Obtaining the KRBTGT password hash is the hardest part of the attack because it requires gaining privileged access to a domain controller. (2020, November 5). Every domain controller in an Active Directory domain runs a KDC service. A Silver Ticket is just as nasty and invasive, and even stealthier. (You can enhance Kerberos detection capabilities by enabling DC-assisted decryption in Reveal(x). Learn from ExtraHop how ICMP tunneling attacks work and what you can do to protect against them. If an attacker is already in the system and has successfully created a Golden Ticket, youll be able to spot them when they use that Golden Ticket to log into an account with their full domain access privileges: Threat Model: Potential pass-the-ticket attackHow it works: Varonis detected that a user account accessed a resource without authentication, meaning they bypassed the Kerberos protocol, possibly a successful Golden Ticket attack.What it means: An attacker succeeded in a pass-the-hash attack, they might have a Golden Ticket, and they are logging in with those credentials right now.Where it works: Directory Services. The PAC is built into both TGT and TGS tickets. Why NDR? A Golden Ticket is a forged Kerberos Ticket-Granting Tickets (TGT) that enables attackers to generate Ticket Granting Service (TGS) tickets for any account in Active Directory and gain unrestricted access to the target resources. Kerberoasting. Below are three ways we can help you begin your journey to reducing data risk at your company: Michael has worked as a sysadmin and software developer for Silicon Valley startups, the US Navy, and everything in between. Get expert advice on enhancing security, data governance and IT operations. A TGS ticket is created for each service that the client (with a valid TGT) wants to access. * Detect network attacks. Seattle Children's and ExtraHop Reveal(x)Protecting More Than Data. ), Routinely update the KRBTGT password twice. Find white papers, reports, datasheets, and more by exploring our full resource archive. Theres some instances where an attacker may have had a Golden Ticket for several years: theres no telling what the attackers were able to steal. Identifies one source endpoint failing to authenticate with multiple invalid domain users using the Kerberos protocol. Learn More, Ransomware Attacks in 2021: A Retrospective. Kerberos is built on symmetric-key encryption (shared secrets). Step 3. Threat Model: Abnormal behavior: activity from new geolocation to the organizationHow it works: Any activity that originates outside of known geolocations will trigger this threat model.What it means: Someone attempted to reach into the network through the VPN from a new geolocation.Where it works: VPN. Without Kerberos, users would need to constantly submit plaintext passwords to interact with network services. Monitor for anomalous Kerberos activity, such as malformed or blank fields in Windows logon/logoff events (Event ID 4769, 4768), RC4 encryption within TGTs, and TGS requests without preceding TGT requests. Employing the expertise gained from daily hand-to-hand combat with sophisticated advanced persistent threat (APT) actors, threat hunting teams can finds and track millions of subtle hunting leads daily to validate if they are legitimate or malicious, alerting customers when necessary. 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. Identifies one source endpoint failing to authenticate with multiple valid users using the Kerberos protocol. Launch Attack: Once an attacker has the password for the KRBTGT, they can get a TGT, which then allows access to the domain controller, and verifies the identity of the server. They include: However its obtained, the KRBTGT password hash is like Willy Wonkas golden ticket. Sharing best practices for building any app with .NET. Changing the password twice ensures that any ticket signed with a stolen KDC key will be invalidated. 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. 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. It is important to understand the communication process before analyzing the methodology of the attack. This detection will only trigger on domain controllers, not on member servers or workstations. However, the analogy breaks down in one important way: While Charlie and the other children with golden tickets were (mostly) escorted around the candy factory under close supervision, a successful Golden Ticket attack gives the hacker nearly unfettered access to everything in your domain, including all computers, files, folders and domain controllers (DCs). 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. Our threat models are engineered from the ground up to detect activity and potential attacks throughout the kill chain. Importantly, before sending a TGT, the KDC encrypts it using the password hash for a special account, theKRBTGT account. This security concept ensures that users are only given the access rights that are necessary to the users job tasks. Note that the password history value for the KRBTGT account is 2, which means it includes the two most recent passwords. Details about the counterfeit ticket (e.g., the account that the adversary is masquerading as), What resources were used to access the counterfeit ticket. to identify commandlets used by the PowerView hacking tool leveraged to discover Windows endpoints with Kerberos Unconstrained Delegation. Retrieved December 23, 2015. The Splunk Threat Research Team is an active part of a customers overall defense strategy by enhancing Splunk security offerings with verified research and security content such as use cases, detection searches, and playbooks. maps to the MITRE ATT&CK Credential Access technique under the sub-technique Steal or Forge Kerberos Tickets. 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. 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. Tickets: tokens that serve as a proof of identity. Once adversaries gain a foothold within an enterprise, they will seek to expand their access by leveraging techniques that facilitate lateral movement and remote code execution. V for Ventura | How Will Upgrading to macOS 13 Impact Organizations? In this final post, we explore the most powerful service account in any Active Directory environment: the KRBTGT account, which is used to issue the Kerberos tickets required to access IT systems and data. 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. On November 9, 2021, Microsoft released patches to address two vulnerabilities that affect Windows Active Directory domain controllers: sAMAccountName Spoofing (CVE-202142278) and Domain Controller Impersonation (CVE-202142287). Otherwise, register and sign in. Retrieved January 30, 2020. SentinelOnes annual user conference. Feedback is welcome! 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. As the name suggests, Set-ADAccountControl is used to modify User Account Control values for an Active Directory domain account. Learn how and why they target this critical feature of your Active Directory environment. Monitor for indications of Pass the Ticket being used to move laterally. The KRBTGT account's password is used to encrypt and decrypt Kerberos tickets. Suite 400 Be sure you know exactly which accounts could execute the DCSync command. The KDC key is created from the hashed password of the. TGTs are first issued to users as an authentication mechanism after submitting their passwords. The KDC trusts the golden ticket and creates a TGS ticket with the fake PAC. The culmination was last week when Microsoft announced critical vulnerability MS14-068. As part of continuous security assessments, enterprise security professionals should perform thorough assessments of Active Directory and invest in comprehensive reports on AD attacks. MITRE Engenuity ATT&CK Evaluation Results. But stealing the KDC key is not an easy feat. A Golden Ticket attack is meant to go undetected by a security system, and human-led threat hunting is crucial to identify them. 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. Here are the top ones I recommend. [4] The KRBTGT password hash may be obtained using OS Credential Dumping and privileged access to a domain controller. 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. [1] Golden tickets enable adversaries to generate authentication material for any account in Active Directory. Jeff holds a Bachelor of Science degree in Information Systems from the University of Delaware. It's a Golden Ticket (just like in Willy Wonka). See what sets ExtraHop apart, from our innovative approach to our corporate culture. 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. (Hashing is a one-way algorithm that mathematicallytransforms a given password into a different string. If an attacker manages to hack an ADDS administrator account, Mimikatz can create a special Kerberos TGT that has the following basic properties: Golden ticket is a method to generate a TGT of an arbitrary user in ADDS, then the attacker can impersonate anyone in the domain. Adversaries may attempt to subvert Kerberos authentication by stealing or forging Kerberos tickets to enable Pass the Ticket. Splunk Security Essentials also has all these detections available via push update. Follow these recommendations to reduce the attack surface for compromising a domain administrator account and accessing a DC. Irrespective of the used technique (WMI, WinRM, SMB, etc), a lateral movement attack using the Kerberos protocol generates interesting events. Kerberos delegation is an impersonation capability that enables an application to access or consume resources hosted on a different server on behalf of users. If you find any other accounts with access to this critical data, investigate immediately and remove any unnecessary permissions. Alternatively, join us on the Slack channel #security-research. Book a demo and see the worlds most advanced cybersecurity platform in action. We will see in a moment how when these values come into play when this ticket is used. 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. Jeff Warren is SVP of Products at Netwrix. We are using ATT&CK Tactics to organize them. Join 7,000+ organizations that traded data darkness for automated protection. 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). A ticket in cybersecurity terms is a number created by a network server as proof of authentication or authorization. Digital identities allow users to identify themselves electronically and confirm who they are within the scope of an enterprise, software, or service. Resetting the KRBTGT account password twice in a year helps minimize the chances of compromising the entire domain. Just like in the book and movie Charlie and the Chocolate Factory, where the name comes from, the attack is a Golden Ticket that allows unlimited access, but instead of a well-guarded candy factory, its to bypass a companys cybersecurity and gain access to its resources, files, computers and domain controllers. Security admins can also restrict domain administrators from logging on to any computer other than the domain controllers. We then collect and analyze the resulting telemetry to test our detections using Splunk in a lab environment built with the Attack Range. AS-REP Roasting. Learn how to implement a Zero Trust model in on-premises or hybrid Active Directory environments to dramatically strengthen Active Directory security. [6], Mimikatz's kerberos module can create golden tickets. By using this website, you consent to the use of cookies. Here's a general Kerberos workflow that highlights the basic components relevant to a golden ticket attack. Even if you promptly delete their privileged account, they might have left behind TGTs that they could still use to cause havoc in your environment; resetting the KRBTGT password will render all such tickets invalid. Let's review the basic components in a Microsoft Kerberos Active Directory authentication workflow that are relevant to a golden ticket attack. This analytic identifies the execution of the Get-DomainUser commandlet with specific parameters. Categories: Red Teaming. Implement Microsoft Advanced Threat Analytics (ATA), a detection solution that reveals when an adversary has compromised credentials, is using a golden ticket, and/or is moving laterally on your network, escalating privileges, and exerting domain dominance. Learn how they work and how to prevent them. This password rarely changes and the account name is the same in every domain, so it is a common target for attackers. These vulnerabilities allow an adversary with access to low-privileged domain user credentials to obtain a Kerberos Service Ticket for a Domain Controller computer account. Identifies one source endpoint failing to authenticate with multiple disabled domain users using the Kerberos protocol. Updated: May 4, 2023. More importantly, Microsoft ATA will alert you when an adversary begins using a golden ticket on your network. [2] With the power of machine learning, gain the insight you need to solve pressing challenges. 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. The Golden Ticket attack technique maps to the MITRE ATT&CK Credential Access technique under the sub-technique Steal or Forge Kerberos Tickets. Generally, attackers will set the tickets to be valid for a shorter period of time to further escape detection. Multiple Users Failing To Authenticate From Host Using Kerberos. A golden ticket attack allows an attacker to create a Kerberos authentication ticket from a compromised service account, called krbtgt, with the help of Mimikatz. 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. How much sensitive data do you have on the network that is locked down? Is it locked down to a user with Domain Admin credentials? Extended detection and response (XDR) solutions collect threat data from tools across an organizations technology stack, which helps expedite the threat hunting and response process. 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. Suspicious Kerberos Service Ticket Request. 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. Defenders can leverage these analytics to detect and hunt for behavior commonly presented when attackers engage in Kerberos-based attacks. In a Golden Ticket attack, hackers bypass the KDC and create TGTs themselves to get access to various resources. The TGT is proof that the client submitted valid user information to the KDC. Follow us on LinkedIn, The service opens the TGS ticket using its NTLM password hash. This detection will only trigger on domain controllers, not on member servers or workstations. The KDC service runs all on domain controllers that are part of an Active Directory domain. You must be a registered user to add a comment. RC4 usage should be rare on a modern network since Windows Vista & Windows Server 2008 and newer support AES Kerberos encryption. Golden Ticket attack is a particularly colorful (if youll pardon the pun) name for a particularly dangerous attack. command. That gives them nearly unlimited power in the domain. Get-ADUser is part of the Active Directory PowerShell module used to manage Windows Active Directory networks. You can be anyone (assuming you have their hash), add any account to any group (including highly privileged groups), and for that matter, do anything you want within Kerberos authentication capabilities. Zero detection delays. Empire can leverage its implementation of Mimikatz to obtain and use golden tickets. This analytic identifies the execution of the Get-ADUser commandlet with specific parameters. Other indicators of a golden ticket attack can include TGS ticket requests without previous TGT requests or TGT tickets with arbitrary lifetime values. This analytic looks for a specific combination of the Ticket_Options field based on common Kerberoasting tools. Detect data leaks from employee use of ChatGPT in Reveal(x). In an Active Directory environment, both the NTLM and Kerberos protocols can be used for this technique. Share information, boost collaboration without sacrificing security. 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.) Like this article? This analytic identifies powershell.exe usage, using Script Block Logging EventCode 4104, related to querying the domain for Service Principal Names. Lets see how this powerful attack unfolds and what you can do to defend your organization. . Deply, B., Le Toux, V.. (2016, June 5). 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. A large part of these changes involves the exponential increase in digital identities. Splunk, Splunk> and Turn Data Into Doing are trademarks or registered trademarks of Splunk Inc. in the United States and other countries. Unify detection and response across your security stack. Partner resources and information about our channel and technology partners. In order to create and use a Golden Ticket, an attacker needs to find a way into the network: The Golden Ticket attack is really clever but not trivial to execute. The user presents the TGT and requests a Ticket Granting Service (TGS) ticket. Sean Metcalf. The moniker comes from Roald Dahls bookCharlie and the Chocolate Factory,where a golden ticket is the highly coveted pass that gets its owner into Willy Wonkas tightly guarded candy factory. 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. There are two types of Kerberos tickets: Ticket Granting Ticket (TGT) and Service Tickets (ST). You can audit Kerberos AS and TGS events for discrepancies. This analytic identifies the execution of the Set-ADAccountControl commandlet with specific parameters. 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. 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. This request will generate a 4768 event with some unusual fields depending on the environment. 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. Finally, another strategy for flushing out Golden Ticket attacks is to create honeypot objects in Active Directory, such as a honeypot user account. According to the MITRE ATT&CK framework, these attacks involve the use of a Golden Ticket which, in this case, is a forged Kerberos ticket-granting ticket (TGT) to generate ticket granting service (TGS) tickets for any account in Active Directory. The name of the Kerberos requests and responses that are seen on the network are also highlighted (such as AS_REQ, AS_RSP, etc.). 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". What is a Golden Ticket Attack? When Kerberos is sent a TGT request with no preauthentication for an invalid username, it responds with KRB5KDC_ERR_C_PRINCIPAL_UNKNOWN or 0x6. Stand up to threats with real-time detection and fast response. Often, phishing emails are used to first gain access to the system. RC4-HMAC. Before being able to export tickets. How Kerberos authentication normally works 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). (n.d.). [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 most insidious part about this attack is you can change the password for the KRBTGT account, but the authentication token is still valid. With particular emphasis on Active Directory and Office 365 environments, Bryan specializes in Identity and Access Management, Data Governance, Migration, and Security, including Certified Information Systems Security Professional (CISSP) certification. Golden Ticket attacks give a threat actor unrestricted access to nearly everything in the targeted domain, including devices, folders, files, and domain controllers (DC). Multiple Disabled Users Failing To Authenticate From Host Using Kerberos. 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. Golden ticket can also be created offline. For each domain, change the KRBTGT account password once, force replication, and then change the password a second time. If AS is verified then the user gets a Kerberos Ticket Grant Ticket, or TGT, which is proof of authentication. Attackers will then investigate and gather intel like the domain name. Therefore, to invalidate all TGTs currently in the system, you need to reset the password twice. To be more precise - an attack that forges Kerberos Ticket Granting Tickets (TGT) that are used to authenticate users with Kerberos. Monitor the lifetime of TGT tickets for values that differ from the default domain duration. This technique is called AS-REP roasting and it effectively allows an attacker to perform an offline brute force attack against a users password. This behavior has been identified to assist with detecting PetitPotam, CVE-2021-36942. A Kerberos authentication ticket (TGT) was requested to identify one source endpoint trying to obtain an unusual number of Kerberos TGT tickets for non-existing users. 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. Useful Mimikatz parameters for creating Golden Tickets include: The following example creates a ticket for a fake user but provides the default administrator ID. Share it with them via. For those less familiar, a golden ticket is the name of a Kerberos ticket that is manually created by an attacker after gaining access to your environment's encryption "master key". There are two types of Kerberos tickets: Ticket Granting Ticket (TGT) and Service Tickets (ST). This analytic leverages Event Id 4768. 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. The newly-created TGT is encrypted and signed with a special account on the domain controller known as the Kerberos service (KRBTGT). This type of attack can fly under the radar and escape detection by automated security tools. * Correlate threat intelligence and forensics. 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. An endpoint requesting a large number of computer service tickets for different endpoints could represent malicious behavior like lateral movement, malware staging, reconnaissance, etc. As it stands, the digital identity surface is a dynamic one, still changing rapidly and requiring enterprises to adopt robust security solutions to protect user data. Despite the names innocent roots, a Golden Ticket attack can be devastating for the targeted enterprise if successfully carried out. Dont give end users admin authority on their workstations, and dont let admins log on to end-user computers. 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. A Kerberos authentication ticket (TGT) was requested to identify a TGT request with encryption type 0x17, or. Typically, on a regular Windows endpoint, only the lsass.exe process is the one tasked with connecting to the Kerberos Distribution Center to obtain Kerberos tickets. If the KDC prompts for authentication, the user is valid. Kerberos is an authentication protocol widely used in modern Windows domain environments. Enterprises bolstering their identity-based security trust SentinelOne to reduce their AD attack surface and protect against credential misuse through real-time infrastructure defense. This analytic leverages Event Id 4769, A Kerberos service ticket was requested, to identify an unusual TGS request where the Account_Name requesting the ticket matches the Service_Name field. Kerberos is the default authentication protocol used on Windows Active Directory networks since the introduction of Windows Server 2003. UsingPSExec,the attacker can open a session on the target domain controller; according to that session, they are now logged in as Administrator. This lab explores an attack on Active Directory Kerberos Authentication. Instead, theKerberos Key Distribution Center (KDC)functions as a trusted third-party authentication service. This analytic looks for a process accessing the winlogon.exe system process. Although TGT timestamps are not recorded in the Kerberos authentication logs, proper Active Directory security solutions are capable of monitoring them. If an attacker tries to use mimikatz to start working on their Golden Ticket, Varonis sends this alert during the attempt before its too late: Threat Model: Exploitation software created or modifiedHow it works: Varonis detects a file create or file modify operation for a file that matches a list of known hacker tools (i.e., mimikatz).What it means: An attacker has infiltrated the network and they are trying to establish further capability to move around undetected and steal data.Where it works: Windows, Unix, Unix SMB, SharePoint, NetApp, EMC, Hitachi NAS, HP NAS, SharePoint Online, One Drive, Dell FluidFS, Nasuni. Active Directory Golden Ticket attacks are very difficult to detect because Golden Tickets look like perfectly valid TGTs. Kerberos Pre-Authentication Flag Disabled in UserAccountControl. If you've already registered, sign in. 2015-2023, The MITRE Corporation. Retrieved March 17, 2020. To do that, hackers have a wide variety of tactics at their disposal; popular ones include phishing, spyware, brute force and credential stuffing. To reset the password, you must be a member of both the Domain Admins group and the local Administrators group, or have been delegated the appropriate authority. Get hands-on with ExtraHop's cloud-native NDR platform in a capture the flag style event.
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