CVE-2020-14957 in Windows Cleaning Assistant
Summary
by MITRE
In Windows cleaning assistant 3.2, the driver file (AtpKrnl.sys) allows local users to cause a denial of service (BSOD) or possibly have unspecified other impact because of not validating input values from IOCtl 0x223CCD.
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Analysis
by VulDB Data Team • 07/01/2020
The vulnerability identified as CVE-2020-14957 affects the Windows Cleaning Assistant 3.2 software suite, specifically targeting the kernel-mode driver component known as AtpKrnl.sys. This driver serves as a critical system interface for the cleaning assistant functionality, handling various system-level operations through Windows I/O control codes. The flaw manifests in the driver's insufficient validation of input parameters received through IOCTL 0x223CCD, which represents a specific control code used for communication between user-mode applications and kernel-mode drivers. This particular IOCTL handler demonstrates a classic security weakness where the driver fails to properly sanitize or validate incoming data before processing it within the kernel space.
The technical implementation of this vulnerability stems from a lack of input validation mechanisms within the driver's IOCTL processing routine. When a local user application sends data to the driver through the specified IOCTL 0x223CCD, the AtpKrnl.sys driver does not perform adequate checks on the supplied parameters, including buffer sizes, data types, or boundary conditions. This absence of validation creates a potential exploitation vector where malformed or malicious input data can cause the driver to behave unpredictably. The vulnerability can result in a blue screen of death (BSOD) due to the kernel-mode driver crashing when encountering unexpected input values, effectively causing a system-wide denial of service condition. The unspecified nature of other potential impacts suggests that beyond the immediate denial of service, the vulnerability might allow for privilege escalation or other security breaches depending on the specific malformed input patterns used.
From an operational perspective, this vulnerability presents a significant risk to systems running the affected Windows Cleaning Assistant software, particularly in enterprise environments where local user access is common. The local privilege requirement means that an attacker with access to a user account on the system can potentially exploit this vulnerability without requiring administrative privileges, making it particularly dangerous in multi-user environments. The impact extends beyond simple service disruption as the BSOD condition can cause data loss, system instability, and potential downtime for critical business operations. The vulnerability's presence in a cleaning assistant tool is particularly concerning as these applications often require elevated privileges to function properly, potentially increasing the attack surface and exploitation potential. According to CWE classification, this vulnerability maps to CWE-129 Input Validation, which specifically addresses the weakness of insufficient validation of input values that can lead to buffer overflows and other memory corruption issues.
The exploitation of CVE-2020-14957 aligns with ATT&CK techniques focusing on privilege escalation and denial of service attacks. The vulnerability demonstrates characteristics of T1068, which involves local privilege escalation through exploitation of system vulnerabilities, and T1490, covering denial of service attacks that target system resources. The fact that this is a kernel-mode vulnerability means that successful exploitation can potentially provide attackers with elevated privileges and access to system resources that would otherwise be protected. Security researchers have noted that such driver-level vulnerabilities are particularly dangerous because they operate at the highest privilege level within the Windows kernel, making them attractive targets for advanced persistent threats. The vulnerability also reflects broader trends in Windows driver security issues where insufficient input validation in kernel-mode components creates pathways for both denial of service and potential privilege escalation attacks.
Mitigation strategies for this vulnerability should include immediate patching of the Windows Cleaning Assistant software to the latest version that addresses the input validation flaw. System administrators should implement the principle of least privilege, limiting local user access to systems running vulnerable software and ensuring that only authorized personnel have the ability to interact with the cleaning assistant functionality. Additional defensive measures include monitoring for unusual IOCTL activity patterns and implementing kernel-mode protection mechanisms such as Driver Signature Enforcement and Windows Defender Application Control to prevent unauthorized driver loading. Organizations should also consider disabling the cleaning assistant functionality entirely if it is not required for business operations, as this eliminates the attack surface associated with the vulnerable driver component. The vulnerability underscores the importance of proper input validation in kernel-mode drivers and serves as a reminder of the critical security requirements for system-level software components that operate with elevated privileges.