kerberos golden ticket attack

Once attackers have injected the Golden Ticket, they have unfettered network access to the entire domain controller. Although TGT timestamps are not recorded in the Kerberos authentication logs, proper Active Directory security solutions are capable of monitoring them. The Splunk Threat Research Team focuses on understanding how threats, actors, and vulnerabilities work, and the team replicates attacks which are stored as datasets in theAttack Data repository. Steal or Forge Kerberos Tickets, Technique T1558 - MITRE ATT&CK Our customers stop cybercriminals in their tracks while streamlining workflows. Please turn off your ad blocker and refresh the page to subscribe. Sean Metcalf. See you soon! 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. This technique is called AS-REP roasting and it effectively allows an attacker to perform an offline brute force attack against a users password. Identity Protection such as Falcon Identity Threat Protection to secure an organizations AD and reduce AD security risks. . Hashed passwords act as the encryption keys. Investigate: An attacker must already have access to the system. ATA learns normal replication and ticket usage patterns to automatically detect and alert if an attacker steals the master key. 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. 2005-2023 Splunk Inc. All rights reserved. How Microsoft Advanced Threat Analytics detects golden ticket attacks For more information, visit this analytic story. As part of continuous security assessments, enterprise security professionals should perform thorough assessments of Active Directory and invest in comprehensive reports on AD attacks. This effectively allows attackers to impersonate any user, including high privileged users, and perform unauthorized actions on them. To learn more about how to protect your enterprise from identity-based threats, sign up for a free Active Directory assessment here. 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. Details about the counterfeit ticket (e.g., the account that the adversary is masquerading as), What resources were used to access the counterfeit ticket. The KRBTGT accounts password is used to encrypt and decrypt Kerberos tickets. (n.d.). The system believes the attacker is the Administrator because of the RID of 500 they used to generate the Golden Ticket. Defend data in Salesforce, Google, AWS, and beyond. 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). This detection will only trigger on domain controllers, not on member servers or workstations. Get-ADUser is part of the Active Directory PowerShell module used to manage Windows Active Directory networks. Abolins, D., Boldea, C., Socha, K., Soria-Machado, M. (2016, April 26). With the appropriate parameters, Set-ADAccountControl allows adversaries to disable Kerberos Pre-Authentication for an account. Like this article? Threat actors then use these hashes to create their Golden Ticket and potentially run a Pass the Ticket (PtT) attack, moving laterally within an organizations AD environment, as per the following code. This validation can be stealthy as it does not actually generate failed authentication or lockout events. Reveal(x) automatically detects Kerberos requests for TGS tickets (TGS_REQ) sent over the network that include indicators of a forged TGT. When a domain-joined endpoint connects to a remote endpoint, it first will request a Kerberos Ticket with the computer name as the Service Name. Only the KRBTGT in the domain can open and read TGT data. A ticket in cybersecurity terms is a number created by a network server as proof of authentication or authorization. The steps below detail how an attacker gets this information, and how they are then able to carry out the attack. by accessing user data stored in Microsoft Active Directory (AD). Our goal is to provide security teams with research they can leverage in their day to day operations and to become the industry standard for SIEM detections. 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. Various attack methods utilize weak Kerberos encryption cyphers. Attackers will then investigate and gather intel like the domain name. Now it is time to use the Golden Ticket that was loaded into the current session. With the hash of this compromised account and some information about the domain, an attacker can create fraudulent tickets. Limit domain admin account permissions to domain controllers and limited servers. Kerberos Attack: How to Stop Golden Tickets? Changing the password twice ensures that any ticket signed with a stolen KDC key will be invalidated. To forge a TGT, hackers need four key pieces of information: The first three are relatively easy to obtain simply by compromising any user account in the domain. Jeff Warren is SVP of Products at Netwrix. You can audit Kerberos AS and TGS events for discrepancies. 2015-2023, The MITRE Corporation. Without Kerberos, users would need to constantly submit plaintext passwords to interact with network services. The following best practices can help prevent attackers from gaining access. 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. The Windows advanced audit policy configuration provides defenders with two Kerberos logging categories: Audit Kerberos Authentication Service and Audit Kerberos Service Ticket Operations. [Free Guide]Active Directory Security Best Practices, Lateral Movement to the Cloud with Pass-the-PRT, Top Strategies to Harden Your Active Directory Infrastructure, Attacking Constrained Delegation to Elevate Access, The name and SID of the domain to which the KRBTGT account belongs. The attack allows an adversary to gain unconstrained access to all services and resources within an Active Directory (AD) domain using a forged Kerberos ticket known as the "Golden Ticket". We will see in a moment how when these values come into play when this ticket is used. Stand up to threats with real-time detection and fast response. For other detection ideas for lateral movement, make sure to visit our Active Directory Lateral Movement analytic story. If the KDC prompts for authentication, the user is valid. They might use techniques such as Pass-the-Hash (PtH) because unlike other credential theft attacks, this attack does not require the attacker to crack the password. Golden Ticket attacks are intertwined with the open source tool Mimikatz, which is an open-source tool created in 2011 as a way to demonstrate the flaws in Microsoft Windows. [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. 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. Kerberos is the default authentication protocol used on Windows Active Directory networks since the introduction of Windows Server 2003. Lets see how this powerful attack unfolds and what you can do to defend your organization. The authentication server, or AS, performs the initial authentication of the user. It exploits weaknesses in the Kerberos identity authentication protocol, which is used to access the AD, allowing an attacker to bypass normal authentication. 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. (2014, November 10). Learn how they work and how to prevent them. Both categories are disabled by default and provide six types of events generated only on domain controllers when specific actions occur. Microsoft advises that rebooting a computer is the only reliable way to recover functionality, since this will force both the computer account and the user account to log back in again, which in turn ensures that they get new TGTs encrypted with the new KRBTGT password hash. maps to the MITRE ATT&CK Credential Access technique under the sub-technique Steal or Forge Kerberos Tickets. Here's the general workflow for a golden ticket attack. By obtaining the password hash for this account from the Key Distribution Center (KDC), an attacker is able to compromise every account in Active Directory, giving them unlimited and virtually undetectable access to any system connected to the AD network. Kerberos Attack: How to Stop Golden Tickets? Golden Ticket attacks have a playful name but they are a serious threat to every Active Directory environment. Following the Splunk Threat Research Teams methodology to create and test the detections released in every analytic story, we simulated all the Kerberos-based attacks in a lab environment built with the Attack Range and stored the resulting telemetry in the Attack Data project. Persistence and privilege escalation security alerts - Microsoft This detection will only trigger on domain controllers, not on member servers or workstations. Golden Ticket Theory; Golden Ticket from Windows ; Golden Ticket from Linux ; OPSEC ; Golden Ticket Theory Golden Ticket from Windows Golden Ticket from Linux OPSEC . Harmj0y. Defenders can leverage these datasets to build or test their detections. Enter your search term. It is virtually impossible to turn a hashed password back into the original password directly; however, hackers can use a brute-force method generating the hashes of millions of possible passwords in the hope of finding one that matches.). Kerberos Golden Ticket Protection. Identifying an unknown process using this protocol may be evidence of an adversary abusing the Kerberos protocol. Windows PowerView Unconstrained Delegation Discovery, This analytic utilizes PowerShell Script Block Logging (EventCode=4104). 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. 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. Get expert advice on enhancing security, data governance and IT operations. Alternatively, threat actors use Mimikatz to retrieve the hash of the KRBTGT account from the Local Security Authority (LSA) by executing Mimikatz commands privilege::debug and lsadump::lsa /inject /name:krbtgt on the DC. Varonis debuts trailblazing features for securing Salesforce. T1558.002. Step 4. Kerberos in the Crosshairs: Golden Tickets, Silver Tickets, MITM, and More November 24, 2014 It's been a rough year for Microsoft's Kerberos implementation. What can you do about it? A golden ticket attack is one in which you create a Kerberos-generating ticket that is good for 10 years or however long you choose. Join 7,000+ organizations that traded data darkness for automated protection. Download: CrowdStrike CrowdStrike Falcon XDR Data Sheet. Splunk Security Essentials also has all these detections available via push update. While convenient, this Kerberos feature introduces new attack vectors that allow adversaries to abuse accounts or computers trusted for the delegation intending to steal Kerberos Ticket Granting Tickets or obtain unauthorized Kerberos Service Tickets. Identifies one source endpoint failing to authenticate with multiple invalid domain users using the Kerberos protocol. Other indicators of a golden ticket attack can include TGS ticket requests without previous TGT requests or TGT tickets with arbitrary lifetime values. Its a Golden Ticket (just like in Willy Wonka) to ALL of your computers, files, folders, and most importantly Domain Controllers (DC). The ticket is then evaluated by the service. Make sure its prominent, give it a tempting username and give it membership in some interesting groups. Get hands-on with ExtraHop's cloud-native NDR platform in a capture the flag style event. Steal or Forge Kerberos Tickets: Golden Ticket, Sub-technique T1558.001 This analytic leverages Kerberos Event 4769 to identify a potential Kerberos Service Ticket request related to a Golden Ticket attack. Adversaries who have the KRBTGT account password hash may forge Kerberos ticket-granting tickets (TGT), also known as a golden ticket. Kerberoasting spn request with RC4 encryption. [1] Golden tickets enable adversaries to generate authentication material for any account in Active Directory. Categories: Red Teaming. Golden Ticket attacks are post-exploitation attacks, meaning that the environment needs to be compromised before an attacker carries out the attack. That way, an attacker who manages to get a foothold on an endpoint wont find any privileged credentials there to harvest and use in a Golden Ticket attack. However, all authenticated sessions that have been established to a resource (such as a file share, SharePoint site or Exchange server) are good until the service ticket is required to re-authenticate. RC4-HMAC. Retain Access: The ticket can be made valid for up to 10 years, and this type of attack is often not detected. The TGTs also grants the attacker unrestricted access to resources to assign others any domain-related tasks and allows them to create tickets. This encryption type is no longer utilized by newer systems and could represent evidence of an OverPass The Hash attack. ExtraHop uses cookies to improve your online experience. This service is typically run in each domain controller within an Active Directory (AD) domain. Kerberos is built on symmetric-key encryption (shared secrets). Once an adversary is able to log on interactively or remotely to a DC, they can use Mimikatz to extract the required information using the following commands: This will output the password hash, as well as the domain name and SID: Now the hacker can create Golden Tickets at will. With the power of machine learning, gain the insight you need to solve pressing challenges. Book a demo and see the worlds most advanced cybersecurity platform in action. To enable authentication, SPNs are typically associated with a domain service account. Rubeus will try to escalate privileges to SYSTEM by obtaining a handle to winlogon.exe before trying to monitor for Kerberos tickets. That Golden Ticket can then use a pass-the-hash technique to log into any account, allowing attackers to move around unnoticed inside the network. Tickets: tokens that serve as a proof of identity. In addition to those scheduled updates, I strongly advise changing the password every time a human who had the ability to create a Golden Ticket leaves the organization. Kerberos TGT Request Using RC4 Encryption, This analytic leverages Event 4768. What is a Golden Ticket Attack? This analytic looks for the use of Mimikatz command line parameters leveraged to execute pass the ticket attacks. As an increasing number of companies shift both to the cloud and a remote-first setting, the attack surface has grown beyond the traditional perimeter, with employees logging into company systems using their own devices and networks. If theyre already in the network, one option to take over a privileged account is with a brute force attack, which Varonis can detect with this threat model: Threat Model: Abnormal admin behavior: accumulative increase in lockouts for individual admin accountsHow it works: DatAlert detects statistically significant increases in lock-out events over time and can identify an unusual amount of lock-out events on an admin account compared to their typical behavior.What it means: It means that the account is trying to login and failing repeatedly. Follow us on LinkedIn, As part of the sAMAccountName Spoofing and Domain Controller Impersonation exploitation chain, adversaries will need to request a Kerberos Ticket Granting Ticket (TGT) on behalf of the newly created and renamed computer account. What is the KRBTGT account in AD? 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. 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. Kerberos Attacks: Golden Ticket - Daniel Pramatarov This intelligence can drive our logging requirements as well as content prioritization. You can rebuild the DC, but that authentication token is still valid. Rubeus. You may withdraw your consent at any time. Finally, it probably goes without saying that you need to immediately change the KRBTGT password if you spot any evidence of a Golden Ticket attack in your IT environment. Multiple Invalid Users Failing To Authenticate From Host Using Kerberos. This analytic leverages Event Id 4781, The name of an account was changed and event Id 4768 A Kerberos authentication ticket (TGT) was requested to correlate a sequence of events where the new computer account on event id 4781 matches the request account on event id 4768. Another tip is to set up an alert that will notify the security team whenever a service principal name (SPN) is created or modified, so they can check that all relevant policies were followed. Retrieved December 23, 2015. Before joining Stealthbits - now part of Netwrix, Jeff was a Software Engineer at Wall Street Network, a solutions provider specializing in GIS software and custom SharePoint development. Moreover, they can make those tickets valid for as long as they want, even if that violates the organizations time limit policy setting. Of course, whenever possible, replace regular service accounts withgroup managed service accounts, which provide automatic password management. Note that this is a work in progress and does not cover all the existing Kerberos attack techniques. * Inventory unmanaged devices and IoT. This gives the attacker access to any resource on an Active Directory Domain (thus: a "Golden Ticket"). 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. Identity-based security needs to be an integral part of an enterprises cybersecurity strategy as threat actors continue to exploit attack methods like the Golden Ticket attack. Consider rotating the KRBTGT account password every 180 days.[10]. 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. Through secured digital identities, enterprises standardize access management and authentication processes to ensure the right users see the right information. The KDC trusts the golden ticket and creates a TGS ticket with the fake PAC. The TGT is proof that the client submitted valid user information to the KDC. Its always the same string, so two computers can each hash a password and compare the results; if they match, they agree they both started from the same password without ever having to directly share that password in plain text. 444 Castro Street 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. A Golden Ticket attack is a malicious cybersecurity attack in which a threat actor attempts to gain almost unlimited access to an organizations domain (devices, files, domain controllers, etc.) 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. Splunk, Splunk> and Turn Data Into Doing are trademarks or registered trademarks of Splunk Inc. in the United States and other countries. This could be a misconfigured password for a valid user, or it could be an attempt to brute force or guess the password by an outsider. Monitor and protect your file shares and hybrid NAS. Monitor for anomalous Kerberos activity, such as malformed or blank fields in Windows logon/logoff events (Event ID 4624, 4634, 4672). T1558.004. Please visit our Privacy Statement for additional information, Golden ticket attacks: How they work and how to defend against them. To keep up with ongoing technological changes, the digital identity landscape and methods of securing also need to be adaptable. As the name suggests, Get-ADUser is used to query for domain users. Examples included. July 22, 2022 A Golden Ticket attack is a malicious cybersecurity attack in which a threat actor attempts to gain almost unlimited access to an organization's domain (devices, files, domain controllers, etc.) Let's review the basic components in a Microsoft Kerberos Active Directory authentication workflow that are relevant to a golden ticket attack. Human-led threat hunting enables 24/7 hunting for unknown and stealthy attacks that utilize stolen credentials and are conducted under the guise of legitimate users. Share information, boost collaboration without sacrificing security. That doesnt prevent hackers from creating Golden Tickets, but it invalidates any that are already in your systems. Dont give end users admin authority on their workstations, and dont let admins log on to end-user computers. A golden ticket enables the attacker to create a fake domain administrator identity to gain access to any service on a domain. With Kerberos, users never directly authenticate themselves to the various services they need to use, such as file servers. 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. The Golden Ticket attack was named such because it exploits a vulnerability in the Kerberos authentication protocol. Follow these instructions If you need an invitation to our Splunk user groups on Slack. The analytic story presented in this blog post groups detection use cases in which the Kerberos protocol is abused. In terms of a long-term mitigation strategy: In todays fast-paced working environment, users are expected to use their digital identities to transact quickly and securely. Kerberos: Golden Tickets - Red Team Notes Learn why it's (honestly) a weird approach to take. Kerberos Pre-Authentication Flag Disabled. 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. The most insidious part about this attack is you can change the password for the KRBTGT account, but the authentication token is still valid. This behavior has been identified to assist with detecting PetitPotam, CVE-2021-36942. Learn More, Varonis named a Leader in The Forrester Wave: Data Security Platforms, Q1 2023. Alert on known behavior that indicates Golden Ticket attacks, Infect the target computer with malware that allows attackers to leverage user accounts to access other network resources (often via a phishing email or some other vulnerability), Get access to an account with elevated privileges with access to the Domain Controllers (DC), Log into the DC and dump the password hash for the KRBTGT account to create the Golden Ticket. Important technical note: Kerberos uses authentication tokens, or tickets, to verify identities of Active Directory entities. Github PowerShellEmpire. Metcalf, S. (2015, August 7). Investigate a live attack in the full product demo of ExtraHop Reveal(x), network detection and response, to see how it accelerates workflows. Kerberos Attack: Silver Ticket Edition - Varonis Strategic Cyber LLC. If you've already registered, sign in. This analytic identifies the execution of the Get-ADUser commandlet with specific parameters. TGTs are used when requesting Ticket Granting Service (TGS) tickets, which means a forged TGT can get us any TGS ticket - hence it's golden. Golden tickets require adversaries to interact with the Key Distribution Center (KDC) in order to obtain TGS.[3]. You can close the security breach and disable the attackers access into your network. This can be accomplished by submitting a TGT request with no pre-authentication. The culmination was last week when Microsoft announced critical vulnerability MS14-068. 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. Taking advantage, threat actors are acutely aware of how reliant organizations are on this means of identification. Modern technology has transformed the workplace, changing how people access data and operate in tandem with various software. 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. This can be particularly useful for attackers looking to evade detection or create deceptive security logs. 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.
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