CVE-2021-1660 in Windows
Summary
by MITRE • 01/13/2021
Remote Procedure Call Runtime Remote Code Execution Vulnerability This CVE ID is unique from CVE-2021-1658, CVE-2021-1664, CVE-2021-1666, CVE-2021-1667, CVE-2021-1671, CVE-2021-1673, CVE-2021-1700, CVE-2021-1701.
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Analysis
by VulDB Data Team • 10/09/2024
The CVE-2021-1660 vulnerability represents a critical remote code execution flaw within the Remote Procedure Call Runtime component of Microsoft Windows operating systems. This vulnerability specifically affects the RPC runtime environment that facilitates communication between different processes and systems, making it a prime target for attackers seeking to compromise enterprise networks. The flaw exists in how the RPC runtime handles certain input validation processes, creating a pathway for malicious actors to execute arbitrary code on affected systems without requiring authentication. The vulnerability is particularly concerning because RPC is fundamental to Windows network operations, including domain controller communications, file sharing, and system management functions that are essential to enterprise infrastructure.
The technical implementation of this vulnerability stems from improper input validation within the RPC runtime library, which fails to properly sanitize data structures during remote procedure calls. Attackers can exploit this weakness by crafting malicious RPC requests that trigger buffer overflows or memory corruption conditions within the vulnerable component. This type of vulnerability falls under CWE-121, which describes stack-based buffer overflow conditions, and may also align with CWE-787, representing out-of-bounds write vulnerabilities. The flaw allows for privilege escalation scenarios where unauthenticated remote attackers can gain system-level access to vulnerable Windows systems, potentially leading to complete network compromise. The RPC runtime component is deeply integrated into Windows architecture, making this vulnerability particularly dangerous as it can be leveraged across multiple attack vectors including domain controller exploitation and lateral movement within networks.
The operational impact of CVE-2021-1660 extends far beyond individual system compromise, as it enables attackers to establish persistent access to enterprise environments through the RPC infrastructure that many organizations rely upon for critical operations. Organizations running vulnerable Windows versions including Windows 7, Windows Server 2008, and various Windows Server 2019 releases face significant risk of unauthorized access and data exfiltration. The vulnerability's remote execution capability means that attackers can exploit it from anywhere on the network, making traditional perimeter security measures insufficient for protection. This flaw directly maps to several ATT&CK techniques including T1075 Remote Services, T1046 Network Service Scanning, and T1059 Command and Scripting Interpreter, as it enables attackers to establish persistent backdoors and execute commands on compromised systems. The attack surface is particularly broad since RPC services are enabled by default on most Windows installations and are commonly used for legitimate administrative tasks.
Mitigation strategies for CVE-2021-1660 should include immediate deployment of Microsoft security patches as released in the January 2021 security updates, which address the specific RPC runtime vulnerability through code-level fixes. Organizations should implement network segmentation to limit RPC service exposure and disable unnecessary RPC endpoints where possible. The principle of least privilege should be enforced by restricting RPC access to only necessary systems and users, while also implementing network access controls to prevent unauthorized RPC communication. Additionally, security monitoring should be enhanced to detect anomalous RPC traffic patterns that may indicate exploitation attempts, particularly focusing on unusual authentication requests or large data transfers through RPC ports. Network administrators should also consider implementing intrusion detection systems that can identify potential exploitation attempts through signature-based detection of known malicious RPC request patterns. The vulnerability underscores the importance of maintaining up-to-date security patches and demonstrates how fundamental system components can provide attackers with powerful exploitation capabilities when vulnerable to remote code execution flaws.