harmj0y kerberoasting

harmj0y kerberoasting

What I mean is, say there are 100 hosts I am interested in getting access on in a domain of tens of thousands of machines. + FullyQualifiedErrorId : ConstructorInvokedThrowException,Microsoft.PowerShell.Commands.NewObjectCommand. Using built-in Windows functionality on a domain-joined host (like the, class) to request tickets which are then extracted from the current logon session with. A Wireshark capture confirms that RC4 is the only supported etype in the request, and that the ticket enc-part is indeed encrypted with RC4. The next graphic shows the results of the PowerShell script code being run. But as I mentioned in the first section, this method requests that highest supported encryption type when requesting a service ticket. This attack is effective since people tend to create poor passwords. Surprisingly hashcat recognized the hash as Kerberos 5 TGS-REP etype 23, finished its run without any errors, but did not recover the password from it. Mimikatz is very popular for dumping user credentials inside an active directory environment, however it can also be used to dump a TGT from LSASS memory. However someone else I asked to recreate wasnt able to, so Im not sure if Im missing something or if this accurately reflects normal domain behavior. The /spn:X argument roasts just the specified SPN, the /user:X argument roasts just the specified user, and the /ou:X argument roasts just users in the specific OU. The Windows implementation of the Kerberos protocol uses service principal names (SPNs) to determine which service account hash to use to encrypt the service ticket. As a reference, in the README I built a table comparing the different Rubeus Kerberoasting approaches: As a final note, Kerberoasting should work much better over domain trusts as of this commit. There have also been times in the field where the default KerberosRequestorSecurityToken Kerberoasting method has just failed- were hoping that the /tgtdeleg option may work in some of these situations. @machosec realized that .NET class KerberosRequestorSecurityToken used in previous approaches also had a GetRequest()method, which returns the raw byte stream of the Kerberos service ticket. to not require Kerberos preauthentication, Then it dawned on me: why not execute this with normal, instead, taking advantage of existing John the Ripper and Hashcat cracking modules. With a bit string manipulation, Matan was able to easily extract out the encrypted (i.e. If the SPN is MSSQLSvc/adsmsDB01.adsecurity.org:1433, then MSSQLSvc is the SPN type. Forest is an easy HackTheBox virtual machine acting as a Windows Domain Controller (DC) in which Exchange Server has been installed. Inter-forest Kerberos tickets also use RC4 unless configured for AES ensure your forest trusts support AES and then enable AES over the trust. Sidenote: the msDS-SupportedEncryptionTypes property can also be set for trustedDomain objects that represent domain trusts, but it is also initially undefined. This means that even if you enable AES encryption for user accounts with servicePrincipalName fields set, these accounts are still Kerberoastable with the hacker-friendly RC4 flavor of encryption keys! However the enc-part part we care about for Kerberoasting (contained within the returned service ticket) is encrypted with the RC4 key of the, It turns out that this has nothing to do with the. We can check the ADSecurity.org SPN directory and see its for Microsoft SQL Server. As stated previously, for a long time I thought the KerberosRequestorSecurityToken approach for some reason specifically requested RC4. Kerberoasting is an attack that was discovered by Tim Medin in 2014, it allows a normal user in a Microsoft Windows Active Directory environment to be able to retrieve the hash for a service account in the same Active Directory environment. During this request process, the attacker can specify what Kerberos encryption types they support (RC4_HMAC, AES256_CTS_HMAC_SHA1_96, etc). Also look for Kerberos DES encryption since this is not secure. Anyone can perform SPN Scanning in order to identify Kerberos service SPNs registered in an Active Directory forest. Using the information regarding ticket encryption type and ticket options, we can use PowerShell to parse the DCs event log looking for 4769 events with this info. Seems like maybe youre reusing some variables from identity to identity where if an operation on an identity fails the script still outputs an object but it just contains the SPN/Hash of the last identity that succeeded. Kerberos AD Attacks - Kerberoasting - XPN InfoSec Blog When I first was looking at this, I assumed that this meant that since the msDS-SupportedEncryptionTypes value was non-null, and the RC4 bit was NOT present, that if you specify only RC4 when requesting a service ticket (via the /tgtdeleg flag here) for an account configured this way the exchange would error out. method can be used to carve out the service ticket bytes from KerberosRequestorSecurityToken, meaning we can forgo Mimikatz for ticket extraction. However someone else I asked to recreate wasnt able to, so Im not sure if Im missing something or if this accurately reflects normal domain behavior. We can request a service ticket for this SPN with. This article will refer to public information and combine my own understanding to introduce the principle and implementation of Kerberoasting, as well as a method of backdoor utilization, and finally give defense suggestions. The Domain Controller doesnt track if the user ever actually connects to these resources (or even if the user has access), so a user can request hundreds of service tickets, even if they never actually connect to the service. Kerberos credential, see inner exception for details. Filter out requests for service names with a $ which are typically for computer accounts (or trusts or Managed Service Accounts, all accounts where Windows automatically generates a long, complex password). With no other arguments, all user accounts with SPNs set in the current domain are Kerberoasted, requesting their highest supported encryption type (see the opsec table). Save my name, email, and website in this browser for the next time I comment. the default value for this field is 0x1C (RC4_HMAC_MD5 | AES128_CTS_HMAC_SHA1_96 | AES256_CTS_HMAC_SHA1_96 = 28) for, . To reiterate, any domain user account that has a service principal name set can have a TGS for that SPN requested by any user in the domain, allowing for the offline cracking of the service account plaintext password! Furthermore, most service accounts are over-permissioned and are often members of Domain Admins providing full admin rights to Active Directory (even when the service account only needs to modify an attribute on certain object types or admin rights on specific servers). Much of this post wont make complete sense if you dont have a base understanding of how Kerberoasting (or Kerberos) works under the hood, so I highly recommend reading up a bit if youre not comfortable with the concepts. This is a short followup demonstrating a technique that dawned on me after posting about decrypting AS-REPs earlier this week. AS-REP Roasting dumps the krbasrep5 hashes of user accounts that have Kerberos pre-authentication disabled. Before having a chance to detect Kerberoasting, its important to have the appropriate logging enabled. Rubeus is a C# Kerberos abuse toolkit that started as a port of @gentilkiwi's Kekeo toolset and has continued to evolve since then. Remember that just requesting this ticket doesnt grant access to the requesting user, as its up to the server/service to ultimately determine whether the user should be given access. With a strong password, the hashes will take longer to crack making this attack less effective. Because of how Kerberos works, any user can request a TGS for any service that has a registered SPN (HOST or arbitrary) in a user or computer account in Active Directory. What is a Kerberoasting Attack? - CrowdStrike Two foreign trusted domain examples have been added to the, As always, if I made some mistake in this post, let me know and Ill correct it as soon as I can! Note the addition of KerberosRequestorSecurityToken which is the PowerShell method to request Kerberos tickets. Kerberos Overview & Communication Process. Domain Admin) rights, you can always downgrade a user to reversible encryption and then DCSync their plaintext password, so this approach is only really useful in cases where you encounter these type of rights before youre able to elevate on the domain itself. A silver ticket can sometimes be better used in engagements rather than a golden ticket because it is a little more discreet. Enabling this audit category on Domain Controllers will result in two interesting event ids being logged: When a domain user requests access to \\WINDOWS1.testlab.local\C$, the KDC maps this request to the HOST/WINDOWS1.testlab.local SPN, indicating that the WINDOWS1$ machine account NTLM hash (which is stored both on WINDOWS1 locally and the NTDS.dit Active Directory database on the DC/KDC) should be used to encrypt the server part of the service ticket. Filter out requests from service accounts (ads45service@lab.adsecurity.org). Note: This attack will not be successful when targeting services hosted by the Windows system since these services are mapped to the computer account in Active Directory which has an associated 128 character password which wont be cracked anytime soon. Warning: A skeleton key only works using Kerberos RC4 encryption. This is why service tickets for machines nearly always use AES256, as the highest mutually supported encryption type will be used in a Kerberos ticket exchange. Configuring system-wide transcription to send a log of all activity per user, per system to a write-only share, is incredibly valuable to catch suspicious/malicious activity that can be missed or not logged to the event logs. This enables an attacker with access to a computer on the network to identify all service accounts supporting Kerberos authentication and what they are used for. Since the service ticket was encrypted with the hash of the account linked to the requested SPN, the attacker can crack this encrypted blob offline to recover the accounts plaintext password. Copyright 2023 harmj0y | Designed by Felicity Brigham Design, This is a short followup demonstrating a technique that, , and I are currently working Active Directory ACL integration for BloodHound. As modern domains (functional level 2008 and above) and computers (Vista/2008+) support using AES keys by default in Kerberos exchanges, the use of RC4 in any Kerberos ticket-granting-ticket (TGT) requests or service ticket requests, that covers how to approach DC events to detect this type of behavior, though as he notes , To illustrate, lets say we have a user account, registered in its servicePrincipalName (SPN) property. The most effective mitigation of this attack is ensuring service account passwords are longer than 25 characters (and arent easily guessable) Targeted Kerberoasting (Harmj0y) Kerberoasting without Mimikatz (Harmj0y) Roasting AS REPs (Harmj0y) Sean Metcalf's Presentations on Active Directory Security; Kerberoast (GitHub) Tim Medin's DerbyCon "Attacking Microsoft Kerberos Kicking the Guard Dog of Hades" presentation in 2014 (slides & video). massive numbers of service tickets in a users logon session). As mentioned previously, @_wald0, @cptjesus, and I are currently working Active Directory ACL integration for BloodHound. massive numbers of service tickets in a users logon session). Hopefully this cleared up some of the confusion some (like me) may have had surrounding different encryption support in regards to Kerberoasting. When a TGS is issued, a timestamp + password hash for the service account is used to encrypt the TGS since the password is the shared secret between the service account and the KDC/DC. What is Kerberoasting? One common example is a service account that manages several MSSQL instances; this user account would have a SPN for each MSSQL instance its registered forstored in the usersserviceprincipalname attribute (Sean keepsan updated list of SPNs here). I recently rolled the necessary functions into a single, that contains the necessary components from PowerView (this has also, ). Also, if anyone has insight on the RC4-tickets-still-being-issued-for-AES-only-accounts situation, please shoot me an email (. And the best part is that everything needed is already implemented in PowerView with Set-DomainObject and Get-DomainSPNTicket! Given modification rights on a target, we can change the users serviceprincipalname to, SPN we want (even something fake), Kerberoast the service ticket, and then repair the serviceprincipalname value. Thanks to the previously work done by @harmj0y to help me get clear picture of Kerberoasting . There are two types of service principal names in Active Directory: host-based SPNs that are linked to a domain, account and arbitrary SPNs that are usually (but not always) linked to a domain, When a new computer account is created in Active Directory, host-based SPNs are automatically generated for built-in servicesIn reality, SPNs are only created for the HOST service and all built-in services use the HOST SPN, The HOST service represents the host computer. This attack is. Impacket v0.9.22 - Copyright 2020 SecureAuth Corporation Even better is ingesting these transcript text files into something like Splunk for further analysis. Targeted Kerberoasting. For conciseness Im going to refer to these as, A standalone implementation of the Kerberos protocol thats used through a device connected on a network, or via piping the crafted traffic in through a SOCKS proxy. This means that even if you enable AES encryption for user accounts with servicePrincipalName fields set, these accounts are still Kerberoastable with the hacker-friendly RC4 flavor of encryption keys! For example in one instance the same SPN/hash is listed for 13 different accounts. And finally, Matan Hart (, , which returns the raw byte stream of the Kerberos service ticket. Penetration Testing Lab. In the example below, we use the previously retrieved Kerberos ticket to connect to DC01 using Impacket 's smbclient.py script. August 31, 2017 TL;DR There are a lot of great blogs out there that show you how to Kerberoast. Save my name, email, and website in this browser for the next time I comment. Kerberos brute-force has a lot of advantages for brute-forcing vs other protocols. ServicePrincipalName Name MemberOf PasswordLastSet LastLogon Delegation One defensive indicator weve talked about in the past is encryption downgrade activity. STS: VMWare SSO service which could provide backdoor VMWare access. This was really a watershed for us, as it greatly expanded the range of service account passwords we could crack. The ticket is sent back to the attacker in a service ticket reply (TGS-REP). We are now no longer dependent on Mimikatz for ticket extraction! You do need to reverse any collected hashes but it's well worth attempting the process because service accounts are commonly part of the domain administrative (DA), enterprise administrative (EA . According toMS-KILE 3.1.1.5 the default value for this field is 0x1C (RC4_HMAC_MD5 | AES128_CTS_HMAC_SHA1_96 | AES256_CTS_HMAC_SHA1_96 = 28) forWindows 7+ and Server 2008R2+. Attackers are most interested in Service Accounts that are members of highly privileged groups like Domain Admins. The retrieved Kerberos ticket is encrypted with the hash of the service account . Other tools such as Impackets GetNPUsers.py can be used for AS-REP Roasting. If we want to utilize the users access, we could force a password reset, but this is fairly destructive in that the target user would notice. Is there a way to enumerate service accounts viable for those 100 hosts, only, or do I have to always enumerate all service accounts over the entire (humongous) domain? At C:\tools\Invoke-Kerberoast.ps1:555 char:23 Event ID 4769 will be logged many, many times in the domain since after initial logon (and Kerberos TGT ticket request), users request Kerberos TGS service tickets to access the may services on the network (file shares, SQL, SharePoint, etc). Put another way, The HOST service represents the host computer. The reason why this attack is successful is that most service account passwords are the same length as the domain password minimum (often 10 or 12 characters long) meaning that even brute force cracking doesnt likely take longer than the password maximum password age (expiration). Unlike Kerberoasting these users do not have to be service accounts the only requirement to be AS-REP roastable is to have the privilege Does not require Pre-Authentication set. Kerberoasting allows a user to request a service ticket for any service with a registered SPN then use that ticket to crack the service password. The DC opens the TGT & validates PAC checksum If the DC can open the ticket & the checksum check out, TGT = valid. Your Invoke-Kerberoast from the gist you linked seems to have a bug somewhere. Given GenericWrite/GenericAll DACL rights over a target, we can modify most of the users attributes, save for attributes related to delegation and other protected components like sidHistory. In this post, I'm going to walk through the process of setting up your lab so that you can practice this attack. As Kerberos is an authentication protocol it is possible to perform brute-force attacks against it (providing we are careful). Theres also an excellent page of Microsoft documentation titled , Kerberos Technical Supplement for Windows. Heres myversion of the obligatory this is how kerberos works graphic: As far as how Kerberoasting fits into this process, this is how I understand it (if I am mistaken on some point please let me know! This custom-rolled script includes the, (to enumerate user accounts with a non-null servicePrincipalName) and. Begin offline password cracking with Tims, , or extract a crackable hash format from the raw ticket with John the Rippers. The wordlist was only containing the correct password and four dummies. Blog - harmj0y / /_____ _____/ /_ _______ __/ /____ Your email address will not be published. A Guide to Kerberoasting | RedTeam Talks Kerberos New-Object : Exception calling .ctor with 1 argument(s): The NetworkCredentials provided were unable to create a Targeted Kerberoasting (Harmj0y) Kerberoasting without Mimikatz (Harmj0y) Roasting AS REPs (Harmj0y) Sean Metcalf's Presentations on Active Directory Security; Kerberoast (GitHub) Tim Medin's DerbyCon "Attacking Microsoft Kerberos Kicking the Guard Dog of Hades" presentation in 2014 (slides & video). 5.The user connects to the server hosting the service on the appropriate port & presents the TGS (AP-REQ). I first heard about Kerberoasting from Tim at SANS HackFest 2014 during his Attacking Kerberos: Kicking the Guard Dog of Hades talk (he also released a Kerberoasting toolkit here). Well, you need a ticket-granting-ticket to build the raw TGS-REQ service ticket request, so you need to either a) be elevated on a system and extract out another users TGT or b) have a users hash that you use with the asktgt module to request a new TGT. flag only Kerberoasts accounts with AdminCount=1, meaning user accounts that are (or were) protected and, therefore, almost always highly privileged: Note that for non-Empire weaponizations, as PSObjects are output, you will need to pipe the results to, in order to preserve the information you want displayed. For more details, read this article from HackTricks. This is why inter-domain trust tickets end up using RC4 by default: However, like with user objects, this behavior can be changed by modifying the properties of the trusted domain object, specifying that the foreign domain supports AES: This sets msDS-SupportedEncryptionTypes on the trusted domain object to a value of 24 (AES128_CTS_HMAC_SHA1_96 | AES256_CTS_HMAC_SHA1_96), meaning that AES256 inter-domain trust tickets will be issued by default: Due to the way we tend to execute engagements, we often lean towards abusing host-based functionality versus piping in our own protocol implementation from an attacker server. I handed the hash over to my windows based hashcat machine using hashcat64.exe -m 13300 hashfile D:\wordlists\testlist. This custom-rolled script includes the Invoke-Kerberoast function, which wraps the logic from Get-NetUser -SPN (to enumerate user accounts with a non-null servicePrincipalName) and Get-SPNTicket to request associated TGS tickets and output John and Hashcat crackable strings. Required fields are marked *. CONTROLLER-1/SQLService.CONTROLLER.local:30111 SQLService CN=Group Policy Creator Owners,OU=Groups,DC=CONTROLLER,DC=local 2020-05-26 00:28:26.922527 2020-05-26 00:46:42.467441 The three main encryption key types were going to be referring to in this post are RC4_HMAC_MD5 (ARCFOUR-HMAC-MD5, where an accounts NTLM hash functions as the key), AES128_CTS_HMAC_SHA1_96, and AES256_CTS_HMAC_SHA1_96.

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