CVE-2021-1666 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-2021-1667, CVE-2021-1671, CVE-2021-1673, CVE-2021-1700, CVE-2021-1701.
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Analysis
by VulDB Data Team • 10/09/2024
The CVE-2021-1666 vulnerability represents a critical remote code execution flaw within the Remote Procedure Call runtime environment that affects multiple Microsoft Windows operating systems. This vulnerability stems from improper handling of certain RPC protocol operations that can be exploited by remote attackers to execute arbitrary code on affected systems. The flaw exists in the way the RPC runtime processes incoming requests and validates parameters, creating a pathway for malicious actors to gain unauthorized access and potentially establish persistent control over target machines. Security researchers have identified this issue as particularly dangerous due to its remote exploitability and the broad impact across various Windows versions including server and desktop operating systems.
The technical implementation of this vulnerability involves a buffer over-read condition that occurs when the RPC runtime processes malformed or specially crafted RPC requests. When an attacker sends a malicious RPC message with improperly formatted data structures, the system's memory management routines fail to properly validate input boundaries, leading to memory corruption that can be leveraged to redirect execution flow. This type of vulnerability falls under the CWE-125 weakness category, which specifically addresses out-of-bounds read conditions that can result in information disclosure, system crashes, or code execution. The flaw is particularly concerning because it operates at the core networking layer of Windows systems, making it accessible to attackers without requiring local system access or authentication credentials.
The operational impact of CVE-2021-1666 extends far beyond simple remote code execution, as it provides attackers with the capability to perform extensive system compromise activities. Once successfully exploited, the vulnerability allows malicious actors to execute commands with the privileges of the affected service account, potentially leading to full system compromise and lateral movement within network environments. Attackers can leverage this vulnerability to install backdoors, exfiltrate sensitive data, deploy additional malware, or use the compromised systems as launching points for further attacks against other network resources. The vulnerability's remote nature means that attackers can exploit it from anywhere on the internet without requiring physical access to target systems, making it particularly attractive for large-scale automated attacks.
Organizations facing this vulnerability should implement immediate mitigations including applying the relevant Microsoft security patches as soon as they become available. The recommended approach involves deploying the Windows Update patches that address the RPC runtime flaws and implementing network segmentation measures to limit the attack surface. Security teams should also configure firewalls to restrict RPC traffic to necessary systems only and monitor network logs for unusual RPC activity that might indicate exploitation attempts. According to the MITRE ATT&CK framework, this vulnerability maps to the T1059 technique for command and script interpreter, as well as T1071 for application layer protocol usage, making it a significant concern for organizations that rely on RPC-based services for internal communications and system management. Additionally, implementing proper network monitoring and endpoint detection capabilities can help identify potential exploitation attempts before they result in successful compromises.