CVE-2021-28343 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-2021-28336, CVE-2021-28337, CVE-2021-28338, CVE-2021-28339, CVE-2021-28340, CVE-2021-28341, CVE-2021-28342, 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 • 04/16/2021
The Remote Procedure Call Runtime Remote Code Execution Vulnerability identified as CVE-2021-28343 represents a critical security flaw within the Windows operating system's RPC runtime component. This vulnerability specifically affects the way the system processes remote procedure calls, creating an opportunity for malicious actors to execute arbitrary code on affected systems. The flaw resides in the RPC runtime library that facilitates communication between different processes and systems, making it a prime target for attackers seeking to gain unauthorized access to networked environments. The vulnerability is particularly concerning because it can be exploited remotely without requiring any form of authentication, making it accessible to attackers across network boundaries. This characteristic aligns with the Common Weakness Enumeration CWE-121, which categorizes the vulnerability as a buffer overflow condition that allows attackers to execute code in the context of the affected application. The attack surface extends to any system running Windows where RPC services are enabled and accessible, including domain controllers, file servers, and workstations that have not been properly patched. Organizations utilizing Windows Server environments are especially vulnerable since these systems typically have RPC services enabled by default to support various enterprise functions including Active Directory operations and distributed computing tasks.
The technical implementation of this vulnerability involves a specific flaw in how the RPC runtime handles certain input parameters during remote procedure call processing. Attackers can craft malicious RPC requests that trigger memory corruption within the runtime environment, leading to arbitrary code execution. This type of vulnerability typically arises from improper validation of input data or inadequate bounds checking within the RPC processing pipeline. The exploitation mechanism leverages the inherent design of RPC services to establish connections and transmit data, making it particularly challenging to defend against through traditional network segmentation approaches. The vulnerability's impact is amplified by the fact that RPC services are often enabled on systems that might not be directly exposed to external networks, creating internal attack vectors that can be leveraged by compromised insider accounts or lateral movement techniques. According to the MITRE ATT&CK framework, this vulnerability maps to the T1059.007 technique for command and scripting interpreter, as successful exploitation allows attackers to execute commands on the target system. The attack pattern typically involves sending specially crafted RPC messages that cause buffer overflows in memory structures, potentially leading to privilege escalation or complete system compromise.
The operational impact of CVE-2021-28343 extends far beyond individual system compromise, potentially enabling attackers to establish persistent access within enterprise networks. Once exploited, the vulnerability can allow attackers to execute code with the privileges of the RPC service account, which often has elevated permissions depending on the system configuration. This capability creates opportunities for attackers to perform reconnaissance activities, deploy additional malware, or establish backdoors for continued access. The vulnerability's remote exploitability means that attackers can target systems from anywhere on the network, potentially bypassing traditional perimeter security measures such as firewalls and network segmentation. Organizations that have not applied the relevant security patches are particularly at risk since the vulnerability affects multiple Windows versions including Windows 10, Windows Server 2016, and Windows Server 2019. The exploitation of this vulnerability can result in significant business disruption, data breaches, and compliance violations, particularly in environments where sensitive information is processed through RPC services. Security teams must consider the potential for cascading effects where compromise of one system enables lateral movement to other networked systems that may also be vulnerable to similar RPC-related exploits.
Mitigation strategies for CVE-2021-28343 should prioritize immediate patch deployment through Microsoft's security updates, as this represents the most effective defense against exploitation. Organizations should implement network segmentation to limit RPC service exposure and disable unnecessary RPC endpoints to reduce the attack surface. The principle of least privilege should be enforced by ensuring that RPC services operate with minimal required permissions and that only authorized systems can communicate with RPC endpoints. Network monitoring should be enhanced to detect unusual RPC traffic patterns that might indicate exploitation attempts, with particular attention to anomalous connection behaviors and data transfers. Security teams should also consider implementing application whitelisting policies that restrict execution of unsigned code on systems that handle RPC communications. Additional defensive measures include configuring firewalls to block RPC-specific ports where possible, implementing intrusion detection systems that can identify exploitation patterns, and conducting regular vulnerability assessments to identify systems that may be running outdated RPC implementations. The vulnerability's classification under CWE-121 emphasizes the need for robust input validation and memory management practices, which should be reinforced through security awareness training for system administrators and development teams. Organizations should also maintain current threat intelligence feeds to stay informed about exploitation attempts targeting this vulnerability and ensure that their incident response procedures include specific steps for handling RPC-based exploits.