What is a golden ticket attack?

Golden ticket attacks are when criminals infiltrate the Kerberos authentication system. They are a serious cybersecurity threat, especially for organizations using Microsoft Active Directory (AD) to manage user identities. These attacks take advantage of weaknesses in Kerberos, allowing attackers to gain extensive access to an organization’s network.

Understanding golden ticket attacks

Kerberos is an authentication system that uses cryptography and key distribution to authenticate users. However, if attackers find a way to interfere with this process, they can forge a TGT and move freely within the network, potentially compromising sensitive data and systems.

In one of these sophisticated attacks, hackers create a fake Kerberos Ticket Granting Ticket (TGT) to get unauthorized access. This fake TGT acts like a master key, allowing attackers to access sensitive areas of the network, including files, databases, and user accounts, with almost no restrictions.

The impact of remote work on security

With more people working remotely and cloud-based solutions becoming the norm, organizational networks are more exposed to potential vulnerabilities. Remote work creates new openings for attacks, with employees accessing corporate systems from various devices and locations. In this environment, golden ticket attacks become a bigger risk, as attackers can exploit compromised credentials to penetrate critical systems.

Read also: Cybersecurity challenges of remote working 

Where did golden ticket attacks come from?

The concept of golden ticket attacks is closely tied to the open-source tool Mimikatz, created in 2011. Mimikatz was initially intended to highlight vulnerabilities in Microsoft Windows, particularly around handling user credentials. The tool can extract sensitive information, such as usernames, passwords, and Kerberos tickets, making it a valuable tool for attackers.

The name “golden ticket” is inspired by Charlie and the Chocolate Factory, where a golden ticket grants special access. Similarly, in cybersecurity, a golden ticket gives attackers a way to bypass security measures and gain unauthorized access to an organization’s network.

How does a golden ticket attack work?

To understand a golden ticket attack, it helps to know the basics of the Kerberos system. Kerberos includes several main parts: the key distribution center (KDC), the ticket-granting server (TGS), and the ticket-granting ticket (TGT), which serves as proof of a user’s identity.

Steps in a golden ticket attack:

• Gaining access: Attackers first break into the network, often through phishing, exploiting vulnerabilities, or similar tactics. Once inside, they start analyzing the network structure.
• Stealing credentials: Attackers use tools like Mimikatz to extract hash code from a compromised system. The hash is fundamental because it’s used to create valid TGTs across the network.
• Creating the golden ticket: With the hash, attackers can forge a TGT, also called a "golden ticket." This forged ticket effectively provides them with unrestricted access to the network.
• Exploiting access: Armed with this golden ticket, attackers can freely move through the network, accessing sensitive data, creating new tickets, and remaining undetected for long periods.

Read more: What is a phishing attack? 

Detecting golden ticket attacks

These attacks are hard to spot because they’re designed to slip past standard security measures. However, certain strategies can help identify them.

• Monitoring authentication requests to the KDC can be effective; unusual patterns, like repeated TGT requests from a single source, might suggest malicious activity. 
• Anomaly detection tools can also analyze user behavior for sudden, out-of-the-ordinary access requests. 
• Security information and event management (SIEM) systems can flag unusual activities, such as a single account creating multiple tickets, allowing security teams to respond quickly.

Preventing golden ticket attacks

Preventing these attacks requires a combination of technology and security best practices, such as:

• Adopting a zero-trust model, where all users and devices are continuously verified
• Limiting access based on the principle of least privilege ensures users only have access to resources needed for their roles, which minimizes potential attack paths. 
• Strengthening credential management is also necessary; enforcing strong password policies and conducting phishing awareness training can help prevent unauthorized access.
• Proactive monitoring, including threat hunting and behavioral analytics. Skilled threat hunters can uncover stealthy attacks that automated systems might miss, and behavioral analytics can identify unusual patterns in user activity that may indicate a breach.

In the news

The NSA and its Five Eyes partners are urging businesses to secure Microsoft’s Active Directory (AD) since it’s widely used for managing access to company networks. AD has become a top target for hackers, especially through methods like Golden Ticket attacks, where attackers create fake access tickets that give them long-term control over the system. Critics say Microsoft’s tools aren’t enough to catch these attacks, and the NSA suggests using tools like BloodHound to get a better view of AD’s structure. AD’s complex setup often leaves gaps, making it easier for hackers to move through systems, stay hidden, and gain more control.

FAQs

What is a key distribution center (KDC)?

A key distribution center (KDC) is a service that issues tickets to authenticate users and devices in a secure network.

What is a ticket-granting server (TGS)?

A ticket-granting server (TGS) is part of the KDC that provides service tickets to users so they can access specific resources on the network.

What is a ticket granting ticket (TGT)?

A ticket granting ticket (TGT) is a token issued by the KDC to a user once their identity is verified, allowing them to request access to network resources.

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