CVE-2007-0843 in Windows
Summary
by MITRE
The ReadDirectoryChangesW API function on Microsoft Windows 2000, XP, Server 2003, and Vista does not check permissions for child objects, which allows local users to bypass permissions by opening a directory with LIST (READ) access and using ReadDirectoryChangesW to monitor changes of files that do not have LIST permissions, which can be leveraged to determine filenames, access times, and other sensitive information.
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Analysis
by VulDB Data Team • 07/13/2021
The vulnerability described in CVE-2007-0843 represents a significant permission bypass issue within the Windows file system monitoring API. This flaw exists in the ReadDirectoryChangesW function across multiple Windows operating systems including Windows 2000, XP, Server 2003, and Vista. The core issue stems from the function's failure to properly validate permissions for child objects within directories, creating a pathway for unauthorized information disclosure. The vulnerability operates under CWE-284 which specifically addresses improper access control mechanisms, making it a classic example of insufficient privilege checking in system APIs. This weakness allows attackers to exploit the gap in permission enforcement by leveraging legitimate system calls to gather sensitive information about files that would normally be restricted.
The technical implementation of this vulnerability exploits the fundamental design flaw in how Windows handles directory change notifications. When a local user possesses only LIST (READ) permissions on a directory, they can utilize ReadDirectoryChangesW to monitor changes within that directory structure. The function's improper validation means it does not verify whether the user has appropriate permissions to access the specific child objects being monitored. This creates a scenario where users can observe file creation, deletion, and modification events for files they cannot normally access, effectively providing them with information about the existence and access patterns of restricted files. The operational impact extends beyond simple information disclosure, as it can reveal directory structures, file naming conventions, and access timing information that could be leveraged in subsequent attacks.
From an operational security perspective, this vulnerability presents a serious risk to organizations relying on Windows systems, particularly those with sensitive data repositories. The ability to determine filenames and access times through legitimate API usage means that attackers can map out directory structures and identify potentially valuable targets without triggering traditional access control mechanisms. This vulnerability aligns with ATT&CK technique T1083 which covers directory and file discovery activities, but operates at a lower level by exploiting API design flaws rather than user enumeration techniques. The local nature of this vulnerability means that it requires physical or network access to the system, but once exploited, it can provide attackers with detailed information about file system access patterns and potentially reveal sensitive organizational data.
Mitigation strategies for this vulnerability should focus on both immediate system hardening and long-term architectural improvements. Microsoft released patches for affected systems, but organizations should also implement additional monitoring to detect unusual directory change activity patterns that might indicate exploitation attempts. System administrators should review and audit directory permissions to ensure that the principle of least privilege is properly enforced, particularly for directories that contain sensitive information. Network segmentation and access control lists can help limit the potential impact of successful exploitation attempts. The vulnerability demonstrates the importance of proper API design and permission validation in system security, and serves as a reminder that even legitimate system functions can become security risks when they fail to properly enforce access controls. Organizations should also consider implementing file integrity monitoring solutions that can detect unauthorized changes to directory structures and file access patterns that might indicate exploitation of this or similar vulnerabilities.