COMMON ATTACK PATTERN ENUMERATION AND CLASSIFICATIONLive MITRE record

CAPEC-652

Use of Known Kerberos Credentials

An adversary obtains (i.e. steals or purchases) legitimate Kerberos credentials (e.g. Kerberos service account userID/password or Kerberos Tickets) with the goal of achieving authenticated access to additional systems, applications, or services within the domain.

Abstraction

Standard

Typical severity

High

Likelihood of attack

Medium

Understand the attack

What is this attack pattern?

An adversary obtains (i.e. steals or purchases) legitimate Kerberos credentials (e.g. Kerberos service account userID/password or Kerberos Tickets) with the goal of achieving authenticated access to additional systems, applications, or services within the domain.

Extended description

Kerberos is the default authentication method for Windows domains and is also used across many operating systems. Attacks leveraging trusted Kerberos credentials can result in numerous consequences, depending on what Kerberos credential is stolen. For example, Kerberos service accounts are typically used to run services or scheduled tasks pertaining to authentication. However, these credentials are often weak and never expire, in addition to possessing local or domain administrator privileges. If an adversary is able to acquire these credentials, it could result in lateral movement within the domain or access to any resources the service account is privileged to access, among other things. Ultimately, successful spoofing and impersonation of trusted Kerberos credentials can lead to an adversary breaking authentication, authorization, and audit controls with the target system or application.

Execution flow

How does the attack proceed, step by step?

1

Explore

Acquire known Kerberos credentials

The adversary must obtain known Kerberos credentials in order to access the target system, application, or service within the domain.

Techniques used

  • An adversary purchases breached Kerberos service account username/password combinations or leaked hashed passwords from the dark web.
  • An adversary guesses the credentials to a weak Kerberos service account.
  • An adversary conducts a sniffing attack to steal Kerberos tickets as they are transmitted.
  • An adversary conducts a Kerberoasting attack.
2

Experiment

Attempt Kerberos authentication

Try each Kerberos credential against various resources within the domain until the target grants access.

Techniques used

  • Manually or automatically enter each Kerberos service account credential through the target's interface.
  • Attempt a Pass the Ticket attack.
3

Exploit

Impersonate

An adversary can use successful experiments or authentications to impersonate an authorized user or system, or to laterally move within the domain

Spoofing

Malicious data can be injected into the target system or into other systems on the domain. The adversary can also pose as a legitimate domain user to perform social engineering attacks.

Data Exfiltration

The adversary can obtain sensitive data contained within domain systems or applications.

Requirements

What does the attack require?

Prerequisites

  • The system/application leverages Kerberos authentication.
  • The system/application uses one factor password-based authentication, SSO, and/or cloud-based authentication for Kerberos service accounts.
  • The system/application does not have a sound password policy that is being enforced for Kerberos service accounts.
  • The system/application does not implement an effective password throttling mechanism for authenticating to Kerberos service accounts.
  • The targeted network allows for network sniffing attacks to succeed.

Skills required

  • Low: Once an adversary obtains a known Kerberos credential, leveraging it is trivial.

Resources required

  • A valid Kerberos ticket or a known Kerberos service account credential.

Detection

What are the indicators of the attack?

Authentication attempts use expired or invalid credentials.
Authentication attempts are originating from IP addresses or locations that are inconsistent with an account's normal IP addresses or locations.
Data is being transferred and/or removed from systems/applications within the network.
Suspicious or Malicious software is downloaded/installed on systems within the domain.
Messages from a legitimate user appear to contain suspicious links or communications not consistent with the user's normal behavior.

Impact

What does a successful attack lead to?

Gain Privileges

Affected scopes: Confidentiality, Access Control, Authentication

Read Data

Affected scopes: Confidentiality, Authorization

Modify Data

Affected scopes: Integrity

Defence

How is it prevented and mitigated?

1
Create a strong password policy and ensure that your system enforces this policy for Kerberos service accounts.
2
Ensure Kerberos service accounts are not reusing username/password combinations for multiple systems, applications, or services.
3
Do not reuse Kerberos service account credentials across systems.
4
Deny remote use of Kerberos service account credentials to log into domain systems.
5
Do not allow Kerberos service accounts to be a local administrator on more than one system.
6
Enable at least AES Kerberos encryption for tickets.
7
Monitor system and domain logs for abnormal credential access.

Real world

MITRE example instances

Example instance 1Detail
Bronze Butler (also known as Tick), has been shown to leverage forged Kerberos Ticket Granting Tickets (TGTs) and Ticket Granting Service (TGS) tickets to maintain administrative access on a number of systems. [ REF-584 ]
Example instance 2Detail
PowerSploit's Invoke-Kerberoast module can be leveraged to request Ticket Granting Service (TGS) tickets and return crackable ticket hashes. [ REF-585 ] [ REF-586 ]
CAPEC-652: Use of Known Kerberos Credentials — DayBreach Saldırı Sözlüğü · DayBreach