CVE-2021-28340 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-2021-28341, 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 CVE-2021-28340 vulnerability represents a critical remote code execution flaw within the Remote Procedure Call runtime environment that affects Microsoft Windows systems. This vulnerability specifically targets the RPC runtime component responsible for facilitating communication between different processes and systems across network boundaries. The flaw exists in how the RPC runtime handles certain input validation processes, creating an opportunity for malicious actors to execute arbitrary code on affected systems without requiring authentication. The vulnerability is particularly concerning because it operates at a foundational layer of Windows networking infrastructure, making it a prime target for sophisticated attack campaigns that aim to establish persistent access or escalate privileges within compromised environments.
The technical implementation of this vulnerability stems from improper validation of remote procedure call parameters within the Windows RPC runtime library. When a malicious actor sends specially crafted RPC requests to a vulnerable system, the runtime fails to properly sanitize input data, leading to memory corruption that can be exploited to execute malicious code with the privileges of the target process. This type of vulnerability typically falls under the Common Weakness Enumeration category CWE-121, which describes heap-based buffer overflow conditions that occur when a program writes data beyond the boundaries of a heap-allocated buffer. The vulnerability is particularly dangerous because it can be triggered remotely without requiring any form of user interaction or authentication, making it an ideal candidate for automated exploitation campaigns.
From an operational perspective, the impact of CVE-2021-28340 extends far beyond simple remote code execution capabilities. The vulnerability can serve as a gateway for attackers to establish persistent backdoors, deploy additional malware payloads, or move laterally through network infrastructure. Security analysts have observed that this vulnerability is often leveraged as part of broader attack chains, where it serves as an initial compromise vector before attackers deploy more sophisticated tools such as remote access trojans or credential harvesting utilities. The vulnerability affects multiple Windows versions including Windows 7, Windows 8.1, Windows Server 2008 R2, and Windows Server 2012, making it particularly widespread across enterprise environments where legacy systems remain operational.
The exploitation of this vulnerability aligns with several tactics described in the MITRE ATT&CK framework, particularly those related to initial access and privilege escalation. Attackers often utilize this vulnerability as part of reconnaissance phases to gain a foothold in target networks, then employ techniques such as process injection or service manipulation to maintain persistence. Organizations that have not applied the relevant security patches are at significant risk of experiencing unauthorized access, data exfiltration, or system compromise. The vulnerability's classification as a remote code execution flaw places it within the high-risk category of cybersecurity threats that require immediate attention and remediation to prevent potential breaches. Network security teams should implement monitoring solutions that can detect anomalous RPC traffic patterns and consider deploying network segmentation strategies to limit the potential impact of successful exploitation attempts.
Mitigation strategies for CVE-2021-28340 should include immediate deployment of Microsoft security patches, which address the underlying validation flaws in the RPC runtime component. Organizations should also implement network-level controls such as firewall rules that restrict RPC traffic to only necessary systems and ports, while maintaining comprehensive logging of RPC activities for security monitoring purposes. Regular vulnerability assessments and penetration testing should be conducted to identify systems that may still be vulnerable despite patching efforts. Additionally, implementing principle of least privilege controls and maintaining up-to-date security information and event management systems will help organizations detect and respond to exploitation attempts more effectively. The vulnerability serves as a reminder of the importance of maintaining current security patches and implementing robust network security controls to protect against sophisticated remote exploitation techniques.