Pass-the-hash attack

What is a pass-the-hash attack?

Pass-the-hash is a technique that allows adversaries to take control of an access management routine by stealing hashed credentials and leveraging them to mimic the original user. A password hash is a non-descript, irreversible form of a password stored securely on a server or endpoint. During every subsequent login, this hash is verified to authenticate the user, thereby eliminating the need for providing a password every time. This means that during a pass-the-hash attack, attackers don't even need to crack the hash; all they need to do is feed—or pass—the hash to impersonate a legitimate user and trick the authentication system.

Authentication protocols typically require a user name and a password. However, when a pass-the-hash attack is attempted, attackers try to force the stolen hash and gain access to critical endpoints. This allows them to bypass the alerts raised during failed login attempts while using passwords and does not notify the user about the privileges being misused.

Why is it important to mitigate a pass-the-hash attack?

Pass-the-hash is often a silent process with a profound impact on an enterprise's security, making it a growing concern. By the time anomalies are detected, the attacker may have already infiltrated confidential business information. The absence of MFA adds to this risk, allowing the hacker to escape stringent security checks and sneak into a business environment.

A successful pass-the-hash attempt can let attackers impersonate legitimate users and misuse their privileges. Unmonitored user access privileges make it effortless for hackers to get a foothold on critical business operations. All that is required is one hash, which becomes a master key for the hacker to maneuver across any network.

Mitigating a pass-the-hash attack works beyond just restricting unauthorized users from navigating with elevated privileges and adopts advanced strategies and integrations to allow organizations to significantly improve their security posture.

How does a pass-the-hash attack work?

A pass-the-hash attack begins when an attacker gains access to local account privileges. Here's an example of a common pass-the-hash attempt:

• A user with malicious intent attempts to steal password hashes from a sensitive endpoint. This is done by performing phishing attacks, injecting malware, or making use of dumping tools like Mimikitz.
• The obtained hash allows the attacker to log in to target endpoints, and with the absence of MFA, the process is made simpler.
• The attacker then masquerades into the compromised endpoint and scouts for the privileges associated with the account.
• The privileges of this account are used to seamlessly access and switch between multiple other systems.
• The privileges are used to perform privilege misuse operations, like data modification, stealing information, or permanent change to login information of user accounts.

 

Who is vulnerable to pass-the-hash attacks?

Organizations and systems that rely on New Technology LAN Manager (NTLM) to manage user credentials in the forms of hashes should beware of this attack. While NTLM simplifies authentication and allows for subsequent logins without passwords, the use of hashes makes it highly vulnerable to the pass-the-hash technique. The vulnerability is most prevalent in Windows environments, and with most organizations solely relying on SSO for user authentication, it has become increasingly difficult for them to mitigate such attacks.

How is a pass-the-hash attack detected?

Since pass-the-hash attacks impersonate legitimate user behavior, it can take a while to detect anomalies that arise. Additionally, any attacker can use these privileges to surpass security measures, like account lockouts, password resets, and other account management features.

However pass-the-hash attacks are not entirely undetectable. An effective detection method is to leverage log correlation to monitor user behavior over privileged resources and take necessary measures when suspicious actions arise. Another approach is to always expect pass-the-hash attacks and prevent breeding grounds for them, pushing your organization towards continuous security improvements.

Detecting pass-the-hash attacks is a multi-step process that monitors user activities like:

• Login attempts during unusual hours.
• Login attempts from unusual IP ranges and endpoints.
• A surge in the number of failed login attempts.
• A successful login followed by periodic and unusual actions on certain accounts.
• A surge in the number of bulk actions performed (e.g., file downloads, password resets, subsequent logins to multiple accounts, etc.).

How to protect against pass-the-hash attacks

Pass-the-hash attacks can befall an organization's security infrastructure if it's not monitored properly. Deploying an effective privilege access management strategy allows for granular control of privileged resources and condenses the attack surface for privilege misuse.

Stay resilient against pass-the-hash attacks by ensuring the following controls are in place:

• Extensively adopt MFA into your access management routines to add a layer of security to your SSO authentication.
• Enforce the principle of least privilege while granting access to sensitive endpoints.
• Eliminate access provisioning on an all-or-nothing basis and enforce just-in-time access controls based on demand.
• Identify accounts at risk with periodic auditing to manage provisioning and deprovisioning of access.
• Integrate with SIEM and extended detection and response (XDR) tools to keep a close watch on the user activities over privileged resources and stay informed about the anomalies that arise.

Protect your hashed user credentials with PAM360

Considering the cascading effects that a pass-the-hash attack can bring on enterprise security, it is important to adopt a strategy that not only manages your enterprise passwords but also governs the actions revolving around them. ManageEngine PAM360 is a unified privilege access management solution for enterprises that addresses the complex challenges associated with controlling and safeguarding critical IT resources across all verticals of your business.

With comprehensive features like role-based access controls and just-in-time privilege elevation, PAM360 offers fine-grained access to privileged resources and sets the base for sound operational efficiency. Every user activity is constantly monitored and logged as audits to study user behavior patterns and identify accounts at risk.

Additionally, PAM360's Zero Trust controls ensures zero standing privileges within your privilege access routines, while the integration with SIEM and endpoint management tools provides comprehensive analysis of what is happening with your PAM environment to help you condense the attack surface and stay on top of threats that emerge.