CVE-2021-1701 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-2021-1700.
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Analysis
by VulDB Data Team • 10/09/2024
The CVE-2021-1701 vulnerability represents a critical remote code execution flaw within the Remote Procedure Call (RPC) runtime environment that affects multiple Microsoft Windows operating systems. This vulnerability specifically targets the RPC runtime component responsible for facilitating communication between distributed applications, making it a prime target for attackers seeking to compromise system integrity and execute arbitrary code remotely. The flaw exists in the way the RPC runtime processes incoming requests, creating a potential entry point for malicious actors to gain unauthorized access to affected systems. This vulnerability is particularly concerning because RPC is a fundamental component of Windows networking infrastructure, used extensively in enterprise environments for inter-process communication and distributed application execution.
The technical implementation of this vulnerability stems from improper input validation within the RPC runtime library, specifically when processing malformed or specially crafted RPC requests. Attackers can exploit this weakness by sending malicious RPC messages that trigger buffer overflows or memory corruption conditions within the target system's RPC runtime service. This flaw falls under the CWE-121 category of "Stack-based Buffer Overflow" and aligns with ATT&CK technique T1203 "Exploitation for Client Execution" where adversaries leverage software vulnerabilities to execute code on target systems. The vulnerability affects Windows Server 2008, Windows Server 2012, Windows Server 2016, Windows Server 2019, and Windows 10 operating systems, with the most severe impact occurring on server editions that typically handle more RPC traffic. The exploit requires minimal privileges to succeed and can be executed remotely without user interaction, making it particularly dangerous in networked environments.
The operational impact of CVE-2021-1701 extends beyond simple remote code execution, as successful exploitation can lead to complete system compromise and persistence within the network. Once an attacker gains execution privileges through this vulnerability, they can establish backdoors, escalate privileges to SYSTEM level access, and use the compromised system as a launch point for lateral movement attacks. The vulnerability's characteristics make it particularly attractive to advanced persistent threat actors who seek to maintain long-term access to enterprise networks, as it can be leveraged to create covert communication channels and avoid detection. Organizations running servers that utilize RPC services for legitimate operations face the highest risk, as these systems are often more exposed to external network traffic and may lack the security controls typically found on client systems. The vulnerability's exploitation can result in data exfiltration, system disruption, and complete loss of confidentiality and integrity for affected systems.
Mitigation strategies for CVE-2021-1701 should prioritize immediate patch deployment through Microsoft's regular security updates, as this vulnerability has a CVSS score of 7.8, indicating high severity. Organizations should also implement network segmentation to limit RPC traffic between critical systems and external networks, while monitoring for unusual RPC activity that might indicate exploitation attempts. Additional protective measures include disabling unnecessary RPC services, implementing strict firewall rules that restrict RPC port access, and deploying intrusion detection systems that can identify malicious RPC traffic patterns. The ATT&CK framework recommends implementing process monitoring and endpoint detection capabilities to identify suspicious RPC runtime behavior, while CWE guidelines suggest implementing robust input validation and memory safety controls in all RPC implementations. Security teams should also conduct regular vulnerability assessments to identify systems that may be running outdated RPC components and ensure that all Windows systems receive timely security updates to prevent exploitation of this and similar vulnerabilities.