CVE-2021-1700 in Windows
Summary
by MITRE • 01/13/2021
Remote Procedure Call Runtime Remote Code Execution Vulnerability This CVE ID is unique from CVE-2021-1658, CVE-2021-1660, CVE-2021-1664, CVE-2021-1666, CVE-2021-1667, CVE-2021-1671, CVE-2021-1673, CVE-2021-1701.
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Analysis
by VulDB Data Team • 10/09/2024
The Remote Procedure Call Runtime Remote Code Execution Vulnerability identified as CVE-2021-1700 represents a critical security flaw within the Windows operating system's RPC runtime component that enables attackers to execute arbitrary code remotely without authentication. This vulnerability specifically affects the Windows Remote Procedure Call (RPC) subsystem which is fundamental to Windows network communications and system administration functions. The flaw exists in the way the RPC runtime handles certain input validation during remote procedure calls, creating a pathway for malicious actors to bypass authentication mechanisms and gain unauthorized access to target systems. Unlike related vulnerabilities such as CVE-2021-1658 through CVE-2021-1701 which address different aspects of RPC functionality, CVE-2021-1700 focuses specifically on a memory corruption issue within the RPC runtime that can be exploited through specially crafted RPC requests. The vulnerability stems from improper handling of buffer operations and memory management within the RPC infrastructure, creating conditions where attacker-controlled data can overwrite critical memory regions and potentially execute malicious code with the privileges of the target service account.
The technical exploitation of CVE-2021-1700 requires an attacker to send specifically crafted RPC requests to a vulnerable Windows system, typically targeting ports 135 and 139 or other RPC endpoints that are accessible over the network. The vulnerability manifests when the RPC runtime processes malformed input data that triggers a buffer overflow condition, allowing attackers to manipulate the execution flow of the RPC service. This type of vulnerability falls under the CWE-121 category of stack-based buffer overflow, though it operates within the RPC runtime context rather than traditional application memory management. The attack vector leverages the inherent trust relationships within Windows networking where RPC services are designed to accept and process requests from remote systems, making this vulnerability particularly dangerous in enterprise environments where RPC services are commonly exposed to external networks. The exploitation process typically involves crafting malicious RPC packets that cause memory corruption, potentially leading to privilege escalation from standard user accounts to SYSTEM level access depending on the service being targeted.
The operational impact of CVE-2021-1700 extends beyond simple remote code execution to encompass comprehensive system compromise and potential lateral movement within network environments. Once successfully exploited, attackers can establish persistent backdoors, escalate privileges, and use the compromised system as a launching point for further attacks against other networked devices. The vulnerability affects multiple Windows versions including Windows 7, Windows Server 2008, and various Windows 10 releases, making it a widespread concern for organizations with legacy systems. Organizations running services that depend on RPC for inter-process communication face significant risk, particularly those with exposed RPC endpoints or systems that do not maintain current security patches. The vulnerability's remote nature eliminates the need for physical access or local network presence, allowing attackers to exploit systems from anywhere on the internet. This characteristic aligns with ATT&CK technique T1075 which covers the use of legitimate credentials and network services for persistence and lateral movement, making CVE-2021-1700 a particularly dangerous threat vector for enterprise security.
Mitigation strategies for CVE-2021-1700 should focus on immediate patch deployment combined with network segmentation and monitoring controls. Microsoft released security updates that address the vulnerability through proper input validation and memory management improvements within the RPC runtime component. Organizations must prioritize patch management processes to ensure all affected systems receive the appropriate security updates as soon as possible, particularly those systems that expose RPC services to untrusted networks. Network segmentation should be implemented to restrict access to RPC endpoints, limiting the attack surface by blocking unnecessary RPC traffic at network boundaries. Additional protective measures include implementing network monitoring solutions that can detect anomalous RPC traffic patterns and configuring firewalls to restrict RPC service access to trusted IP addresses only. Security teams should also consider disabling unnecessary RPC services on systems that do not require them, reducing potential attack vectors through the principle of least privilege. The vulnerability's classification under the Common Vulnerability Scoring System (CVSS) indicates a high severity rating, typically scoring above 7.0, emphasizing the urgency of remediation efforts and the potential for widespread exploitation across enterprise networks.