Windows Server 2019 domain controllers must require LDAP access signing.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-205820	SRG-OS-000423-GPOS-00187	WN19-DC-000320	SV-205820r958908_rule	2025-02-25	3

Description
Unsigned network traffic is susceptible to man-in-the-middle attacks, where an intruder captures packets between the server and the client and modifies them before forwarding them to the client. In the case of an LDAP server, this means that an attacker could cause a client to make decisions based on false records from the LDAP directory. The risk of an attacker pulling this off can be decreased by implementing strong physical security measures to protect the network infrastructure. Furthermore, implementing Internet Protocol security (IPsec) authentication header mode (AH), which performs mutual authentication and packet integrity for Internet Protocol (IP) traffic, can make all types of man-in-the-middle attacks extremely difficult. Satisfies: SRG-OS-000423-GPOS-00187, SRG-OS-000424-GPOS-00188

Description

Unsigned network traffic is susceptible to man-in-the-middle attacks, where an intruder captures packets between the server and the client and modifies them before forwarding them to the client. In the case of an LDAP server, this means that an attacker could cause a client to make decisions based on false records from the LDAP directory. The risk of an attacker pulling this off can be decreased by implementing strong physical security measures to protect the network infrastructure. Furthermore, implementing Internet Protocol security (IPsec) authentication header mode (AH), which performs mutual authentication and packet integrity for Internet Protocol (IP) traffic, can make all types of man-in-the-middle attacks extremely difficult. Satisfies: SRG-OS-000423-GPOS-00187, SRG-OS-000424-GPOS-00188

ℹ️ Check
This applies to domain controllers. It is NA for other systems. If the following registry value does not exist or is not configured as specified, this is a finding: Registry Hive: HKEY_LOCAL_MACHINE Registry Path: \SYSTEM\CurrentControlSet\Services\NTDS\Parameters\ Value Name: LDAPServerIntegrity Value Type: REG_DWORD Value: 0x00000002 (2)

✔️ Fix
Configure the policy value for Computer Configuration >> Windows Settings >> Security Settings >> Local Policies >> Security Options >> "Domain controller: LDAP server signing requirements" to "Require signing".