CVE-2020-1013 in Windows
Summary
by MITRE
<p>An elevation of privilege vulnerability exists when Microsoft Windows processes group policy updates. An attacker who successfully exploited this vulnerability could potentially escalate permissions or perform additional privileged actions on the target machine.</p> <p>To exploit this vulnerability, an attacker would need to launch a man-in-the-middle (MiTM) attack against the traffic passing between a domain controller and the target machine. An attacker could then create a group policy to grant administrator rights to a standard user.</p> <p>The security update addresses the vulnerability by enforcing Kerberos authentication for certain calls over LDAP.</p>
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Analysis
by VulDB Data Team • 02/24/2026
This vulnerability represents a critical elevation of privilege flaw in Microsoft Windows systems that specifically manifests during group policy update processing. The weakness stems from insufficient authentication mechanisms when domain controllers communicate with target machines through Lightweight Directory Access Protocol. The vulnerability creates a pathway for attackers to escalate their privileges by manipulating the group policy processing workflow, effectively allowing standard users to gain administrative rights. This issue directly impacts the integrity of Windows domain environments where group policy objects are used to manage security configurations across multiple systems.
The exploitation vector requires a sophisticated man-in-the-middle attack scenario where the adversary intercepts and modifies traffic between domain controllers and target machines. This attack model aligns with the attack technique described in the MITRE ATT&CK framework under T1078 Valid Accounts and T1548.002 Account Manipulation. The attacker must establish a position to intercept LDAP communications and then craft malicious group policy objects that can be applied to target systems. The vulnerability specifically affects the authentication flow during LDAP operations, where the system fails to properly validate the authenticity of requests originating from domain controllers. This weakness creates a trust relationship breach that allows unauthorized privilege escalation without requiring direct system compromise.
The operational impact of this vulnerability extends beyond simple privilege escalation to potentially enable full domain compromise. When an attacker successfully exploits this flaw, they can manipulate group policy settings to grant administrative privileges to accounts they control, effectively gaining persistent access to target systems. This capability enables attackers to establish backdoors, deploy malicious software, and maintain long-term access to network resources. The vulnerability affects Windows domain environments where group policy processing occurs through LDAP connections, making it particularly dangerous in enterprise settings where centralized policy management is common. The attack requires network-level access and the ability to intercept traffic, but once successful, provides a powerful foothold for further compromise.
Microsoft addressed this vulnerability by implementing enhanced Kerberos authentication requirements for specific LDAP calls that occur during group policy processing. This mitigation strategy aligns with the principle of least privilege and strengthens the authentication mechanisms that validate domain controller authenticity. The fix ensures that group policy updates can only be applied when proper Kerberos authentication is established, preventing unauthorized modification of security policies. Organizations should implement this security update immediately and consider additional network security measures such as LDAP traffic encryption and network monitoring to detect potential MiTM attacks. The vulnerability demonstrates the importance of securing authentication flows in enterprise environments and the potential consequences when these mechanisms are insufficiently protected. This remediation approach follows security best practices outlined in the CWE database under category 287 Improper Authentication and reinforces the need for strong authentication protocols in distributed systems.