CVE-2001-0261 in Windows
Summary
by MITRE
Microsoft Windows 2000 Encrypted File System does not properly destroy backups of files that are encrypted, which allows a local attacker to recover the text of encrypted files.
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Analysis
by VulDB Data Team • 04/07/2017
The vulnerability described in CVE-2001-0261 affects Microsoft Windows 2000 Encrypted File System implementation where encrypted files are not properly secured during the backup process. This flaw represents a critical security weakness in the operating system's file encryption mechanisms, specifically targeting the backup and recovery procedures that should ensure encrypted data remains protected. The issue stems from the improper handling of backup copies of encrypted files, creating a scenario where local attackers can potentially recover plaintext content from these backup files. This vulnerability directly impacts the confidentiality assurances that encrypted files are supposed to provide, undermining the fundamental security model of the EFS subsystem.
The technical implementation flaw occurs within the Windows 2000 EFS backup handling code where backup operations fail to properly destroy or encrypt backup copies of encrypted files. When users perform backup operations on encrypted files, the system creates backup copies that retain the original encryption keys or encryption context in a manner that allows unauthorized access to the plaintext content. This behavior violates the expected security properties of encryption systems where backup files should either be encrypted with different keys or properly secured to prevent unauthorized access. The vulnerability is particularly concerning because it affects local attackers who already have access to the system, making it a privilege escalation issue within the existing security boundaries.
The operational impact of this vulnerability extends beyond simple data exposure, as it fundamentally compromises the integrity of the Windows 2000 EFS security model. Local attackers can exploit this weakness to recover sensitive information from backup files without requiring additional privileges or external attack vectors. The vulnerability affects organizations that rely on EFS for protecting sensitive data, as it creates a backdoor for unauthorized access to encrypted content through legitimate backup procedures. This weakness can be particularly damaging in environments where backup files are stored in accessible locations or where backup operations are performed by users with varying levels of access control. The impact is amplified when considering that backup files often contain copies of files that may be deleted or moved but remain accessible through backup systems.
Organizations should implement immediate mitigations including disabling unnecessary backup operations for encrypted files, implementing additional access controls for backup systems, and ensuring that backup files are properly secured with separate encryption mechanisms. System administrators should review backup policies and ensure that encrypted files are either excluded from standard backup procedures or that backup copies are properly encrypted using different key management approaches. The vulnerability aligns with CWE-310, which addresses cryptographic weaknesses in backup and recovery processes, and represents a clear violation of the principle of least privilege in backup file handling. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation and credential access techniques where attackers exploit system weaknesses to gain unauthorized access to protected information through legitimate system functions. Organizations should also consider implementing monitoring for backup operations on encrypted files and establishing procedures for regular security assessments of backup and recovery processes to prevent similar vulnerabilities from persisting in updated systems.