Why It's Open

Port 3269 is used for Microsoft Active Directory Global Catalog over SSL/TLS (LDAP-GC-SSL). This secure service provides a centralized directory of all objects in a multi-domain Active Directory forest, enabling cross-domain object queries and authentication. Organizations rely on this port for secure domain operations including user authentication, resource location, and directory searches across complex enterprise environments. Unlike its unencrypted counterpart on port 3268, traffic on port 3269 is encrypted to protect sensitive directory information during transmission, making it essential for secure enterprise network operations.

Common Risks

Kerberos vulnerabilities
Authentication protocol weaknesses leading to credential theft or forgery
LDAP injection
Malformed queries allowing manipulation of directory data or access controls
SSL/TLS misconfigurations
Outdated cipher suites or protocols enabling traffic interception
Directory information leakage
Excessive object attributes exposed through improper access controls
Authentication bypass
Security flaws allowing unauthorized access to directory services
Certificate validation issues
Improper validation enabling man-in-the-middle attacks
Privilege escalation
Exploitation of directory service flaws to gain elevated permissions
Forest trust vulnerabilities
Trust relationship exploitation between AD domains

__CTA_DEMO__

Enumeration & Testing

Service Detection:

nmap -sV -p 3269 --script ldap-search <target>

SSL/TLS Analysis:

sslscan <target>:3269

Anonymous LDAP Binding Test:

ldapsearch -H ldaps://<target>:3269 -x -s base namingContexts

User Enumeration:

ldapsearch -H ldaps://<target>:3269 -x -D "CN=user,DC=domain,DC=com" -w "password" -b "DC=domain,DC=com" "(objectClass=user)"

Global Catalog Query:

ldapsearch -H ldaps://<target>:3269 -x -D "CN=user,DC=domain,DC=com" -w "password" -b "DC=domain,DC=com" -s sub "(objectclass=*)" "*"

Check Cipher Suites:

nmap --script ssl-enum-ciphers -p 3269 <target>

What to Look For

Checkpoint	What it means
Domain controller version	Identify Windows Server version and patch level for known vulnerabilities
Anonymous binding	Check if unauthenticated access to directory objects is possible
SSL/TLS version	Verify if secure versions (TLS 1.2+) are enforced and weak ciphers disabled
LDAP signing	Confirm if message signing is required to prevent MITM attacks
Certificate validation	Check for expired, self-signed, or improperly validated certificates
Excessive attribute disclosure	Identify if sensitive user/computer attributes are visible to regular users
Kerberos security settings	Evaluate Kerberos configuration for known attack vectors (e.g., Kerberoasting)
Forest trust configurations	Review trust relationships between domains that might be exploitable

Mitigation

Keep domain controllers updated
Apply latest security patches and updates
Enforce LDAPS only
Disable plain LDAP and require SSL/TLS
Implement TLS 1.2+ only
Disable older protocols and weak ciphers
Require LDAP signing
Prevent man-in-the-middle attacks
Use proper certificate management
Implement internal PKI with strong validation
Enforce strong password policies
Enable MFA for privileged accounts
Implement network segmentation
Limit Global Catalog access to required systems
Use Group Policy hardening
Protect domain controllers against common attacks
Restrict sensitive attributes
Implement proper directory ACLs
Audit directory access
Monitor changes to security-sensitive objects

TL;DR

Port 3269 = Microsoft Global Catalog service over SSL
Critical directory service containing domain object information
High-value target for reconnaissance and credential harvesting
Requires secure TLS configuration and strict access controls
Authentication bypass and LDAP injection are common attack vectors

Known CVEs and Exploits

CVE-2019-1040 – A vulnerability in Microsoft Windows that allowed bypassing LDAP signing requirements, enabling credential theft via man-in-the-middle attacks on LDAPS.
CVE-2020-0665 – Active Directory forest trust vulnerability where misconfigured delegation allowed attackers to impersonate users and gain unauthorized access across domains.
CVE-2022-26923 – A certificate privilege escalation vulnerability in Active Directory Certificate Services (AD CS), allowing domain compromise through certificate template abuse, impacting LDAP-based authentication flows.
CVE-2022-29130 – LDAP Remote Code Execution vulnerability in Microsoft Windows when processing specially crafted requests; affected unpatched domain controllers using insecure MaxReceiveBuffer settings.
CVE-2022-22012 – Another critical LDAP RCE affecting domain controllers with misconfigured buffer sizes; allowed unauthenticated attackers to execute code via LDAPS or LDAP requests.

Port 23 – Telnet