "108.6.189.53", "159.242.42.20"]);
let AzureActivityResult = AzureActivity
    | where TimeGenerated > ago(90d)
    | where CallerIpAddress has_any(CommVaultIOC);
SigninLogs
    | where TimeGenerated > ago(90d)
    | where IPAddress has_any(CommVaultIOC)
    | union AzureActivityResult

• Indicators of compromise (IOCs): A dynamic array of public IP addresses is used, all of which have been fingerprinted as part of the ongoing exploitation by Commvault and collaborating security teams.
• Log coverage: Both AzureActivity (tracking administrative actions) and SigninLogs (detailing authentication attempts) are queried for the past 90 days—a period reflecting the window of observed attacks.
• Action: Any matches trigger alerts for investigation.

This dual-log search is essential due to attackers often switching between credentialed logins and direct exploitation of the webserver interface.

Why KQL Is Ideal for Azure SOCs​

KQL's native integration with Azure Sentinel and Log Analytics Workspaces makes it ideal for rapid, at-scale searches across hybrid and cloud-native setups. Security teams running Commvault inside Azure can leverage this script directly within their SIEM platforms, minimizing detection latency and response times.

Real-World Risks: Assessing the Threat Landscape​

Strengths in Response​

• Swift Vendor Patching: Commvault’s transparent advisory and the rapid release of patches for actively supported versions—11.36.46, 11.32.89, 11.28.141, and 11.20.217—boost defenders’ odds.
• CISA Coordination: Mandating patch application by May 19, CISA’s involvement ensures federal customers move quickly and incentivizes private sector urgency.
• Industry Collaboration: Both Commvault and Microsoft’s security incident response teams continue to share threat intelligence and remediation guidance.

Remaining Weaknesses and Risks​

• Credential Acquisition: The “authenticated attacker” caveat is only as strong as an organization’s credential hygiene. Default, weak, or reused passwords—as well as compromised service principals—remain key vectors.
• Webshell Stealth: Once a webshell is planted, detection becomes significantly more difficult, especially in noisy environments or where SMBs lack dedicated threat hunting capabilities.
• Comprehensive Visibility Gaps: Organizations not using SIEM, or with incomplete log collection, may miss the subtle signs of exploitation until lateral movement is well underway.

Nation-State Interest: Why This Matters​

Multiple threat intelligence sources and CISA have confirmed the involvement of advanced persistent threat (APT) actors. While the specific group exploiting CVE-2025-3928 is under ongoing investigation, the tactics, techniques, and procedures (TTPs) align with historic operations aimed at cloud infrastructure supply chains. The potential for supply-chain lateral movement, data staging, and the targeting of governmental and critical infrastructure entities adds a national security dimension to the calculus.

Mitigation: Beyond Patching​

Patching is necessary but not sufficient for robust Commvault environment hardening.

Vendor-Recommended Steps​

• Apply Patches: Immediately update to one of the vendor’s fixed versions for all affected Windows and Linux deployments.
• Rotate Credentials: Change and resync client secrets between the Azure portal and Commvault environments at least every 90 days, closing the window for credential re-use.
• Enforce Conditional Access: Design policies to limit access to Commvault instances only from managed, geofenced, and allowlisted IP ranges.
• Block Malicious IPs: Explicitly add known IOCs to IP block lists within Conditional Access policies or network firewalls, denying further attempts.
• Monitor Sign-in Activity: Set real-time alerts for authentication activity from outside authorized geographic or network regions.
• Prompt Response: Immediately escalate and report suspicious activity to Commvault’s support and Microsoft’s incident response channels.

Cybersecurity Best Practices​

• Multi-factor Authentication (MFA): Mandatory for all administrative accounts, reducing the chance of credential-only compromise.
• Zero Trust Principles: Regularly audit privilege assignments so even compromised accounts possess the minimum possible access necessary.
• SIEM and SOAR Integration: Sync the provided KQL queries with wider security orchestration playbooks to automate investigation and containment.
• Regular Penetration Testing: Simulate exploitation of web interfaces and authentication systems to unearth new weaknesses ahead of actors.
• Training and Awareness: Summon IT and security teams for briefings on this specific threat and update incident response plans accordingly.

The Broader Security Context: Trends and Takeaways​

Azure as a Double-Edged Sword​

The transition to cloud-native data protection brings operational agility—but also multiplies the attack surface. Organizations must treat vendor-centric applications like Commvault for Azure as part of their broader cloud security architecture, not isolated islands. This means bridging gaps between IT, security, and application operations.

The Importance of Visibility and Early Warning​

The release and endorsement of easily deployable KQL queries exemplifies a trend toward proactive, transparent incident detection. However, without buy-in from senior leadership and routine integration into SOC workflows, such capabilities can languish unused.

Patch Fatigue and Legacy Software​

As with many critical vulnerabilities, a subset of customers invariably lags on patching due to custom integrations, lack of support contracts, or business inertia. These legacy environments are not only at risk—they become stepping stones for attackers seeking to pivot elsewhere.

Nation-State Actors as Early Adopters​

The inclusion of CVE-2025-3928 in ongoing APT toolkits reaffirms that criminal and state-aligned groups increasingly scan for and weaponize critical vulnerabilities within days of disclosure. This requires organizations to close vulnerability-to-patch windows as tightly as possible.

Critical Analysis: Strengths, Weaknesses, and Next Steps​

Key Strengths​

• Transparent, timely disclosure and vendor guidance.
• Effective industry-government collaboration (CISA, Microsoft, Commvault).
• Practical tools (KQL queries) immediately usable by SOCs and defenders.

Major Weaknesses​

• Credential dependency for exploitation is weak protection—attackers can credential stuff/harvest.
• Small organizations may lack resources or logging maturity to implement guidance.
• Many organizations historically lag on patch management, despite ongoing risk campaigns.

Potential Risks and Future Scenarios​

• Unpatched Environments as Persistent Weaknesses: Expect further expansion of attacks as slow-moving organizations fail to update.
• Living-off-the-Land Attacks: Once inside, actors may leverage legitimate backup functions to stage further attacks or exfiltrate valuable assets.
• Ransomware/Supply Chain Pivot: Webshell footholds could be leveraged to deploy ransomware or as a jump point to supply chain targets.

Actionable Recommendations​

• Organizations using Commvault in Azure must update immediately, regardless of perceived current exposure.
• Security teams should implement the KQL query today and tune workflows for rapid response to future IOCs.
• Credential hygiene, least privilege, and conditional access should be treated as ongoing operational baselines—not one-time fixes.
• Monitor CISA and vendor advisories for new patches, additional IOCs, and evolving TTPs from threat actors.

Conclusion​

CVE-2025-3928 marks another milestone in the ongoing battle to keep cloud-centric data protection infrastructure secure. Nation-state exploitation underscores that even foundational technologies like backup servers are now prime targets. By acting decisively—patching, detecting active threats using KQL and Azure’s extensive logs, and staying vigilant through comprehensive security best practices—organizations can reduce their risk, maintain business continuity, and secure their operational data lifeblood against evolving adversaries.
Ensuring the security of Commvault within Azure is not a one-and-done affair but an ongoing commitment shaped by timely intelligence sharing, practical threat detection, and a willingness to adapt as new vulnerabilities inevitably emerge.

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Source: CybersecurityNews Detecting Vulnerable Commvault Environments Within Azure Using KQL Query