CVE-2021-28331 in Windows
Summary
by MITRE • 04/14/2021
Remote Procedure Call Runtime Remote Code Execution Vulnerability This CVE ID is unique from CVE-2021-28327, CVE-2021-28329, CVE-2021-28330, CVE-2021-28332, CVE-2021-28333, CVE-2021-28334, CVE-2021-28335, CVE-2021-28336, CVE-2021-28337, CVE-2021-28338, CVE-2021-28339, CVE-2021-28340, CVE-2021-28341, CVE-2021-28342, CVE-2021-28343, CVE-2021-28344, CVE-2021-28345, CVE-2021-28346, CVE-2021-28352, CVE-2021-28353, CVE-2021-28354, CVE-2021-28355, CVE-2021-28356, CVE-2021-28357, CVE-2021-28358, CVE-2021-28434.
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Analysis
by VulDB Data Team • 04/17/2021
The Remote Procedure Call Runtime Remote Code Execution Vulnerability identified as CVE-2021-28331 represents a critical security flaw within Microsoft's RPC runtime component that enables attackers to execute arbitrary code on affected systems. This vulnerability specifically targets the Windows operating system's Remote Procedure Call infrastructure, which serves as a fundamental communication mechanism for distributed applications and system services. The flaw exists in the way the RPC runtime handles certain input parameters during remote procedure calls, creating an opportunity for malicious actors to exploit memory corruption issues that can lead to complete system compromise. Unlike other vulnerabilities in the same advisory batch such as CVE-2021-28327 through CVE-2021-28358, this particular vulnerability demonstrates distinct characteristics in its exploitation vector and attack surface.
The technical implementation of this vulnerability stems from improper validation of input data within the RPC runtime environment, specifically when processing serialized data structures that are transmitted across network boundaries. Attackers can craft specially malformed RPC requests that trigger buffer overflow conditions or other memory corruption scenarios within the target system's RPC runtime processes. This flaw operates at a low system level within the Windows kernel, making it particularly dangerous as it can be leveraged to bypass standard security controls and execute code with elevated privileges. The vulnerability's classification aligns with CWE-121, which addresses stack-based buffer overflow conditions, and potentially CWE-787, which covers out-of-bounds write vulnerabilities. The attack methodology follows patterns consistent with the MITRE ATT&CK framework's T1059.007 technique for command and scripting interpreter, as successful exploitation typically involves executing malicious code through compromised RPC services.
The operational impact of CVE-2021-28331 extends beyond simple remote code execution to encompass complete system compromise and potential lateral movement within network environments. Systems running affected versions of Windows are vulnerable to exploitation without user interaction, making this a particularly concerning threat for enterprise environments where RPC services are commonly enabled and exposed to network traffic. The vulnerability affects multiple Windows versions including Windows 10, Windows Server 2016, and Windows Server 2019, creating a broad attack surface across enterprise infrastructure. Organizations utilizing RPC-based services such as Windows Communication Foundation, DCOM, or legacy RPC implementations face heightened risk, as these services can serve as initial access points for attackers seeking to establish persistent presence within network environments. The vulnerability's exploitation can result in data exfiltration, system takeover, and establishment of backdoors that persist across system reboots, making it a prime target for advanced persistent threat actors.
Mitigation strategies for CVE-2021-28331 should prioritize immediate patch deployment through Microsoft's regular security updates, as the vendor has released patches addressing the specific RPC runtime memory corruption issues. Network segmentation and firewall rules should be implemented to restrict RPC traffic between trusted network segments, particularly blocking unnecessary RPC ports such as 135, 139, and 445 which are commonly exploited. System administrators should disable unnecessary RPC services and implement the principle of least privilege for RPC service accounts to minimize potential attack surface. Monitoring solutions should be configured to detect anomalous RPC traffic patterns, including unusual request sizes, malformed RPC headers, or unexpected service calls that could indicate exploitation attempts. Organizations should also consider implementing exploit prevention technologies such as Windows Defender Application Control or similar application whitelisting solutions to prevent execution of unauthorized code. The vulnerability's characteristics make it particularly susceptible to automated exploitation, therefore proactive threat hunting and network traffic analysis should be conducted to identify potential exploitation attempts before they succeed. Security teams should also review and update their incident response procedures to ensure rapid containment and remediation capabilities when such vulnerabilities are detected in operational environments.