Get a free risk assessment to see where you may be vulnerable to security breaches, including a Golden Ticket attack and sign up for a 1:1 demo to see how to detect abnormal behavior that indicates an attack in-progress, and defend against a golden ticket attack. Password spraying, credential stuffing, brute force attacksthe similarities extend beyond their names. Defenders can leverage these datasets to build or test their detections. Check out the, Compromise Software Dependencies and Development Tools, Windows Management Instrumentation Event Subscription, Executable Installer File Permissions Weakness, Path Interception by PATH Environment Variable, Path Interception by Search Order Hijacking, File and Directory Permissions Modification, Windows File and Directory Permissions Modification, Linux and Mac File and Directory Permissions Modification, Clear Network Connection History and Configurations, Trusted Developer Utilities Proxy Execution, Multi-Factor Authentication Request Generation, Steal or Forge Authentication Certificates, Exfiltration Over Symmetric Encrypted Non-C2 Protocol, Exfiltration Over Asymmetric Encrypted Non-C2 Protocol, Exfiltration Over Unencrypted Non-C2 Protocol. Also limit the number of servers a domain administrator logs into, and delegate administrative privileges to custom administrator groups. Zero Trust enforcement never trust, always verify aids in protecting AD and identities, and ensures that users have been continuously verified and authorized before gaining access to any data. [9], For containing the impact of a previously generated golden ticket, reset the built-in KRBTGT account password twice, which will invalidate any existing golden tickets that have been created with the KRBTGT hash and other Kerberos tickets derived from it. [4] The KRBTGT password hash may be obtained using OS Credential Dumping and privileged access to a domain controller. In this case, the DFIR team investigated the alert and identified this incident to be the result of an advanced attacker leveraging a golden ticket in their environment. by accessing user data stored in Microsoft Active Directory (AD). In June 2021, Will Schroeder and Lee Christensen released the whitepaper Certified Pre-Owned: Abusing Active Directory Certificate Services which described scenarios to abuse Microsofts PKI implementation called Active Directory Certificate Services. Learn how this type of attack works, associated indicators of compromise, and how best to mitigate and protect against it. The Splunk Threat Research team identified this behavior when using the Rubeus tool to monitor for and export Kerberos tickets from memory. The KDC automatically trusts a TGT that is encrypted with a KDC key. XDR solutions can integrate all detection and responses into one command console, enabling an organization to detect a Golden Ticket attack faster with the integrated threat data from across the technology stack. Monitor and protect your file shares and hybrid NAS. The ticket is then evaluated by the service. That password hash is shared among all the DCs in the Active Directory domain so that they can read the TGTs they receive as users request access to various resources. There are several processes organizations should have in place to be able to detect a possible Golden Ticket attack. Kerberoasting allows an adversary to request Kerberos tickets for domain accounts typically used as service accounts and attempts to crack them offline allowing them to obtain privileged access to the domain. When the user needs access to resources, they dont have to re-authenticate; their client machine simply sends the TGT along to prove that the user has already been recently authenticated. T1558.003. Typically, this is a precursor activity related to Kerberoasting or the silver ticket attack. Disabled Kerberos Pre-Authentication Discovery With PowerView. When Kerberos is sent a TGT request without prior authentication, it will return different messages depending on if the login credentials are valid or not. Get-ADUser is part of the Active Directory PowerShell module used to manage Windows Active Directory networks. Password spraying is a technique by which adversaries leverage a single password or a small list of commonly used passwords against a large group of usernames to acquire valid account credentials. Learn how a Kerberos golden ticket attack works, how ExtraHop Reveal(x) detects golden ticket attacks, and how to protect your environment against these attacks. In Active Directory, accounts sign in with a username and password, maybe some other form of authentication, and they then get back a Kerberos ticket that contains their authentication token. SentinelOnes annual user conference. (2020, November 5). Important:Be aware that changing the KRBTGT password will affect almost all subsequent Kerberos operations. Kerberos, initially named after Cerberus, the three-headed dog in Greek mythology, is a network authentication protocol that allows computers and users to prove their identity through a trusted third party. In short, Kerberos authentication the default authentication protocol in Active Directory is built upon the assumption that any TGT encrypted with the KRBTGT password hash is legitimate. This hunting analytic leverages Event ID 4769. Automated tools combined with previously discovered customer and employee information are used to find active accounts. Of course, whenever possible, replace regular service accounts withgroup managed service accounts, which provide automatic password management. OverPass The Hash is a technique by which an attacker, who has obtained NTLM hash passwords, is able to authenticate to the Key Distribution Center using this hash and receive a valid Kerberos ticket (TGT) on behalf of the compromised user. Step 4. Watch the video below where we simulate a few Kerberos attacks using open source tools like Rubeus, Kerbrute, and PurpleSharp. Complete Domain Compromise with a Golden Ticket Attack. Adversaries who have obtained system privileges on a Windows host are able to export the valid Kerberos Ticket Granting Tickets as well as Kerberos Service Tickets that reside in memory. With Mimikatz, the attacker can bypass the step of compromising the DC to steal the KRBTGT account hash (KDC key) with a technique called DCSync (1). Updated: May 4, 2023. Get-DomainUser is part of PowerView, a PowerShell tool used to perform enumeration on Windows Active Directory networks. Specifically, when a user authenticates, the KDC issues aticket granting ticket(TGT), which includes a unique session key and a timestamp that specifies how long that session is valid (normally 8 or 10 hours). [2], Using a golden ticket, adversaries are then able to request ticket granting service (TGS) tickets, which enable access to specific resources. Retrieved March 29, 2023. Leveraging this attack, an adversary who has stolen the NTLM hash of a valid domain account can authenticate to the Kerberos Distribution Center (KDC) on behalf of the legitimate account and obtain a Kerberos TGT ticket. Alternatively, join us on the Slack channel #security-research. Next, the client requests access to a servicerepresented as the service principal name (SPN)by sending the encrypted TGT and the SPN to the KDC. Generally, attackers will set the tickets to be valid for a shorter period of time to further escape detection. [7][8], Rubeus can forge a ticket-granting ticket. Adversaries who have obtained the Krbtgt account NTLM password hash may forge a Kerberos Granting Ticket (TGT) to obtain unrestricted access to an Active Directory environment. Microsoft details thesteps for manually changing the KRBTGT password, but its usually better to use theKRBTGT password reset script from Microsoft it will change the password once, wait to make sure replication has gone all the way through to all your domain controllers, and then change the password again. To keep up with ongoing technological changes, the digital identity landscape and methods of securing also need to be adaptable. Learn more. Its incredibly difficult to clean up after a Golden Ticket is created for your domain. This analytic identifies the execution of the Set-ADAccountControl commandlet with specific parameters. What is a Silver Ticket Attack? Golden Ticket attacks have a playful name but they are a serious threat to every Active Directory environment. This analytic identifies a process performing an outbound connection on port 88 used by default by the network authentication protocol Kerberos. Golden Ticket attacks are post-exploitation attacks, meaning that the environment needs to be compromised before an attacker carries out the attack. Github PowerShellEmpire. They can impersonate anyone and do just about anything. AS-REP Roasting. Golden Ticket attack is a particularly colorful (if youll pardon the pun) name for a particularly dangerous attack. As the backbone of Active Directory authentication, Kerberos is commonly abused by adversaries across the different phases of a breach including initial access, privilege escalation, defense evasion, credential access, lateral movement, etc. That gives them nearly unlimited power in the domain. Golden ticket can also be created offline. Identity Protection such as Falcon Identity Threat Protection to secure an organizations AD and reduce AD security risks. Empire can leverage its implementation of Mimikatz to obtain and use golden tickets. If you do see that Golden Tickets are in use within your organization, you must reset the KRBTGT account twice; doing so can have far-reaching consequences, so proceed with caution. Finally, the client sends the TGS ticket to the service. The good news: protecting yourself from a Golden Ticket attack is not all that different from protecting yourself any other malware or infiltration attack. To carry out a Golden Ticket attack, the attacker needs the fully qualified domain name, the security identifier of the domain, the KRBTGT password hash and the username of the account they are going to access. ServicePrincipalNames Discovery with SetSPN. Defeat every attack, at every stage of the threat lifecycle with SentinelOne. With this kind of immediate notice you will be able to take steps to reset all the passwords, the KRBTGT you need to change twice, invalidate any current Kerberos authentication tokens, and create new tokens for your users. Multiple Invalid Users Failing To Authenticate From Host Using Kerberos. This behavior has been identified to assist with detecting PetitPotam, CVE-2021-36942. How does a Golden Ticket Attack work? Depending on the privileges of the compromised account, this ticket may be used to obtain unauthorized access to systems and other network resources. However, because the Kerberos ticket is in memory, its possible to connect to a domain controller and gain access to all of the files stored there. Correlate other security systems with login information (e.g., a user has the KRBTGT account password hash and forges Kerberos ticket-granting tickets). The Kerberos communication process follows the below steps: The system converts a user's password to a NTLM hash, encrypts a timestamp with the hash and sends it to the Key Distribution Center (KDC) as an authenticator in the authentication ticket (TGT) request. Note that this is a work in progress and does not cover all the existing Kerberos attack techniques. Kerberos Golden Tickets are Now More Golden. Useful Mimikatz parameters for creating Golden Tickets include: The following example creates a ticket for a fake user but provides the default administrator ID. In this blog post, we'll briefly explain what Kerberos and a Golden Ticket are and an attacker's motivation for performing a Golden Ticket attack. visit our Password Spraying analytic story, Certified Pre-Owned: Abusing Active Directory Certificate Services. Monitoring AD constantly for any unusual behavior and putting systems in place to ensure that unauthorized users do not get access is imperative in preventing Golden Ticket attacks, versus having to respond to the attack when damage has already been done. To do that, hackers have a wide variety of tactics at their disposal; popular ones include phishing, spyware, brute force and credential stuffing. To do this, an attacker must establish themselves on the network, escalate their privileges, and compromise the DC. Active Directory Golden Ticket attacks are very difficult to detect because Golden Tickets look like perfectly valid TGTs. Kerberos Attack: How to Stop Golden Tickets? KDC key: an encryption key that proves the TGT is valid. Details about the counterfeit ticket (e.g., the account that the adversary is masquerading as), What resources were used to access the counterfeit ticket. Credit to author Mauricio Velazco and collaborators Michael Haag, Patrick Bareis, Jose Hernandez, Teoderick Contreras, Eric McGinnis, Rod Soto, and Lou Stella. Now it is time to use the Golden Ticket that was loaded into the current session. 2015-2023, The MITRE Corporation. Despite the entertaining reference to Charlie and the Chocolate Factory, a golden ticket attack is extremely dangerous. The KDC trusts the golden ticket and creates a TGS ticket with the fake PAC. A ticket in cybersecurity terms is a number created by a network server as proof of authentication or authorization. Microsoft recommendsregular password updatesto the KRBTGT account, whileSTIG specifically recommends changing it every 180 days. Suspicious Kerberos Service Ticket Request. When threat actors carry out Golden Ticket attacks, they begin by logging onto a domain-joined computer with compromised user credentials and target the Kerberos communication process. This type of attack can fly under the radar and escape detection by automated security tools. Before being able to export tickets. This request will generate a 4768 event with some unusual fields depending on the environment. By using this website, you consent to the use of cookies. Step 1. This analytic identifies the execution of the Get-DomainUser commandlet with specific parameters. The KDC key is created from the hashed password of the. The user presents the TGT and requests a Ticket Granting Service (TGS) ticket. Thisblog post series covers techniques that attackers can use to find and compromise Active Directory service accounts. Delegate other admin functions to separate accounts. (You can enhance Kerberos detection capabilities by enabling DC-assisted decryption in Reveal(x). A Kerberos service ticket was requested to identify an unusual number of computer service ticket requests from one source. What can you do about it? In addition, a tiered logon protocol should be used to prevent Domain Admins from logging on to servers and workstations where their password hashes can be dumped from memory and used to access a DC to extract the KRBTGT account hash. Once attackers have injected the Golden Ticket, they have unfettered network access to the entire domain controller. IT hygiene tools help ensure that all credentials are safe and passwords are changed regularly so if a system has been compromised, the attack will be detected and stopped. First, the client sends user informationincluding the client principal name (CPN)to the KDC. Why NDR? You will also find us presenting our research at conferences such as Defcon, Blackhat, RSA, and many more. This Service Ticket can be then used to take control of the domain controller on the final part of the attack. Are you ready to join us? Steal Access: After an attacker has access to the domain controller, they will then steal an NTLM hash of the Active Directory Key Distribution Service Account (KRBTGT). To create KerberosGolden Tickets, an adversary needs the following information: Lets take a look at how to gather this information and create Golden Tickets for Kerberos, step by step. In particular, all the TGTs that have been issued will be invalid since they were encrypted with the old password. Some commands, such as kerberos::list and kerberos::tgt, are also supported in the Mimikatz module to retrieve all the available Kerberos tickets submitted for the current user session. The DC stores two versions of the KRBTGT password (a current and previous version), which enables the KDC to check whether an invalid TGT has a KDC key that matches a previous KRBTGT password. In the scenario that a high-privileged account has an active session on the compromised host, tickets can be dumped and reused to consume services and resources on the network in a similar way to the Pass The Hash NTLM attack. Our partners help extend the upper hand to more teams, across more platforms. With the power of machine learning, gain the insight you need to solve pressing challenges. This blog post breaks down the Golden Ticket attack, an identity-based attack that exploits weaknesses in the Kerberos authentication protocol. Windows Active Directory domain controllers are responsible for handling Kerberos ticket requests, which are used to authenticate users and grant them access to computers and applications. Sharing best practices for building any app with .NET. The Kerberos authentication workflow revolves around tickets, which act as a cryptographic proof of identity that can be exchanged between clients, services, and the DC. * Detect network attacks. Items to monitor or get alerted on include the following: Unfortunately, the native Windows event logs do not include the TGT timestamps and ferreting out suspicious truly activity in the ocean of events can be a real challenge. Read an example of how one government organization safeguarded its data by using ExtraHop Reveal(x) to detect an attempted SQL injection attack. With deep knowledge and experience in technology, product and project management, Jeff and his teams are responsible for designing and delivering Stealthbits high quality, innovative solutions. You can rebuild the DC, but that authentication token is still valid. Restore business operations, data integrity and customer trust in minutes or hours instead of weeks or months, Empower enterprise stakeholders to use data assets strategically for data operations, data protection and data governance, Protect and recover all your systems, applications and data while reducing backup storage costs, Achieve identity-centric cybersecurity to protect the people, applications and data that are essential to business, Conquer your next migration (now and in the future) by making it a non-event for end users, Discover, manage and secure evolving hybrid workforce environments, Mitigate risk with attack path management, threat detection and disaster recovery. Retrieved December 1, 2017. Disabling the Pre Authentication flag in the UserAccountControl property allows an adversary to easily perform a brute force attack against the users password offline leveraging the ASP REP Roasting technique. A security team has plenty of time to remove the RAT from the users computer and change the users password long before the attacker has time to get a foothold in your organization. This attack is known as Kerberoasting and allows adversaries to perform an offline brute force attack to attempt to obtain the service account's password. Kerberos delegation is an impersonation capability that enables an application to access or consume resources hosted on a different server on behalf of users.
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