Understanding Privilege Escalation: A Critical Threat in Cybersecurity

Introduction

In the realm of cybersecurity, one of the most concerning threats that organisations face is privilege escalation. This insidious tactic allows attackers to elevate their level of access within a system or network, potentially granting them unprecedented control and the ability to wreak havoc on sensitive data and resources. Examples of elevated access include:

• Local/Domain administrator.
• SYSTEM/root-level access.
• User accounts with admin-like access.
• User accounts with access to a specific system or to perform specific functions.

Introduction to Privilege Escalation

Privilege escalation is a cybersecurity term referring to the process by which an attacker gains higher levels of access or permissions on a system or network than they are supposed to have. This unauthorised elevation of privileges allows the attacker to perform actions and access resources that are typically restricted to users with higher levels of authority, such as administrators or system owners.

In simpler terms, privilege escalation enables an attacker to "level up" their access within a system, potentially granting them the ability to manipulate data, install malware, steal sensitive information, or disrupt system operations.

Privilege escalation can occur through various means, including exploiting software vulnerabilities, misconfigurations, weak access controls, or social engineering tactics. It is a critical security concern for organisations because it can lead to significant breaches and compromises of sensitive data and resources.

Preventing privilege escalation involves implementing robust security measures such as:

• Regular software updates
• Strong access controls
• Monitoring for suspicious activities
• User awareness training

Types of Privilege Escalation

Privilege escalation can occur in different forms, each with its own characteristics and implications. Here are the main types of privilege escalation:

1. Vertical Privilege Escalation
2. Horizontal Privilege Escalation

Vertical Privilege Escalation: Vertical privilege escalation, also known as a privilege elevation attack, involves an increase of privileges/privileged access beyond what a user, application, or other asset already has. This entails moving from a low level of privileged access to a higher level of privileged access. Achieving vertical privilege escalation could require the attacker to perform several intermediary steps (i.e., execute a buffer overflow attack, etc.) to bypass or override privilege controls, or exploit flaws in software, firmware, the kernel, or obtain privileged credentials for other applications or the operating system itself.

Horizontal Privilege Escalation: Horizontal privilege escalation involves an attacker abusing the legitimate user's privileges to expand their permissions after unauthorised entry into the network. Typically, the attacker gains initial access to the user's account through a phishing campaign. Subsequently, the attacker leverages additional hacking tools like Metasploit to pinpoint system vulnerabilities or exploit common weaknesses such as outdated software. In either scenario, the attacker operates at a level of access capable of inflicting significant harm on the organisation's operations and reputation.

Each type of privilege escalation presents unique challenges and requires tailored security measures to mitigate the risks.

Importance of Preventing Privilege Escalation Attacks

Privilege escalation is a crucial tactic for attackers, providing them a pathway to infiltrate environments, establish persistence, deepen their access, and carry out more damaging malicious activities. For instance, a simple malware infection can escalate into a catastrophic data breach due to privilege escalation.

Attackers leverage privilege escalations to open new avenues for attack on target systems. This can involve various actions, such as gaining access to interconnected systems, deploying additional malicious payloads, modifying security configurations or privileges, enrolling in extreme cases, and attaining root access to a system or entire network.

Security teams need to recognise the signs of privilege escalation, which may include the presence of malware on sensitive systems, suspicious login activities, and abnormal network communications. The most common tools an attacker uses are NetExec (CrackMapExec), Metasploit, Powerview, SharpView, etc., and the security teams should flag these activities as soon as they are detected. Upon suspecting privilege escalation, conducting a thorough investigation is imperative.

Every instance of privilege escalation must be treated as a severe security incident, potentially requiring the organisation to report it to regulatory authorities based on their compliance obligations. Prompt and decisive action is crucial to mitigate the impact of such incidents and safeguard organisational assets and integrity.

Privilege Escalation Attack Example

After initial access to a network, attackers always look for vulnerabilities that allow for privilege escalation exploits, such as misconfigurations, software vulnerability, weak access controls, etc. The following example provides detailed information on privilege escalation from an Active Directory misconfiguration:

Active Directory Certificate Services (AD CS) Misconfiguration:

Active Directory Certificate Services (AD CS) is a server role that allows a corporation to build a public key infrastructure. This allows the organisation to provide public key cryptography, digital certificates, and digital signature capabilities to the internal domain.

Misconfigurations in certificate templates can enable attackers to escalate their privileges within the domain. These misconfigurations include granting low-privileged users enrolment rights, disabling manager approval, not requiring authorised signatures, and having overly permissive certificate template security descriptors. Additionally, misconfigured certificate templates that allow unprivileged users to specify a Subject Alternative Name (SAN) in their certificate requests can lead to unauthorised domain authentication.

To exploit the most common AD CS misconfiguration (i.e., ESC1), we need the Template to meet certain criteria:

• Enrolment Rights are set for the group our user belongs to so that we can request a new certificate from the Certificate Authority (CA).
• Extended Key Usage: Client Authentication means the generated certificate based on this template can authenticate to the domain computers.
• Enrolee Supplies Subject set to True, which means we can supply SAN (Subject Alternate Name)
• No Manager Approval is required, which means the request is auto-approved.

The ADCS misconfiguration ESC1 attack looks like the following:

• Run a certificate enumeration tool against the domain controller to find any vulnerable templates:

From the above image, enrolment rights are set for Domain Users, Enrolee Supplies Subject is set to True, and Extended Key Usage has Client Authentication.

• Request a certificate and supply the Administrator’s SAN (Subject Alternate Name).

1. ca: Certificate Authority
2. target: CA Hostname
3. Template: Name of the vulnerable Template (MDM_User in this case)
4. upn: Target Username (DefaultAdmin in this case)
5. dns: DNS Server

• Split certificate and private key from DefaultAdmin.pfx certificate.

• Create a new domain user account and add the user to the Domain Admin group.

• The new account has full access to the domain:

From initial domain access and misconfiguration on AD CS, an attacker can escalate privilege and compromise the domain.

Privilege Escalation Attack Vectors

Privilege escalation can be achieved through various methods, exploiting different vulnerabilities or weaknesses in systems, software, or human behaviour. Here are some common methods used by attackers to escalate privileges:

• Exploiting Software Vulnerabilities: Attackers target known vulnerabilities in operating systems, applications, or services to gain elevated privileges. By exploiting vulnerabilities such as buffer overflows, code injection, or insecure configurations, attackers can execute arbitrary code with higher privileges than they are supposed to have.
• Misconfigurations: Misconfigured systems or applications may inadvertently grant excessive privileges to users or fail to enforce proper access controls. Attackers exploit misconfigurations in services, permissions, or settings to escalate their privileges within a system or network.
• Weak Access Controls: Weak or improperly configured access controls can allow attackers to bypass authentication mechanisms or gain unauthorised access to privileged accounts. This may involve exploiting weak passwords, default credentials, or insecure authentication protocols to escalate privileges.
• Social Engineering: Attackers may use social engineering techniques to trick users or administrators into granting them elevated privileges. This could include phishing attacks, pretexting, or other forms of manipulation to deceive users into disclosing credentials or executing malicious actions that result in privilege escalation.
• Malicious Scripts or Code Execution: Attackers may upload and execute malicious scripts or code on a system to exploit vulnerabilities and escalate privileges. This could involve uploading and executing shell scripts, PowerShell scripts, or other types of malwares to gain higher levels of access.
• Abusing Privileged Accounts: Attackers who have already compromised a privileged account may abuse their access to further escalate privileges. This could involve modifying user permissions, adding new accounts, or exploiting trust relationships between systems to gain additional privileges.
• Kernel Exploits: Kernel exploits target vulnerabilities in the underlying operating system kernel to gain escalated privileges. By exploiting vulnerabilities in the kernel, attackers can execute arbitrary code with kernel-level privileges, effectively gaining full control over the system.
• Privilege Escalation via Services: Attackers may exploit vulnerable services running on a system to escalate privileges. This could involve exploiting weaknesses in network services, such as web servers, databases, or remote access services, to gain higher access levels.

Preventing Privilege Escalation

Preventing privilege escalation is crucial for maintaining the security of systems and networks. Here are several strategies that organisations should employ to mitigate the risk of privilege escalation:

1. Protect and Scan Everything:

1. Conduct Regular Scans: Implement a robust vulnerability management program with regular scans of your system and IT infrastructure. Utilise advanced vulnerability scanning tools to identify potential weaknesses, including insecure applications, operating systems, and misconfigurations.
2. Strengthen Network Defences: Consider augmenting your defences with a Web Application Firewall (WAF) to detect and block malicious attacks at the network level, providing an additional layer of protection against privilege escalation attempts.

2. Privilege Accounts Management:

1. Enforce Accountability: Maintain a detailed inventory of all accounts within your organisation, including their permissions and access levels. Limit the number of privileged accounts and closely monitor their activities to prevent unauthorised access and privilege escalation.
2. Utilise Privilege Management Tools: Deploy privilege management tools to enforce strong authentication measures and restrict access to sensitive resources. Implementing multi-factor authentication (MFA) can further enhance account security and mitigate the risk of unauthorised access.

3. User and Entity Behaviour Analytics (UEBA):

1. Monitor Anomalies: Leverage User and Entity Behaviour Analytics (UEBA) tools to monitor user behaviour and detect anomalies indicative of potential threats or compromises. Establish user profiles and baseline activity to identify deviations and proactively respond to suspicious behaviour.
2. Enhance Threat Detection: By continuously analysing user activity, UEBA tools can provide valuable insights into potential privilege escalation attempts, allowing organisations to take pre-emptive action and mitigate risks effectively.

4. Enforce Strong Password Policies and Multi-Factor Authentication (MFA):

1. Promote Password Security: Implement stringent password policies and educate users on the importance of selecting strong, complex passwords. Conduct regular password audits to identify and address weak passwords and consider implementing enterprise password management tools to facilitate password security.
2. Enhance Authentication: Strengthen authentication mechanisms by implementing multi-factor authentication (MFA), requiring users to provide additional verification beyond passwords. MFA adds an extra layer of security, reducing the risk of unauthorised access and privilege escalation.

5. Database Security Measures:

1. Secure Sensitive Data: Protect databases and user input fields from potential exploits by implementing robust security measures, such as data encryption in transit and at rest. Regularly patch databases and sanitise user inputs to mitigate the risk of SQL injection attacks and unauthorised access.
2. Restrict File Permissions: Limit file permissions to minimise the number of users with write access, reducing the likelihood of unauthorised changes and potential privilege escalation incidents.

6. Employee Training and Awareness:

1. Foster a Culture of Security: Educate employees on cybersecurity best practices and raise awareness about the risks associated with privilege escalation attacks. Provide training on identifying phishing emails, suspicious links, and attachments, and empower employees to report potential threats promptly.

7. Develop Incident Response Plans: Establish and communicate response plans for handling cyberattacks, ensuring that employees are equipped to respond effectively during a security incident. Regularly review, test and update response plans to reflect evolving threats and vulnerabilities.

By adopting these preventive measures and incorporating them into their cybersecurity strategy, organisations can significantly reduce the risk of privilege escalation and enhance their overall security posture.

How Spartans Security Can Help

Spartans Security is dedicated to comprehensively understanding the unique needs of your organisation and stay up to date with emerging security threats. Our approach involves tailoring recommendations to provide the best-suited solutions for your specific requirements. We not only identify the most fitting security solutions but also offer practical advice on successful implementation. Our commitment lies in ensuring that your organisation not only achieves its security goals but does so with a seamlessly implemented and practical strategy for success.

Furthermore, seeking assistance from qualified IT security professionals like those at Spartans Security can be invaluable in implementing and maintaining effective strategies to mitigate the risk of privilege escalation. By leveraging resources such as the NIST Cybersecurity Framework to assess cyber security maturity, coupled with their expertise in vulnerability assessment, security awareness training, and security best practices can ensure that your organisation remains protected against evolving threats.

Conclusion

In conclusion, privilege escalation remains a significant threat in cybersecurity, posing serious risks to the integrity, confidentiality, and availability of organisational systems and data. Attackers continue to exploit vulnerabilities, misconfigurations, and human weaknesses to gain unauthorised access and elevate their privileges within networks and systems.

However, by adopting a proactive and multi-layered approach to security, organisations can effectively mitigate the risk of privilege escalation and strengthen their defences against potential attacks. Implementing principles such as least privilege, regular software updates, strong authentication, monitoring, and user education are essential to a robust security strategy.

Moreover, maintaining a culture of security awareness and fostering collaboration between IT teams, security professionals, and end-users is paramount to effectively identifying and responding to privilege escalation incidents.

By prioritising security measures, staying vigilant against emerging threats, and continuously refining security practices, organisations can better protect their assets and safeguard against the ever-evolving challenges posed by privilege escalation in today's digital landscape. Ultimately, the proactive implementation of preventive measures is key to minimising the impact of privilege escalation and preserving the trust and integrity of organisational systems and data.

Looking for cyber security advice and guidance? Then, feel free to reach out to us at info@spartanssec.com. Our dedicated experts look forward to providing robust solutions tailored to your organisation's needs.