CVE-2021-28336 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-2021-28331, CVE-2021-28332, CVE-2021-28333, CVE-2021-28334, CVE-2021-28335, 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-2021-28336 represents a critical security flaw within Microsoft's RPC runtime component that enables unauthorized remote code execution on affected systems. This vulnerability specifically impacts Windows operating systems and is distinct from several other related CVEs in the same vulnerability family, emphasizing its unique characteristics within the broader security landscape. The flaw exists in the way the RPC runtime handles certain communication protocols and data processing, creating an avenue for malicious actors to execute arbitrary code on target systems without proper authentication. This vulnerability falls under the CWE-121 category of Buffer Overflow, specifically manifesting as a heap-based buffer overflow that occurs during RPC message processing, making it particularly dangerous for enterprise environments where RPC services are commonly deployed.
The technical exploitation of CVE-2021-28336 requires an attacker to send specially crafted RPC messages to a vulnerable system, which then triggers the buffer overflow condition in the RPC runtime library. When the system processes these malformed messages, the overflow allows attackers to overwrite critical memory locations and potentially execute malicious code with the privileges of the target service account. The vulnerability is particularly concerning because RPC services are fundamental to Windows networking and are often enabled by default on many enterprise systems, providing attackers with multiple potential attack vectors. The flaw can be exploited through various RPC protocols including DCE-RPC and MSRPC, which are used extensively for Windows services, Active Directory operations, and distributed application communication. According to ATT&CK framework, this vulnerability maps to T1203 - Exploitation for Client Execution and T1059 - Command and Scripting Interpreter, as attackers can leverage it to establish persistent access and execute commands on compromised systems.
The operational impact of CVE-2021-28336 extends far beyond individual system compromise, as it can facilitate widespread network infiltration and lateral movement within enterprise environments. Organizations running vulnerable RPC services face significant risk of complete system compromise, data exfiltration, and potential domain controller takeover when this vulnerability is exploited. The vulnerability's remote nature means that attackers can exploit it from external networks without requiring local access, making it particularly dangerous for organizations with exposed RPC services. Security teams must consider the cascading effects of such exploitation, as compromised systems can serve as launching points for further attacks, potentially leading to complete network compromise. The vulnerability affects multiple Windows versions including Windows 10, Windows Server 2016, and Windows Server 2019, making it a widespread concern across enterprise environments. Organizations with complex network infrastructures that rely heavily on RPC communication for business operations face the highest risk of significant operational disruption when this vulnerability is exploited.
Mitigation strategies for CVE-2021-28336 should prioritize immediate patch deployment through Microsoft's regular security updates, as this represents the most effective defense against the vulnerability. System administrators should also implement network segmentation and firewall rules to restrict RPC communication to only necessary systems and ports, reducing the attack surface for potential exploitation. The implementation of network monitoring solutions that can detect unusual RPC traffic patterns and malformed message processing can provide early warning of potential exploitation attempts. Organizations should conduct comprehensive vulnerability assessments to identify all systems running RPC services and ensure proper patch management procedures are in place. Additional defensive measures include disabling unnecessary RPC services, implementing strict access controls for RPC endpoints, and monitoring for suspicious authentication attempts or unusual system behavior that might indicate exploitation attempts. Security teams should also consider implementing intrusion detection systems specifically configured to detect the signature patterns associated with this vulnerability, as well as establishing incident response procedures that account for potential RPC-based attacks. The vulnerability's classification as a remote code execution flaw means that organizations must treat it with the highest priority in their vulnerability management programs, as it can lead to complete system compromise and data breaches without proper defensive measures.