CVE-2020-1584 in Windows
Summary
by MITRE
An elevation of privilege vulnerability exists in the way that the dnsrslvr.dll handles objects in memory. An attacker who successfully exploited the vulnerability could execute code with elevated permissions. To exploit the vulnerability, a locally authenticated attacker could run a specially crafted application. The security update addresses the vulnerability by ensuring the dnsrslvr.dll properly handles objects in memory.
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Analysis
by VulDB Data Team • 02/24/2026
The vulnerability identified as CVE-2020-1584 represents a critical elevation of privilege flaw within the dnsrslvr.dll component of Microsoft Windows systems. This vulnerability falls under the Common Weakness Enumeration category CWE-121, which specifically addresses stack-based buffer overflow conditions that can lead to arbitrary code execution. The dnsrslvr.dll module serves as a critical component in Windows DNS resolution processes, handling memory objects during domain name resolution operations. When improperly managed, this component creates an exploitable condition where malicious code can be executed with elevated privileges, potentially compromising the entire system.
The technical exploitation of this vulnerability requires a locally authenticated attacker who can execute a specially crafted application on the target system. This attack vector operates through memory corruption techniques that leverage improper handling of objects within the dnsrslvr.dll memory space. The flaw manifests when the DLL processes certain memory structures without adequate validation, allowing an attacker to manipulate memory contents and potentially overwrite critical system functions. The vulnerability demonstrates characteristics consistent with heap-based memory corruption issues, where attacker-controlled data can influence the execution flow of the target process. This type of vulnerability is particularly dangerous because it can be exploited by users who already have local access to the system, making it a significant concern for both enterprise and individual security postures.
The operational impact of CVE-2020-1584 extends beyond simple privilege escalation, as successful exploitation can lead to complete system compromise and persistent access. Attackers can leverage this vulnerability to gain SYSTEM-level privileges, enabling them to install malware, modify system files, access sensitive data, and establish backdoors for continued access. The vulnerability affects multiple Windows versions including Windows 10, Windows Server 2016, and Windows Server 2019, making it a widespread concern across enterprise environments. Organizations running these affected systems face significant risk of lateral movement and data exfiltration if this vulnerability remains unpatched. The attack surface is particularly concerning in environments where local user accounts are prevalent, as the exploitation requires minimal privileges to begin the attack chain.
Microsoft addressed this vulnerability through a security update that corrects the memory handling procedures within dnsrslvr.dll, implementing proper validation and bounds checking for memory objects. The fix ensures that the DLL properly manages memory allocation and deallocation processes, preventing the corruption that enables privilege escalation. Security professionals should prioritize deployment of this update across all affected systems, particularly in high-value enterprise environments where the risk of exploitation is elevated. The mitigation strategy aligns with the MITRE ATT&CK framework's privilege escalation tactics, specifically targeting techniques that involve exploitation of software vulnerabilities. Organizations should also implement additional security controls such as application whitelisting, mandatory access controls, and monitoring for anomalous memory access patterns to further reduce the attack surface and detect potential exploitation attempts.