CVE-2021-28339 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-2021-28340, 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-2021-28339 represents a critical security flaw within Microsoft's RPC runtime environment that enables remote attackers to execute arbitrary code on affected systems. This vulnerability specifically targets the Windows operating system's remote procedure call implementation, which serves as a fundamental communication protocol for distributed applications and system services. The flaw exists in the way the RPC runtime processes incoming requests and handles memory management during remote procedure calls, creating an opportunity for malicious actors to exploit memory corruption issues that could lead to complete system compromise. The vulnerability is particularly concerning because RPC is extensively used across enterprise environments for inter-process communication, making it a prime target for attackers seeking to establish persistent access to networked systems.
The technical exploitation of CVE-2021-28339 occurs through a buffer overflow condition within the RPC runtime components that process remote procedure calls. When a specially crafted RPC request is sent to a vulnerable system, the malformed data causes the RPC runtime to write beyond allocated memory boundaries, potentially allowing an attacker to overwrite critical memory structures or execute malicious code in the context of the target process. This memory corruption vulnerability can be triggered through various RPC endpoints and protocols including DCE-RPC and SMB, making the attack surface particularly broad. The vulnerability's classification as a remote code execution flaw places it under CWE-121, which specifically addresses stack-based buffer overflow conditions, and aligns with ATT&CK technique T1059.007 for Windows Command and Scripting Interpreter, as successful exploitation would enable attackers to execute commands on compromised systems. The vulnerability requires no user interaction for exploitation, making it particularly dangerous in networked environments where systems may be exposed to untrusted network traffic.
The operational impact of CVE-2021-28339 extends far beyond individual system compromise, as successful exploitation can lead to complete network infiltration and persistent access to enterprise environments. Organizations running affected versions of Windows Server and client operating systems face significant risk of unauthorized access to sensitive data, system resources, and network infrastructure. The vulnerability's ability to execute code remotely without authentication means that attackers can potentially compromise systems from outside the network perimeter, especially if RPC services are exposed to external networks. This makes the vulnerability particularly dangerous for organizations with exposed RPC endpoints or those that have not properly configured their firewall rules to restrict RPC traffic. The impact is further amplified by the fact that many enterprise applications rely on RPC for internal communication, potentially allowing attackers to move laterally through network segments once initial access is achieved. Organizations may experience data breaches, system downtime, and potential compliance violations if systems remain unpatched.
Mitigation strategies for CVE-2021-28339 should prioritize immediate patch deployment through Microsoft's security updates, as the vulnerability has been addressed through the Microsoft Security Response Center's patches released in the 2021 February security update cycle. Network administrators should implement firewall rules to restrict RPC traffic between trusted network segments and limit exposure to external networks where possible. The principle of least privilege should be enforced by disabling unnecessary RPC services and endpoints on systems that do not require them. Monitoring for anomalous RPC traffic patterns and unusual authentication attempts can help detect potential exploitation attempts. Organizations should also consider implementing network segmentation strategies to limit the potential lateral movement of attackers who may successfully exploit this vulnerability. The ATT&CK framework suggests implementing defensive measures such as process monitoring, network intrusion detection systems, and endpoint detection and response solutions to identify and prevent exploitation attempts. Regular security assessments and vulnerability scanning should be conducted to ensure that all systems remain protected against this and similar RPC-related vulnerabilities, as the interconnected nature of RPC services means that exploitation of one vulnerable component can potentially affect multiple systems within an organization's infrastructure.