CVE-2021-24079 in Windows
Summary
by MITRE • 02/26/2021
Windows Backup Engine Information Disclosure Vulnerability
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Analysis
by VulDB Data Team • 06/14/2026
This vulnerability affects the Windows Backup Engine component and represents a critical information disclosure flaw that allows unauthorized access to sensitive backup data and system information. The vulnerability stems from improper access controls within the backup engine's architecture, enabling malicious actors to extract confidential information without proper authentication. This weakness falls under the broader category of insufficient access control issues as classified by CWE-284, where the backup engine fails to properly enforce authorization mechanisms for backup operations. The flaw exists in the way the system handles backup metadata and file access permissions, creating potential pathways for data leakage through improperly protected backup repositories. Attackers can exploit this vulnerability to gain insights into backup schedules, file structures, and potentially access backup files that should remain protected. The impact extends beyond simple information disclosure as it can provide adversaries with detailed knowledge of system backup configurations and data organization patterns. This information can significantly aid in planning more sophisticated attacks targeting backup systems, potentially leading to complete system compromise. The vulnerability manifests when the backup engine processes requests without adequate validation of user credentials or access permissions, allowing unauthorized entities to query backup engine components directly. According to ATT&CK framework, this represents a technique under T1211 - Exfiltration Over Other Network Medium, where attackers leverage backup systems as a means to access and extract sensitive data. The flaw is particularly dangerous in enterprise environments where backup systems often contain comprehensive copies of organizational data, including sensitive user information, system configurations, and business-critical files. Security researchers have identified that the vulnerability can be exploited through network-based attacks targeting specific backup engine ports and services, making it a significant concern for organizations relying on Windows backup solutions. The vulnerability affects multiple Windows versions and can be triggered through various attack vectors including remote network access and local system exploitation. Organizations should consider this as a high-priority security concern due to the potential for widespread data exposure across backup repositories. The backup engine's information disclosure vulnerability creates a cascading effect where initial unauthorized access can lead to further exploitation opportunities, as attackers can use the leaked information to craft more targeted attacks against the system infrastructure. Proper access control implementation is essential to prevent unauthorized users from querying backup engine components and accessing protected backup data. This vulnerability demonstrates the critical importance of securing backup systems as they often represent the most comprehensive data repositories within an organization's infrastructure. The flaw underscores the need for robust authentication mechanisms and proper privilege management within backup engine components, ensuring that only authorized personnel can access backup operations and data. Organizations should implement immediate mitigations including access control hardening, network segmentation, and regular security assessments of backup system configurations to prevent exploitation of this information disclosure vulnerability.
This vulnerability represents a significant security weakness in Windows backup engine implementations that directly impacts data confidentiality and system integrity. The root cause lies in the backup engine's failure to properly enforce access controls when processing backup-related requests, creating opportunities for unauthorized information extraction. From a cybersecurity perspective, this vulnerability aligns with CWE-284 access control flaws where insufficient authorization checks allow privilege escalation or unauthorized data access. The backup engine component operates with inadequate validation of user credentials and access permissions, enabling malicious actors to query system backup information without proper authentication. This type of vulnerability is particularly concerning because backup systems typically contain comprehensive copies of organizational data, including user credentials, system configurations, and sensitive business information. The operational impact includes potential data leakage that can compromise entire organizational security postures, as backup repositories often serve as gold mines for attackers seeking comprehensive system information. According to ATT&CK framework, this vulnerability enables T1211 - Exfiltration Over Other Network Medium by providing attackers with access to backup systems as data repositories. The attack surface is widened when backup engines are accessible over network connections, allowing remote exploitation without requiring physical access to systems. This information disclosure can facilitate subsequent attacks including privilege escalation, lateral movement, and complete system compromise. The vulnerability exists across multiple Windows versions and can be exploited through various attack vectors including network-based probing and direct system access. Organizations must recognize that backup systems are often overlooked security components, yet they represent critical attack targets due to their comprehensive data access capabilities. The flaw demonstrates the importance of implementing proper access controls and authentication mechanisms within backup engine components to prevent unauthorized access to backup operations and data repositories. Security teams should prioritize immediate remediation efforts including access control configuration reviews, network segmentation, and implementation of monitoring solutions to detect unauthorized backup engine access attempts.