TCP Directory

Port 3269 (AD GC SSL)

Learn about port 3269 (AD GC SSL) - security risks, vulnerabilities, and common uses. Find devices with port 3269 open.

Quick Info

Port Number

3269

Protocol

TCP

Service

AD GC SSL

IANA Name

AD GC SSL

Service Description

TCP port 3269 is commonly associated with the Active Directory Global Catalog (GC) over SSL/TLS. The Global Catalog is a domain controller that contains a partial replica of every object in the forest. This allows applications to perform forest-wide searches without having to query every domain controller in every domain. When using SSL/TLS for secure communication, the GC uses port 3269. The protocol used on this port is LDAP (Lightweight Directory Access Protocol) wrapped in SSL/TLS. Clients connect to a GC server, authenticate (if required), and then issue LDAP queries to search for objects or attributes across the Active Directory forest. The GC server responds with the requested data, which is encrypted in transit thanks to the SSL/TLS layer.

At a technical level, the client initiates a TCP connection to the GC server on port 3269. After the connection is established, an SSL/TLS handshake occurs to negotiate the encryption algorithms and establish a secure channel. Once the secure channel is established, the client can send LDAP requests encoded in ASN.1 BER (Abstract Syntax Notation One, Basic Encoding Rules) format. The GC server processes these requests, queries its local database (which contains the partial replica of the forest), and returns the results, also encoded in ASN.1 BER format, through the secure channel. The client then decrypts the data and presents it to the application. The use of SSL/TLS ensures confidentiality and integrity of the data exchanged between the client and the GC server, protecting sensitive information like user credentials and directory attributes.

## Firewall Recommendations

Port 3269 should generally be open only to internal network segments where clients need to access the Global Catalog. Restricting access to only authorized machines significantly reduces the attack surface. Monitor traffic to and from this port for suspicious activity, such as unusual query patterns or connections from unexpected sources. Ensure that the SSL/TLS configuration is strong, using up-to-date cipher suites and properly configured certificates. Regularly patch the operating system and Active Directory Domain Services to address any known vulnerabilities. If not required for specific applications, consider disabling the Global Catalog functionality on domain controllers that don't need to act as GCs to minimize potential exposure. Implement robust authentication and authorization mechanisms to prevent unauthorized access to the Global Catalog. Consider using intrusion detection/prevention systems (IDS/IPS) to detect and block malicious traffic targeting this port. If external access to Active Directory is required, consider using a VPN instead of directly exposing port 3269 to the internet.

Security Information

While the use of SSL/TLS on port 3269 provides encryption, it doesn't eliminate all security risks. One primary concern is the exposure of the Global Catalog itself. If an attacker gains unauthorized access to a GC server, they can potentially enumerate all objects in the Active Directory forest, gathering valuable information for reconnaissance and further attacks. Weak SSL/TLS configurations, such as using outdated cipher suites or self-signed certificates, can also be exploited. Furthermore, vulnerabilities in the LDAP implementation or the underlying operating system can be leveraged to compromise the GC server. Attackers might target this port for information gathering, privilege escalation, or denial-of-service attacks. Improper access control to the GC can lead to sensitive information disclosure. Also, misconfigured or vulnerable applications querying the GC can inadvertently expose sensitive data or provide an entry point for attackers to exploit vulnerabilities in the application itself.

Known Vulnerabilities

CVE	Name	Severity	Description
CVE-2017-8563	Active Directory Domain Services Elevation of Privilege Vulnerability	High	Уязвимость в службах домена Active Directory, позволяющая злоумышленнику повысить свои привилегии.
CVE-2017-0222	Microsoft Active Directory Federation Services Security Feature Bypass Vulnerability	Medium	Уязвимость обхода функции безопасности в службах федерации Active Directory Microsoft (AD FS)