域渗透-Kerberos协议中spn的应用

0x01 关于SPN

服务主体名称（SPN）是Kerberos客户端用于唯一标识给特定Kerberos目标计算机的服务实例名称。

服务主体名称是服务实例（可以理解为一个服务，比如 HTTP、MSSQL）的唯一标识符。Kerberos 身份验证使用 SPN 将服务实例与服务登录帐户相关联。

在内部网络中，SPN扫描通过 查询向域控制器执行服务发现。这对于红队而言，可以帮助他们识别正在运行重要服务的主机，如终端、交换机、微软SQL等，并隐藏他们。此外，SPN的识别也是kerberoasting攻击的第一步。

0x02 SPN基础配置

详细可以查看微软官方手册

https://docs.microsoft.com/zh-cn/windows-server/networking/sdn/security/kerberos-with-spn

在 SPN 的语法中存在四种元素，两个必须元素和两个额外元素，其中<service class>和<host>为必须元素：

<serviceclass>/<host>:<port>/<service name>

<service class>：标识服务类的字符串

<host>：服务所在主机名称

<port>：服务端口

<service name>：服务名称

常见服务和spn服务实例名称

MSSQL

MSSQLSvc/adsmsSQLAP01.adsecurity.org:1433

Exchange

exchangeMDB/adsmsEXCAS01.adsecurity.org

RDP

TERMSERV/adsmsEXCAS01.adsecurity.org

WSMan / WinRM / PS Remoting

WSMAN/adsmsEXCAS01.adsecurity.org

Hyper-V Host

Microsoft Virtual Console Service/adsmsHV01.adsecurity.org

VMWare VCenter

STS/adsmsVC01.adsecurity.org

 

提一下SPN的注册

这里以SQL Server服务为例子。

SQL Server在每次启动的时候，都会去尝试用自己的启动账号注册SPN。但是在Windows域里，默认普通机器账号有权注册SPN，但是普通域用户账号是没有权利注册SPN的。这就会导致这样一个现象，SQL Server如果使用“Local System account”来启动，Kerberos就能够成功，因为SQL Server这时可以在DC上注册SPN。如果用一个域用户来启动，Kerberos就不能成功，因为这时SPN注册不上去。

 

 

解决的方法之一，当然可以使用工具SetSPN -S来手动注册SPN。但是这不是一个最好的方法，毕竟手工注册不是长久之计。如果SPN下次丢了，又要再次手动注册。所以比较好的方法，是让SQL Server当前的启动账号有注册SPN的权力。要在DC上为域账号赋予“Read servicePrincipalName”和“Write serverPrincipalName”的权限即可。

SetSPN

SetSPN是一个本地windows二进制文件，可用于检索用户帐户和服务之间的映射。该实用程序可以添加，删除或查看SPN注册。

 

这里在我dc上进行SPN服务(MSSQL)的注册。

Setspn -A MSSQLSvc/DC-1.qing.com:1433 tsvc

注册成功之后可以通过下面两个命令来查看已经注册的 SPN。

setspn -Q */*

 setspn -T DC-1.qing.com -Q */*

 注意这里是写机器的FQDN

 

 

0x03 SPN扫描

附上MSSQL的spn扫描脚本

function Discover-PSMSSQLServers
{

<#
.SYNOPSIS
This script is used to discover Microsoft SQL servers without port scanning.
SQL discovery in the Active Directory Forest is performed by querying an Active Directory Gloabl Catalog via ADSI.

Discover-PSMSSQLServers
Author: Sean Metcalf, Twitter: @PyroTek3
License: BSD 3-Clause
Required Dependencies: None
Optional Dependencies: None

Last Updated: 2/04/2015
Version: 2.3

.DESCRIPTION
This script is used to discover Microsoft SQL servers in the Active Directory Forest.

Currently, the script performs the following actions:
    * Queries a Global Catalog in the Active Directory root domain for all Microsoft SQL SPNs in the forest
    * Displays the Microsoft SQL server FQDNs ports and instances
    * Identifies any service accounts associated with the SQL instance and includes the account info 

REQUIRES: Active Directory user authentication. Standard user access is fine - admin access is not necessary.

.EXAMPLE
Discover-PSMSSQLServers
Perform Microsoft SQL Server discovery via AD and returns the results in a custom PowerShell object.

.NOTES
This script is used to discover Microsoft SQL servers in the Active Directory Forest and can also provide additional computer information such as OS and last bootup time.

.LINK
Blog: http://www.ADSecurity.org
Github repo: https://github.com/PyroTek3/PowerShell-AD-Recon


#>

Param
    (

    )

Write-Verbose "Get current Active Directory domain... "
$ADForestInfo = [System.DirectoryServices.ActiveDirectory.Forest]::GetCurrentForest()
$ADForestInfoRootDomain = $ADForestInfo.RootDomain
$ADForestInfoRootDomainDN = "DC=" + $ADForestInfoRootDomain -Replace(".",',DC=')

$ADDomainInfoLGCDN = 'GC://' + $ADForestInfoRootDomainDN

Write-Verbose "Discovering Microsoft SQL Servers in the AD Forest $ADForestInfoRootDomainDN "
$root = [ADSI]$ADDomainInfoLGCDN 
$ADSearcher = new-Object System.DirectoryServices.DirectorySearcher($root,"(serviceprincipalname=mssql*)") 
$ADSearcher.PageSize = 50000
$AllADSQLServerSPNs = $ADSearcher.FindAll() 

$AllADSQLServerSPNsCount = $AllADSQLServerSPNs.Count

Write-Output "Processing $AllADSQLServerSPNsCount (user and computer) accounts with MS SQL SPNs discovered in AD Forest $ADForestInfoRootDomainDN `r "

$AllMSSQLSPNs = $NULL
$AllMSSQLSPNHashTable =@{}
$AllMSSQLServiceAccountHashTable =@{}
ForEach ($AllADSQLServerSPNsItem in $AllADSQLServerSPNs)
    {
        $AllADSQLServerSPNsItemDomainName = $NULL
        [array]$AllADSQLServerSPNsItemArray = $AllADSQLServerSPNsItem.Path -Split(",DC=")
        [int]$DomainNameFECount = 0
        ForEach ($AllADSQLServerSPNsItemArrayItem in $AllADSQLServerSPNsItemArray)
            {
                IF ($DomainNameFECount -gt 0)
                { [string]$AllADSQLServerSPNsItemDomainName += $AllADSQLServerSPNsItemArrayItem + "." }
                $DomainNameFECount++
            }
        $AllADSQLServerSPNsItemDomainName = $AllADSQLServerSPNsItemDomainName.Substring(0,$AllADSQLServerSPNsItemDomainName.Length-1)

        ForEach ($ADSISQLServersItemSPN in $AllADSQLServerSPNsItem.properties.serviceprincipalname)
            {
                IF ( ($ADSISQLServersItemSPN -like "MSSQL*") -AND ($ADSISQLServersItemSPN -like "*:*") )
                    { 
                        IF (($AllADSQLServerSPNsItem.properties.objectcategory -like "CN=Person*") -AND ($ADSISQLServersItemSPNServerFQDN) )
                            {
                                $AllMSSQLServiceAccountHashTable.Set_Item($ADSISQLServersItemSPNServerFQDN,$AllADSQLServerSPNsItem.properties.distinguishedname)
                            }
                        $ADSISQLServersItemSPNArray1 = $ADSISQLServersItemSPN -Split("/")
                        $ADSISQLServersItemSPNArray2 = $ADSISQLServersItemSPNArray1 -Split(":")
                        [string]$ADSISQLServersItemSPNServerFQDN = $ADSISQLServersItemSPNArray2[1]
                        IF ($ADSISQLServersItemSPNServerFQDN -notlike "*$AllADSQLServerSPNsItemDomainName*" )
                            { $ADSISQLServersItemSPNServerFQDN = $ADSISQLServersItemSPNServerFQDN + "." + $AllADSQLServerSPNsItemDomainName }
                        [string]$AllMSSQLSPNsItemServerInstancePort = $ADSISQLServersItemSPNArray2[2]

                        $AllMSSQLSPNsItemServerName = $ADSISQLServersItemSPNServerFQDN -Replace(("."+ $AllADSQLServerSPNsItemDomainName),"")

                        $AllMSSQLSPNHashTableData = $AllMSSQLSPNHashTable.Get_Item($ADSISQLServersItemSPNServerFQDN)
                        IF ( ($AllMSSQLSPNHashTableData) -AND ($AllMSSQLSPNHashTableData -notlike "*$AllMSSQLSPNsItemServerInstancePort*") )
                            {
                                $AllMSSQLSPNHashTableDataUpdate = $AllMSSQLSPNHashTableData + ";" + $AllMSSQLSPNsItemServerInstancePort
                                $AllMSSQLSPNHashTable.Set_Item($ADSISQLServersItemSPNServerFQDN,$AllMSSQLSPNHashTableDataUpdate)  
                            }
                          ELSE 
                            { $AllMSSQLSPNHashTable.Set_Item($ADSISQLServersItemSPNServerFQDN,$AllMSSQLSPNsItemServerInstancePort) }
                    } 
            }
    }

###
Write-Verbose "Loop through the discovered MS SQL SPNs and build the report " 
###
$ALLSQLServerReport = @()
#$AllMSSQLServerFQDNs = $NULL
ForEach ($AllMSSQLSPNsItem in $AllMSSQLSPNHashTable.GetEnumerator())
    {
        $AllMSSQLSPNsItemServerDomainName = $NULL
        $AllMSSQLSPNsItemServerDomainDN = $NULL
        $AllMSSQLSPNsItemServiceAccountDN = $NULL
        $AllMSSQLSPNsItemServiceAccountDomainDN = $NULL

        $AllMSSQLSPNsItemServerFQDN =  $AllMSSQLSPNsItem.Name
        #[array]$AllMSSQLServerFQDNs += $AllMSSQLSPNsItemServerFQDN
        $AllMSSQLSPNsItemInstancePortArray = ($AllMSSQLSPNsItem.Value) -Split(';')

        $AllMSSQLSPNsItemServerFQDNArray = $AllMSSQLSPNsItemServerFQDN -Split('.')
        [int]$FQDNArrayFECount = 0
        ForEach ($AllMSSQLSPNsItemServerFQDNArrayItem in $AllMSSQLSPNsItemServerFQDNArray)
            {
                IF ($FQDNArrayFECount -ge 1)
                    { 
                        [string]$AllMSSQLSPNsItemServerDomainName += $AllMSSQLSPNsItemServerFQDNArrayItem + "." 
                        [string]$AllMSSQLSPNsItemServerDomainDN += "DC=" + $AllMSSQLSPNsItemServerFQDNArrayItem + "," 
                    }
                $FQDNArrayFECount++
            }

        $AllMSSQLSPNsItemServerDomainName = $AllMSSQLSPNsItemServerDomainName.Substring(0,$AllMSSQLSPNsItemServerDomainName.Length-1)
        $AllMSSQLSPNsItemServerDomainDN = $AllMSSQLSPNsItemServerDomainDN.Substring(0,$AllMSSQLSPNsItemServerDomainDN.Length-1)
        $AllMSSQLSPNsItemServerDomainLDAPDN = "LDAP://$AllMSSQLSPNsItemServerDomainDN"

        $AllMSSQLSPNsItemServerName = $AllMSSQLSPNsItemServerFQDN -Replace(("."+$AllMSSQLSPNsItemServerDomainName),"")

        $AllMSSQLSPNsItemServiceAccountDN = $AllMSSQLServiceAccountHashTable.Get_Item($AllMSSQLSPNsItemServerFQDN)
            IF ($AllMSSQLSPNsItemServiceAccountDN)
                {
                    $ADServiceAccountSearchInfo = @()
                    $AllMSSQLSPNsItemServiceAccountDNArray = $AllMSSQLSPNsItemServiceAccountDN -Split(",")
                    ForEach ($AllMSSQLSPNsItemServiceAccountDNArrayItem in $AllMSSQLSPNsItemServiceAccountDNArray)
                        {
                            IF ($AllMSSQLSPNsItemServiceAccountDNArrayItem -like 'DC=*')
                                { [string]$AllMSSQLSPNsItemServiceAccountDomainDN += "$AllMSSQLSPNsItemServiceAccountDNArrayItem," }

                        }
                    $AllMSSQLSPNsItemServiceAccountDomainDN = $AllMSSQLSPNsItemServiceAccountDomainDN.Substring(0,$AllMSSQLSPNsItemServiceAccountDomainDN.Length-1)

                    $AllMSSQLSPNsItemServiceAccountDomainLDAPDN = "LDAP://$AllMSSQLSPNsItemServiceAccountDomainDN"

                    $ADServiceAccountSearch = New-Object DirectoryServices.DirectorySearcher([ADSI]"")
                    $ADServiceAccountSearch.SearchRoot = $AllMSSQLSPNsItemServiceAccountDomainLDAPDN
                    $ADServiceAccountSearch.PageSize = 50000
                    $ADServiceAccountSearch.Filter = "distinguishedname=$AllMSSQLSPNsItemServiceAccountDN"
                    $ADServiceAccountSearchInfo = $ADServiceAccountSearch.FindAll() 
                    
                    IF ($ADServiceAccountSearchInfo)
                        {  
                            [string]$ADServiceAccountSAMAccountName = $ADServiceAccountInfo[0].Properties.samaccountname
                            [string]$ADServiceAccountdescription = $ADServiceAccountSearchInfo[0].Properties.description
                            [string]$ADServiceAccountpwdlastset = $ADServiceAccountSearchInfo[0].Properties.pwdlastset
                             [string]$ADServiceAccountPasswordLastSetDate = [datetime]::FromFileTimeUTC($ADServiceAccountpwdlastset)
                            [string]$ADServiceAccountlastlogon = $ADServiceAccountSearchInfo[0].Properties.lastlogon
                             [string]$ADServiceAccountLastLogonDate = [datetime]::FromFileTimeUTC($ADServiceAccountlastlogon)

                             $ADServiceAccountadmincount = $ADServiceAccountSearchInfo[0].Properties.admincount
                             
                             [string]$ADServiceAccountDistinguishedName = $ADServiceAccountSearchInfo[0].Properties.distinguishedname
                        }
                    $ADServiceAccountLDAPDN = "LDAP://"+$ADServiceAccountDistinguishedName
                     $ADServiceAccountInfo = ([adsi] $ADServiceAccountLDAPDN)
                    
                }
        ForEach ($AllMSSQLSPNsItemInstancePortArrayItem in $AllMSSQLSPNsItemInstancePortArray)
            {
                $AllMSSQLSPNsItemServerPort = $NULL
                $AllMSSQLSPNsItemServerInstance = $NULL

                $SQLServerReport = New-Object -TypeName System.Object 
                $SQLServerReport | Add-Member -MemberType NoteProperty -Name Domain -Value $AllMSSQLSPNsItemServerDomainName
                $SQLServerReport | Add-Member -MemberType NoteProperty -Name ServerName -Value $AllMSSQLSPNsItemServerFQDN

                IF ($AllMSSQLSPNsItemInstancePortArrayItem -match "^[d.]+$")
                    { [int]$AllMSSQLSPNsItemServerPort = $AllMSSQLSPNsItemInstancePortArrayItem }
                IF ($AllMSSQLSPNsItemInstancePortArrayItem -NOTmatch "^[d.]+$")
                    { [string]$AllMSSQLSPNsItemServerInstance = $AllMSSQLSPNsItemInstancePortArrayItem } 
        
                $SQLServerReport | Add-Member -MemberType NoteProperty -Name Port -Value $AllMSSQLSPNsItemServerPort
                $SQLServerReport | Add-Member -MemberType NoteProperty -Name Instance -Value $AllMSSQLSPNsItemServerInstance
                $SQLServerReport | Add-Member -MemberType NoteProperty -Name ServiceAccountDN -Value $AllMSSQLSPNsItemServiceAccountDN

                TRY
                    {
                        $ADComputerSearch = New-Object DirectoryServices.DirectorySearcher([ADSI]"")
                        $ADComputerSearch.SearchRoot = $AllMSSQLSPNsItemServerDomainLDAPDN
                        $ADComputerSearch.PageSize = 50000
                        $ADComputerSearch.Filter = "(&(objectCategory=Computer)(name=$AllMSSQLSPNsItemServerName))"
                        $ADComputerSearchInfo = $ADComputerSearch.FindAll()
                        
                        [string]$ComputerADInfoLastLogonTimestamp = ($ADComputerSearchInfo[0].properties.lastlogontimestamp)
                        TRY { [datetime]$ComputerADInfoLLT = [datetime]::FromFileTime($ComputerADInfoLastLogonTimestamp) }
                            CATCH { }
                        
                        #$ComputerADInfo.Values

                        $SQLServerReport | Add-Member -MemberType NoteProperty -Name OperatingSystem -Value ($ADComputerSearchInfo[0].properties.operatingsystem)
                        $SQLServerReport | Add-Member -MemberType NoteProperty -Name OSServicePack -Value ($ADComputerSearchInfo[0].properties.operatingsystemservicepack)
                        $SQLServerReport | Add-Member -MemberType NoteProperty -Name LastBootup -Value $ComputerADInfoLLT  
                        $SQLServerReport | Add-Member -MemberType NoteProperty -Name OSVersion -Value ($ADComputerSearchInfo[0].properties.operatingsystemversion)
                        $SQLServerReport | Add-Member -MemberType NoteProperty -Name Description -Value ($ADComputerSearchInfo[0].properties.description)
                    }
                  CATCH { } 

                IF ($AllMSSQLSPNsItemServiceAccountDN)
                    {
                        $SQLServerReport | Add-Member -MemberType NoteProperty -Name SrvAcctUserID -Value $ADServiceAccountSAMAccountName
                        $SQLServerReport | Add-Member -MemberType NoteProperty -Name SrvAcctDescription -Value $ADServiceAccountdescription
                        #$SQLServerReport | Add-Member -MemberType NoteProperty -Name SrvAcctPasswordLastSet -Value $ADServiceAccountPasswordLastSetDate
                        #$SQLServerReport | Add-Member -MemberType NoteProperty -Name SAadmincount -Value $ADServiceAccountadmincount
                    }

                [array]$ALLSQLServerReport += $SQLServerReport
            }
    } 

# Find all SQL service account that may be a domain-level admin in the domain
# $ALLSQLServerReport | Where {$_.SAadmincount -eq 1} | select ServerName,SrvAcctUserID,SrvAcctPasswordLastSet,SrvAcctDescription | sort SrvAcctUserID -unique | format-table -auto
return $ALLSQLServerReport

} 

下面列出常见spn扫描工具:

由于每台服务器都需要注册用于Kerberos身份验证服务的SPN，因此这为在不进行端口扫描的情况下收集有关环境的信息提供了一个完美的方法。

PowerShell-AD-Recon

除了Tim Medin开发的工具外，Sean Metcalf也开发了各种PowerShell脚本来执行Kerberos侦察。这些脚本是PowerShell AD Recon存储库的一部分，可以在Active Directory中查询服务，例如Exchange，Microsoft SQL，Terminal等。Sean将每个脚本绑定到一个特定的服务，具体取决于你想要发现的SPN。以下脚本将标识网络上的所有Microsoft SQL实例。

 参考

http://en.hackdig.com/?17699.htm

GetUserSPNs：

GetUserSPNs 是 Kerberoast 工具集中的一个 powershell 脚本，用来查询域内注册的 SPN。

查看当前 域 qing.com的spn

PowerView：

PowerView 是由 Will Schroeder（https://twitter.com/harmj0y）开发的 Powershell 脚本，在 Powersploit 和 Empire 工具里都有集成，PowerView 相对于上面几种是根据不同用户的 objectsid 来返回，返回的信息更加详细。

查看当前 域 qing.com的spn

 

 暂时写到这里，有空后面补充