What Is a Privilege Escalation Attack?
A privilege escalation attack is a type of network intrusion that exploits system vulnerabilities to gain higher access and permissions than initially granted. The purpose of the attack is to compromise system integrity, confidentiality, and availability, which usually involves accessing sensitive data or performing unauthorized tasks.
Privilege escalation highlights one of the most significant challenges in maintaining a secure digital environment—controlling who has access to what. This control becomes even more critical when the people seeking access have malicious intent.
This is part of a series of articles about cyber attack
How Does Privilege Escalation Work?
The process of privilege escalation involves exploiting a system’s vulnerabilities to gain unauthorized access. This is often achieved by manipulating the system’s flaws, misconfigurations, and at times, the human element of the security chain.
The attacker typically begins with low-level access, such as that of an ordinary user or a guest, and probes the system for vulnerabilities. Once a vulnerability is found, the hacker uses it to elevate their access level. To achieve privilege escalation, the hacker needs to understand the inner workings of the operating system, the applications running on it, and the network architecture.
There are two primary ways attacks can escalate privileges:
- Vertical privilege escalation, also known as privilege elevation, involves a lower-level user gaining higher-level privileges. For instance, a standard user account may acquire the permissions of an administrator, granting unrestricted control over the system.
- Horizontal privilege escalation occurs when a user gains the privileges of another user operating at the same level. An example is when one employee accesses another employee’s data without their permission. While this may not involve gaining higher-level privileges, it can still lead to unauthorized data access and potential misconduct.
Examples of Privilege Escalation Attack Vectors
Credential Exploitation
Credential exploitation involves attackers tricking users into revealing their login information, often through phishing attempts, and use these credentials to gain unauthorized access to the system.
What makes these types of attacks particularly dangerous is their ability to bypass most security measures. Since the attacker is using legitimate credentials, they can often evade detection systems that are designed to spot unauthorized access.
Learn more in our detailed guide to credential stuffing
Vulnerabilities and Exploits
Software vulnerabilities and exploits are another common attack vector for privilege escalation. This involves the attacker taking advantage of a software flaw, bug, or vulnerability to gain unauthorized access or increase their privileges.
Software developers often release patches to fix these vulnerabilities, but not all users install these updates promptly. This delay creates a window of opportunity for hackers to exploit these vulnerabilities.
Misconfigurations
Misconfigurations are an often-ignored attack vector, but they can be just as dangerous as software vulnerabilities. Misconfigurations can happen at any level—from the operating system and network devices to application settings.
Such misconfigurations can provide an attacker with an easy way to escalate their privileges. For instance, a file with incorrect permissions could allow a low-privilege user to modify it, potentially leading to a privilege escalation.
Malware
Malware is another common tool used in privilege escalation attacks. Many types of malware, such as Trojans and rootkits, are designed to exploit system vulnerabilities and escalate privileges.
Once the malware is installed, it can perform a variety of malicious activities, from stealing sensitive data to controlling the system. It’s also common for malware to create backdoors, allowing the attacker to maintain their access even after the initial vulnerability is patched.
Social Engineering
Social engineering is a potent tool for privilege escalation. This involves manipulating individuals into revealing sensitive information or performing actions that compromise security.
In a typical social engineering attack, the attacker might impersonate a trusted individual or organization to trick the victim. Once the victim trusts the attacker, they can be manipulated into revealing their credentials, installing malware, or even directly elevating the attacker’s privileges.
Windows and Linux Privilege Escalation Techniques
Privilege Escalation in Windows
Here are some privilege escalation techniques specific to Windows environments:
- Registry hacks: The Windows Registry contains configuration settings that can be manipulated for privilege escalation. For example, an attacker might change registry keys related to user account control (UAC) settings to lower security barriers.
- File system access: Gaining write access to system files or directories can lead to privilege escalation. An attacker might replace a system binary with a malicious version, which is subsequently executed with higher privileges.
- Token manipulation: Windows has built-in tools like PsExec or Accesschk which can be misused. Attackers might use these tools to manipulate process tokens and impersonate other users or system accounts.
- Service misconfigurations: Poorly configured Windows services can be exploited. An example is when a service is set to run with high privileges but allows unprivileged users to modify its executable path.
Privilege Escalation in Linux
Here are some privilege escalation techniques specific to Linux environments:
- Kernel exploits: Certain versions of Linux have known kernel vulnerabilities. Attackers may exploit these to execute code at the kernel level, gaining complete control over the system.
- Driver vulnerabilities: Linux drivers, particularly third-party ones, can have security flaws that allow privilege escalation when exploited.
- Sudo misconfigurations: Incorrect sudo configurations can allow a user to execute commands with root privileges. An attacker might exploit a misconfigured sudoers file to run privileged commands.
- File permission weaknesses: Inappropriately set file permissions on critical files or directories can lead to privilege escalation. For example, a writable password file can allow an attacker to add a new root account.
- Cron jobs: Misconfigured cron jobs running as root can be exploited. An attacker could replace a script executed by a cron job with their malicious script.
- Process hijacking: Attackers might hijack processes running with higher privileges by exploiting weaknesses in how they handle inputs or resources.
- Environment variables: Manipulating environment variables like PATH or LD_LIBRARY_PATH can trick a system into executing malicious code with elevated privileges.
Best Practices to Prevent Privilege Escalation Attacks
In the face of these threats, adopting best practices can significantly reduce the risk of privilege escalation attacks.
Apply the Least Privilege Principle
The principle of least privilege (PoLP) is a computer security concept in which a user is given the minimum levels of access necessary to complete their job functions. This approach can significantly mitigate the risk of privilege escalation attacks. If a user account is compromised, the attacker’s activities will be limited to the permissions of that particular account.
Use Strong Authentication Methods
One of the first lines of defense against privilege escalation attacks is the implementation of strong authentication methods. Multi-factor authentication (MFA) is a highly effective approach. MFA requires users to provide at least two means of identification before they can access a system. These methods typically involve something you know (password), something you have (security token), and something you are (biometric data). By using MFA, it becomes significantly more challenging for an attacker to gain unauthorized access to an account or system.
Implement Strong Passwords
Many organizations are transitioning to passwordless authentication. But as long as passwords are used, they should be long, complex, and unique, combining uppercase and lowercase letters, numbers, and special characters. Passwords should also be changed regularly, and password reuse should be discouraged. Implementing a password manager can assist in managing complex passwords across multiple accounts.
Scan for Vulnerabilities
To protect against privilege escalation attacks, it’s essential to identify and rectify any vulnerabilities in your system. Regular vulnerability scanning can help achieve this. These scans can identify potential weaknesses in your system that could be exploited by attackers. Once found, these vulnerabilities should be prioritized for remediation based on their potential impact.
Monitor User Activity
Monitoring user activity on your network can help detect suspicious behavior that might indicate an attempted privilege escalation attack. By keeping an eye on user activities, you can quickly identify unusual behavior, such as a user attempting to access resources beyond their permission level or changing system settings. Anomalies should be examined immediately to determine if they represent a security threat.
Use Anomaly Detection Tools
Anomaly detection tools can be a powerful weapon in your arsenal against privilege escalation attacks. These tools use AI and machine learning algorithms to learn the ‘normal’ behavior of users and systems on your network. When anomalous behavior is detected, these tools can send an alert for further investigation. This allows for quick detection and response to potential privilege escalation attacks.
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