NTLM brute force attacks can pose a significant risk to your system’s security. In this section, we will explore the steps and tools you can use to effectively investigate and mitigate these attacks.
To investigate NTLM brute force attacks, there are several steps and tools that can be used. Firstly, the Varonis IR Team suggests detecting NTLM brute force attacks through alerts such as password spraying attacks, account enumeration attacks, multiple account lockouts, and abnormal behavior. They recommend using the Varonis Dashboard to search for failed NTLM authentications and investigate suspicious activity. Additionally, they provide instructions on how to enable NTLM auditing and investigate NTLM logs in Event Viewer.
Another source mentions that NTLM brute force attacks are a common type of attack and highlights the importance of detecting signs of account enumeration and password spraying. They describe the NTLM protocol, how it works, and why it is still in use despite its vulnerabilities. They also provide information on how to investigate NTLM brute force attacks using various tools and techniques such as credential dumping, SharpHound (an Active Directory collector tool), and analyzing NTLM logs.
The third source discusses the significance of account enumeration in NTLM brute force attacks and explains how the NTLM protocol works. It introduces Azure ATP as a tool that provides visibility into NTLM authentications and can detect the actual server accessed within the network. It also mentions the possibility of “unknown” devices appearing in Azure ATP alerts due to overwritten source device names.
Overall, to investigate NTLM brute force attacks, it is crucial to detect signs of account enumeration and password spraying, leverage tools such as Varonis, Event Viewer, SharpHound, and Azure ATP, and analyze NTLM logs and authentication data to identify the source devices and accessed servers involved in the attack.
Detecting NTLM Brute Force Attacks
Detecting NTLM brute force attacks requires a keen eye for indicators such as password spraying attacks, account enumeration attacks, and abnormal behavior. In this section, we will explore how you can effectively detect these attacks and stay one step ahead of the threat actors.
One method of detection is through analyzing patterns of failed login attempts. Password spraying attacks involve trying a few commonly used passwords against multiple accounts to avoid account lockouts. By monitoring for multiple failed login attempts from different accounts but with the same source IP address, you can identify potential password spraying attacks.
Account enumeration attacks, on the other hand, involve checking whether certain user accounts exist on a system. This is usually done through brute force methods, trying different usernames until a valid account is found. To detect such attacks, it’s important to monitor for repeated failed login attempts against different usernames but with the same source IP address.
| Indicators | Possible NTLM Brute Force Attack |
|---|---|
| Multiple failed login attempts from different accounts, same IP address | Password spraying attack |
| Repeated failed login attempts against different usernames, same IP address | Account enumeration attack |
| Unusual login times or access from unusual locations | Abnormal behavior |
Another red flag to watch out for is abnormal behavior. If you notice unusual login times or access from unfamiliar locations, it could indicate an ongoing NTLM brute force attack. Monitoring for these anomalies can help you spot and respond to attacks before significant damage occurs.
Summary:
- Monitor for multiple failed login attempts from different accounts but with the same source IP address to detect password spraying attacks.
- Keep an eye out for repeated failed login attempts against different usernames but with the same source IP address as a sign of account enumeration attacks.
- Pay attention to unusual login times or access from unfamiliar locations as potential indicators of abnormal behavior.
Investigating NTLM Brute Force Attacks
Once you’ve detected an NTLM brute force attack, it’s essential to investigate the incident thoroughly. In this section, we will guide you through the investigation process using tools like the Varonis Dashboard and Event Viewer to analyze NTLM logs and authentication data.
The Varonis IR Team suggests detecting NTLM brute force attacks through various indicators, including password spraying attacks, account enumeration attacks, multiple account lockouts, and abnormal behavior. To investigate further, they recommend utilizing the powerful features of the Varonis Dashboard. By searching for failed NTLM authentications and investigating suspicious activity, you can gain insight into the origins and methods of the attack.
To enable NTLM auditing and delve deeper into the attack, Event Viewer is a valuable tool. By examining NTLM logs, you can uncover valuable information about the attempted breaches and identify any patterns or anomalies. By analyzing this data, you can gather crucial evidence that will aid in further investigation and mitigation of NTLM brute force attacks.
Investigating NTLM brute force attacks requires a combination of tools and techniques. By leveraging the Varonis Dashboard and Event Viewer, you can effectively analyze NTLM logs and authentication data, unraveling the complexities of the attack. It is important to follow the step-by-step guide provided, enabling NTLM auditing and using the Varonis Dashboard to identify suspicious activity. With these tools at your disposal, you can enhance your system’s security and protect against future threats.
| Tools | Techniques |
|---|---|
| Varonis Dashboard | Search for failed NTLM authentications |
| Event Viewer | Analyze NTLM logs |
Tools and Techniques for Investigating NTLM Brute Force Attacks
Investigating NTLM brute force attacks requires the use of specialized tools and techniques. In this section, we will explore methods such as credential dumping, the use of SharpHound, and analyzing NTLM logs to gain valuable insights into the attack.
One effective technique in investigating NTLM brute force attacks is the practice of credential dumping. This involves extracting and analyzing credentials stored on a compromised system. By obtaining these credentials, investigators can trace the attacker’s steps and identify potential points of entry. Tools like Mimikatz and ProcDump can be used to dump credentials and capture the necessary data for analysis.
Another useful tool is SharpHound, an Active Directory collector that helps in identifying potentially compromised accounts and systems. It collects information such as group membership, local admin rights, and trust relationships, providing valuable insights into the attacker’s movements within the network. By analyzing the data collected by SharpHound, investigators can gain a clearer understanding of the attack and take appropriate action to mitigate further risk.
Furthermore, analyzing NTLM logs is crucial in understanding the scope and impact of an NTLM brute force attack. These logs can provide details about failed authentication attempts, suspicious activity, and potential sources of the attack. By carefully examining these logs in tools like Event Viewer, investigators can identify patterns, detect anomalies, and gather evidence to support their investigation.
| Tools and Techniques | Description |
|---|---|
| Credential Dumping | The practice of extracting and analyzing credentials stored on compromised systems to identify points of entry. |
| SharpHound | An Active Directory collector tool that helps identify compromised accounts and provides insights into the attacker’s movements. |
| Analyzing NTLM Logs | The examination of NTLM logs, using tools like Event Viewer, to identify patterns, anomalies, and potential sources of the attack. |
In conclusion, investigating NTLM brute force attacks requires the use of various tools and techniques. By employing credential dumping, SharpHound, and analyzing NTLM logs, investigators can gain valuable insights into the attack and take necessary steps to mitigate the risk. These methods, when used in combination, offer a comprehensive approach to investigating and responding to NTLM brute force attacks.
Leveraging Azure ATP for NTLM Brute Force Attack Investigation
Azure ATP can be a powerful ally in your efforts to investigate NTLM brute force attacks. In this section, we will explore how Azure ATP enhances account enumeration detection and offers valuable insights into the servers involved in the attack.
Account enumeration is a critical step for attackers in NTLM brute force attacks. By identifying valid usernames through methods like password spraying, attackers can then focus their efforts on compromising these accounts. Azure ATP provides advanced detection capabilities to identify account enumeration attempts, alerting you to potential threats in real-time. This proactive approach allows you to take swift action and mitigate the risk of a successful attack.
Furthermore, Azure ATP offers server visibility, helping you gain a deeper understanding of the scope and impact of an NTLM brute force attack. By analyzing authentication data, Azure ATP can pinpoint the servers accessed by the attacker, providing crucial information for your investigation. This visibility enables you to take appropriate measures, such as isolating compromised servers or strengthening their security measures.
It’s important to note that Azure ATP alerts may occasionally include “unknown” devices due to overwritten source device names. While this can temporarily complicate investigation efforts, it highlights the significance of Azure ATP in detecting and uncovering suspicious activities within your network.
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