What Is Privilege Escalation? How to Detect and Prevent Privilege Escalation Attacks in Windows

Organizations usually rely on remote work capabilities, leading them to use cloud systems. But with increased use of cloud infrastructure, the vulnerability to cyberattacks increases. One such is the Privilege Escalation attack, a complex threat to any network.

Multiple defense strategies are required to detect and prevent privilege escalation attacks, but understanding what this attack means is important even before that.

So, in this blog, we’ll explain what is privilege escalation attack, how it can be detected and its best prevention practices.

Let’s begin!

What Is Privilege Escalation?

Privilege escalation is a serious threat that many businesses face because they sometimes overlook managing permission levels properly. This means that security measures may not be strong enough to stop these attacks.

During privilege escalation attacks, a malicious actor gains access to an employee’s account by bypassing the usual authorization process. Attackers usually do this to steal data, disrupt business operations, or create hidden access points.

These actions can seriously disrupt business operations, which is why it’s crucial to include them in any business continuity plan.

If your business faces a privilege escalation attack, how you react is extremely important.

Here are some questions to consider:

• What did the attacker have authorization and access to?
• How are business services currently impacted?
• What other activities occurred on this account during the attack?

How do Privilege Escalation Attacks Work?

Privilege escalation attacks typically rely on exploiting weaknesses in privilege management, whether they move horizontally or vertically. These weaknesses could include system flaws, misconfigurations, or insufficient access controls, which can be exploited through Kerberos vulnerabilities.

Every account interacting with a system has some privileges, even if the account holder isn’t aware of them.

• Regular users usually have limited access to system databases, sensitive files, or other valuable information.
• Unlike attackers who aim to access information beyond their allowed scope, they might not realize these limitations.

Understanding privilege escalation involves recognizing five main techniques attackers use to gain higher levels of rights or access:

• Credentials Exploitation (like using weak passwords)
• Exploiting System Vulnerabilities
• Misconfigurations
• Malware
• Social Engineering

Attackers can breach a system by employing one or more of these techniques. Once inside, they’ll assess the environment, waiting for the right moment to advance—escalating privileges to accounts with more authority.

Depending on their goals, attackers might continue increasing their privileges to take control of an administrator or root account or move horizontally to dominate the entire system.

Types of Privilege Escalation

Primarily, there are 2 main ways that attacks can escalate privileges;

Horizontal Privilege Escalation

Regarding horizontal privilege escalation attacks, the attacker focuses on accessing resources or capabilities at the same privilege level as their current account but which were not originally granted to them. The ultimate goal is to access another user’s data, resources, or some restricted functionalities without increasing the attacker’s privilege level.

Common Techniques for Horizontal Privilege Escalation include:

• Attackers use brute-force attacks, such as password guessing or keylogging, to gain unauthorized access to the user’s account.
• They also use silver and golden ticket attacks, where the golden ticket allows them to gain complete control over the Active Directory.
  
  Alternatively, with a silver ticket, attackers can create multiple TGS (ticket-granting service) tickets for a specific service without even communicating with the domain controller (DC) on a network.
• With pass-the-hash, attackers capture a password hash and use it for authentication to gain lateral access to other networked systems.
• Further, exploiting application vulnerabilities, likeflaws in application logic, authentication, or access control mechanisms, to access resources and functionalities that should be restricted to other users.
• Session hijacking is also there. Attackers intercept, manipulate, or take over an existing user session to access their resources.

Vertical Privilege Escalation

In vertical privilege escalation attacks, the attacker tries to raise their access rights from a lower level to a higher one. For example, they may aim to go from a regular user account to an administrator or system-level account.

This attack lets the attacker gain more control over the system, access restricted resources, and carry out actions that were impossible with their original level of access.

Common Techniques for Vertical Privilege Escalation include:

• Attackers exploit software or OS vulnerabilities that haven’t been patched, allowing them to increase their privileges.
• Poorly configured systems, services, or file permissions allow attackers to escalate their privileges.
• They also use social engineering to get privileged credentials or perform actions that lead to elevated privileges.

Examples of Privilege Escalation Techniques

Windows Sticky Keys Attack

When performing an attack on Windows computers, attackers sometimes may use a “sticky key” exploit, where they don’t require sophisticated technical knowledge. However, they require physical access to the target system and the ability to boot from a repair disc.

Here’s how the attack works:

• The attackers boot the system from a repair disc and enter the command prompt. To build a backup, copy the sethc.exe file from %systemroot%\system32.
• Then, they replace sethc.exe with a copy of cmd.exe from the same directory. Rename the cloned cmd.exe to sethc.exe.
• Now, they reboot the machine and, at the login screen, enable the “sticky keys” by pressing the Shift key 5 times. This will generate a command prompt with system-level access.
• Further, using this elevated access, attackers can create a backdoor into the system by creating a local administrator account, retaining access even after the attack.

This is how attackers can exploit system vulnerabilities and weaknesses to gain unauthorized access and potentially escalate privileges within a Windows environment.

Process Injection

Another approach for escalating privileges is process injection, which is especially useful when targeting weak processes. The Process Injector is a popular tool for this type of penetration testing. It can list all currently running processes on a system and identify the account running on each system.

This requires access to an account with higher permission levels. After identifying the target process (for example, cmd.exe), the attacker uses the Process Injector tool to execute a command specifying the process to inject into, the target account’s Process ID, and any additional required arguments.

Misconfigurations

Often overlooked, misconfigurations can represent considerable dangers as an attack vector, similar to software vulnerabilities. These can occur at multiple levels, such as the network devices, operating system, and application settings.

These further can provide a simple way for attackers to elevate their privileges. So, identifying and correcting these misconfigurations is necessary to maintain a safe environment and prevent privilege escalation attacks.

Android and Metasploit

Another popular tool is Metasploit, a popularly used tool among hackers that contains a collection of known exploits. Attackers, when targeting Android devices, this tool can be used against the rooted devices.

After attackers root an Android device, an SU binary becomes available, enabling commands to be executed as root.

Windows Sysinternals

After accessing a system via methods like the “Sticky Keys” attack, they can escalate the privileges further to gain full system access using the Sysinternals tool suite. This is a typical method for privilege escalation on Windows systems.

This method requires the Psexec commands and local administrator privileges on the system. Attackers can use a backdoor account with the command “psexec.exe -s cmd” and the psexec.exe program to elevate their privileges to system access.

Linux Passwd User Enumeration

In Linux systems, a basic privilege escalation attack involves enumerating user accounts on the machine. Attackers typically gain access to the shell of the system, often through misconfigured FTP servers.

Once access to the shell is obtained, attackers use the command “cat /etc/passwd | cut -d: -f1” to list all users on the machine.

Why Is It Important to Prevent Privilege Escalation?

An adversary often executes privilege escalation while utilizing a compromised identity (credential). These attacks are extremely complex to detect and almost always avoid conventional signatures and regulations.

A successful privilege escalation can have disastrous consequences exacerbated by the ineffectiveness of existing detection methods.

Preventing privilege escalation is critical for various reasons:

• To protect sensitive data as privilege escalation can result in unauthorized access to confidential information, such as financial, personal, or corporate data, which attackers can exploit or disclose.
• For compliance and legal implications, organizations must follow numerous rules and industry standards that need effective security measures, such as protection against privilege escalation. Failure to do so may result in sanctions, legal action, and reputational damage.
• To maintain operational continuity and company processes, a successful privilege escalation attack can disrupt business operations, resulting in reduced productivity, downtime, as well as potential financial loss.
• To prevent unauthorized actions, block privilege escalation. This will limit attackers’ ability to perform unauthorized actions such as installing malware, creating new user accounts, or changing security settings.
• To maintain system integrity. When attackers acquire elevated access, they can manipulate, edit, or remove vital system data, configurations, or applications, resulting in system instability or malfunction.

How to Prevent a Privilege Escalation Attack?

Perform Vulnerability Scans

Regularly scanning the systems to identify gaps, misconfigurations, and vulnerabilities could prevent the privilege escalation attack. For that, create a vulnerability scan management plan as:

• Schedule regular vulnerability scans for your networks and systems. As indicated, this includes regular application security testing for vulnerabilities and other exploits in developer tools like Apache Struts, JexBoss, etc.
• Create a strategy to prioritize and resolve detected vulnerabilities as per their severity and impact on the system. This might also include switching from LDAP to LDAPS and NTLM to Kerberos, wherever possible.
• At last, ensure all vulnerabilities are successfully resolved, and no new ones are introduced in the meantime.

Carefully Manage Privileged Accounts

Here are a few approaches to effectively manage access and prevent privilege escalation:

• Periodically check and audit privileged account permissions.
• Assigning the least degree of access and permissions that users need to complete their tasks.
• Reduce the number of privileged accounts and only provide access to people who need it.
• Use temporary credentials that expire after a set time.
• Implement logging and monitoring of privileged account activity to detect misuse and suspicious behavior.

Implement a Strong Password Policy

Setting a strong password somehow reduces the risk of unauthorized access as well as privilege escalation via password attacks. So, while creating a new password, make sure it:

• Is a minimum of 12 to 16 characters
• It should be a combination of uppercase and lowercase letters, numbers, and some special characters

Also, make sure to set an expiration date for a password so that users change it regularly and cannot repeat it more than three times.

Additionally, implement policies that lock accounts after various failed login attempts lowering the danger of brute-force attacks.

Patch and Update the Program

To address known vulnerabilities and issues and to limit the risk of privilege escalation attacks, regular patching and updating software, OS, and hardware is essential. For that, create a patch management plan which can:

• Keep track of the security patches and updates issues by software manufacturers.
• Prioritize patches as per the severity of vulnerabilities and their impact on the system.
• Test patches in a controlled environment before deploying them to production systems to avoid disruptions and compatibility issues.
• Never overlook composition analysis of software or static application security testing.
• With the third-party web tools, make sure your libraries are in sync with the developer team.
• Automate tools and processes whenever possible.

Conduct Security Awareness Training

Proper security awareness training should be provided to the staff to make them aware of the dangers of privilege escalation attacks. This way they will also know why to adopt security best practices.

• Education on using strong, unique passwords and restricting them from sharing with others.
• Train them to recognize as well as respond to pretexting, phishing, and other social engineering strategies that could be used to acquire unauthorized access.
• Encourage them to report strange or suspicious activity they see, including unexpected privilege changes or any unauthorized access attempts.
• Conduct regular security awareness training and update personnel about vulnerabilities, emerging threats, and best practices to stay safe.
• Ensure the staff understand and follow the organization’s security rules and procedures, like governing access control, software updates, etc.

Monitor Network Traffic and Behavior

To further aid in detecting some active privilege escalation attacks or to identify evidence of unauthorized access, monitoring network traffic and user behaviour is the key.

Some of the network and behavioural monitoring solutions include:

• IDS (Intrusion Detection Systems) to examine network data for indications of intrusion or malicious behaviour
• Use SIEM systems to analyze and relate log data from different sources to detect security issues
• Use UEBA systems to further monitor and analyze the behaviour for signals of suspicious activities indicating unauthorized access or privilege escalation.

Windows Least Privilege Management Best Practices to Follow

Use Strong Authentication Methods

Strong authentication mechanisms are a primary defense against privilege escalation threats. Multi-factor authentication (MFA) is a very successful method. MFA demands users to give at least two forms of identity before accessing a system.

These approaches usually involve something you know (password), something you have (security token), and something you are (biometric information). Using MFA makes it much more difficult for an attacker to obtain unauthorized access to an account or system.

Apply the Least Privilege Principle

The principle of least privilege is basically a computer security concept where a user is granted the least access required to perform their job tasks. This strategy considerably reduces the possibility of privilege escalation attacks. If a user account is compromised, the attacker’s activities are limited to the permissions granted to that account.

Implement Strong Passwords

Many organizations are implementing passwordless authentication. However, as long as passwords are used, they should be long, difficult, and unique, containing uppercase and lowercase letters, digits, and special characters.

Passwords should be updated regularly, and reuse should be discouraged. Implementing a password manager might help you manage complex passwords for various accounts.

Scan for Vulnerabilities

To protect against privilege escalation attacks, you must first identify and address any system vulnerabilities. Regular vulnerability scanning can help with this.

These scans might uncover potential vulnerabilities in your system that attackers could exploit. Once identified, these vulnerabilities should be prioritized for remedy depending on their potential effect.

Monitor User Activity

Monitoring user activity on your network can help you detect suspicious behavior that may signal an attempted privilege escalation attack.

You may rapidly detect anomalous behavior, such as a user attempting to access resources outside their permission level or changing system settings. Anomalies should be investigated immediately to see whether they pose a security risk.

Use Anomaly Detection Tools

Anomaly detection tools can be an effective defense against privilege escalation attempts. These products employ AI and machine learning algorithms to learn the ‘typical’ behavior of people and services on your network.

When these tools discover aberrant behavior, they can generate an alert to prompt additional inquiry. This enables timely detection and reaction to any privilege escalation attacks.

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