How Privilege Escalation Works and 6 Ways to Prevent It

What Is Privilege Escalation? 

Privilege escalation is a security exploit or technique used by attackers — starting with compromised or stolen credentials — to gain unauthorized access to higher-level permissions or system privileges within a computer system, network, or application. 

It is typically achieved by exploiting vulnerabilities, misconfigurations, human error, or flaws in the system’s security design, allowing the attacker to gain control, access sensitive data, or perform unauthorized actions. 

Privilege escalation can occur both vertically (elevating from a lower to a higher privilege level) and horizontally (gaining access to resources or capabilities at the same privilege level that were not initially granted).

This is part of a series of articles about insider threats. 

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Why Is It Important to Prevent Privilege Escalation? 

Privilege escalation is typically executed by an adversary who is using a compromised identity (credential). These types of attacks are incredibly hard to detect and almost always evade common signatures and rules. The impact of a successful privilege escalation can be devastating, made worse by the fact that traditional detections are ineffective.

Preventing privilege escalation is crucial for several reasons:

• Protect sensitive data: Privilege escalation can lead to unauthorized access to confidential information, such as personal, financial, or business data, which can be exploited or leaked by malicious actors.
• Maintain system integrity: When an attacker gains higher-level privileges, they can manipulate, modify, or delete critical system files, configurations, or applications, which can cause system instability or malfunction.
• Prevent unauthorized actions: By preventing privilege escalation, you can limit attackers’ ability to perform unauthorized actions, such as creating new user accounts, installing malware, or altering security settings.
• Compliance and legal implications: Organizations must adhere to various regulations and industry standards that require proper security measures to be in place, including protection against privilege escalation. Failure to do so can result in penalties, legal actions, and reputational damage.
• Maintain operational continuity: A successful privilege escalation attack can disrupt business operations, leading to downtime, lost productivity, and potential revenue loss. Preventing such attacks helps maintain operational continuity and safeguards business processes.

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Privilege Escalation Attack Techniques 

Privilege escalation attacks can be categorized into two primary techniques: vertical (or elevation) and horizontal. Each technique aims to gain unauthorized access, but they differ in the scope and level of privileges targeted.

Vertical Privilege Escalation (Elevation of Privilege)

In vertical privilege escalation attacks, the attacker attempts to elevate their access rights from a lower level to a higher level, such as moving from a standard user account to an administrator or system-level account. 

This type of attack allows the attacker to gain more control over the system, access restricted resources, and perform actions that were not possible with their initial level of access. Common techniques for vertical privilege escalation include:

• Exploiting software vulnerabilities: Attackers may take advantage of unpatched software or operating system vulnerabilities to elevate their privileges.
• Misconfigurations: Poorly configured systems, services, or file permissions can provide opportunities for attackers to elevate their privileges.
• Social engineering: Attackers might deceive users into providing their privileged credentials or perform actions that lead to an escalation in privileges.

Horizontal Privilege Escalation

In horizontal privilege escalation attacks, the attacker aims to gain access to resources or capabilities at the same privilege level as their current account but that were not initially granted to them. 

The goal is to access another user’s data, resources, or restricted functionalities without elevating the attacker’s privilege level. Common techniques for horizontal privilege escalation include:

• Password attacks: Attackers may employ techniques such as password guessing, brute-force attacks, or keylogging to gain unauthorized access to another user’s account with the same privilege level.
• Session hijacking: Attackers can intercept, manipulate, or take over an existing user session to gain access to their resources.
• Exploiting application vulnerabilities: Flaws in application logic, authentication, or access control mechanisms can be exploited by attackers to access resources or functionalities that should be restricted to other users.
• Pass-the-hash: Attackers capture a password hash and pass it through for authentication and lateral access to other networked systems.
• Silver and Golden Ticket attacks: Golden Ticket attacks surrender complete control over the Active Directory (AD). Alternatively using a silver ticket, an attacker can create multiple ticket-granting service (TGS) tickets for a specific service without communicating with the domain controller (DC) on a network.

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How Privilege Escalation Attacks Work 

Privilege escalation attacks, whether horizontal or vertical, typically hinge on exploiting a vulnerability related to privilege management, such as system flaws, misconfigurations, or insufficient access controls exploitable in Kerberos, etc.

All accounts interacting with a system possess a certain level of privileges, whether the account holder is aware of them or not. Ordinary users are generally limited in their access to system databases, sensitive files, or other valuable information sources. This is why they might not even be conscious of their privilege limitations – unlike malicious actors, they have no need to access information beyond their designated scope.

To better grasp privilege escalation, it’s important to recognize the five key techniques attackers employ to obtain higher levels of rights or access: credential exploitation (e.g., leveraging weak passwords), system vulnerabilities and exploits, misconfigurations, malware, and social engineering.

By utilizing one or more of these methods, malicious actors can infiltrate a system. After gaining access, they will observe the environment, waiting for the right moment to initiate their next move—escalating privileges to accounts with more authority than the initially compromised one. Depending on their objectives, attackers may continue to increase their privileges to gain control over an administrator or root account or maintain horizontal movement until they ultimately dominate the entire environment.

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6 Ways to Prevent Privilege Escalation Attacks 

Preventing privilege escalation attacks requires a multifaceted approach that incorporates various security practices, tools, and measures. Here are best practices to consider:

1. Carefully manage privileged accounts

Here are several ways to adequately manage access and prevent privilege escalation:

• Limiting the number of privileged accounts: Reduce the number of privileged accounts to the minimum necessary, and only grant elevated permissions to users who require them.
• Least privilege principle: Assign the minimum level of access and permissions required for users to perform their tasks.
• Regularly reviewing and auditing: Periodically review and audit privileged account permissions to ensure that only authorized users have elevated access.
• Monitoring and logging: Implement monitoring and logging of privileged account activities to detect suspicious actions and potential abuse.
• Use of temporary credentials: Implement the use of temporary or time-limited credentials for privileged accounts, which expire after a certain period.

2. Patch and update software

Regularly patching and updating software, operating systems, and firmware is essential to address known vulnerabilities and reduce the risk of privilege escalation attacks. Develop a patch management process that includes:

• Monitoring for updates: Keep track of security patches and updates released by software vendors. Use automation of tools or processes wherever possible.
• Prioritizing patches: Prioritize patches based on the severity of vulnerabilities and the potential impact on your systems.
• Testing and deployment: Test patches in a controlled environment before deploying them to production systems to avoid potential compatibility issues or disruptions.
• SCA and SAST: Don’t forget software composition analysis and static application security testing. If you are using third-party web tools, make sure your libraries are up to date with the Dev team.
• Change tickets: Notify your Security Operations team when you make specific changes that may affect their function or vision across the organization.

3. Perform Vulnerability Scans

Regular vulnerability scanning helps identify potential weaknesses, misconfigurations, and vulnerabilities in your systems that could be exploited in a privilege escalation attack. Implement a vulnerability management program that includes:

• Regular scanning: Schedule vulnerability scans to run regularly on your systems and networks. This includes, as stated above, regular application security testing for vulnerabilities and known exploits in Developer tools (e.g. JexBoss, Apache Struts).
• Remediation: Establish a process for prioritizing and remediating identified vulnerabilities, based on their severity and potential impact. This can also include upgrading from LDAP to LDAPS, and NTLM to Kerberos wherever possible.
• Validation: Verify that vulnerabilities have been successfully remediated and that new vulnerabilities have not been introduced during the process.

4. Monitor Network Traffic and Behavior

Monitoring network traffic and user behavior can help detect potential privilege escalation attacks in progress or identify signs of unauthorized access. Implement network and behavior monitoring solutions, such as:

• Intrusion detection systems (IDS): Use IDS to monitor network traffic for signs of intrusion or malicious activity.
• Security information and event management (SIEM): Employ SIEM tools to collect, analyze, and correlate log data from various sources, helping to identify potential security incidents.
• User and entity behavior analytics (UEBA): Implement UEBA solutions to monitor and analyze user behavior for signs of unusual or suspicious activity that may indicate unauthorized access or privilege escalation attempts.

5. Enforce a Strong Password Policy

A strong password policy reduces the risk of unauthorized access and privilege escalation through password attacks. Ensure your password policy includes:

• Complexity: Require passwords to include a mix of upper and lowercase letters, numbers, and special characters.
• Length: Enforce a minimum password length, typically 12-16 characters.
• Password rotation: Set a password expiration period, requiring users to change their passwords regularly. Make sure they cannot repeat passwords for at least 3 cycles.
• Account lockout: Implement account lockout policies to lock accounts after a specified number of failed login attempts, reducing the risk of brute-force attacks.

6. Conduct Security Awareness Training

Educate your employees about the risks of privilege escalation attacks and the importance of following security best practices. Security awareness training should cover:

• Recognizing social engineering tactics: Train employees to identify and respond to phishing attempts, pretexting, and other social engineering tactics that could be used to gain unauthorized access.
• Safe password practices: Educate users about the importance of creating strong, unique passwords and never sharing them with others.
• Reporting suspicious activity: Encourage employees to report any unusual or suspicious activity they encounter, such as unexpected privilege changes or unauthorized access attempts.
• Following organizational security policies: Ensure that employees understand and adhere to your organization’s security policies and procedures, including those related to access control, software updates, and privileged account management.
• Regular training and updates: Conduct security awareness training on a regular basis and keep employees informed about emerging threats, vulnerabilities, and best practices to stay protected.

Learn more: Read our guide to detecting insider threatsbeam UEBA

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How Exabeam detects privilege escalation

Privileged activity, escalation, and abuse are three common indicators under the general use case categories of both Malicious Insider and Compromised Credentials. 

Signs and indicators are collated through signals from:

• Physical access controls
• Endpoint auditing
• Firewalls
• Access management systems
• Endpoint protections
• VPNs
• ID as a Service (SSO, etc.)
• PAM devices
• File sharing
• Email security
• And many more

Learn more about using Exabeam to prevent this attack in our blog Privilege Escalation Detection: The Key to Preventing Advanced Attacks