Pass-the-Hash Attacks

In the vast realm of cyber threats, “pass-the-hash” attacks are a particularly stealthy exploit that can leave organisations vulnerable to unauthorised access and data breaches. Pass-the-hash is a type of attack that takes advantage of how passwords are commonly stored—as cryptographic depictions known as hashes—to gain entry into secured systems without needing the actual password.

A pass-the-hash (PtH) attack occurs when an attacker captures account login credentials—specifically, hash values rather than plaintext passwords—from a device and uses the captured hash values to authenticate to other devices or services within a network. This technique bypasses standard authentication steps that normally require a user’s original password, allowing attackers seamless entry as though they were legitimate users.

To understand the nature of these cyber-attacks, let’s define a password hash. A password hash is like turning your standard password text into an indecipherable string of characters. Think of transforming “mypassword123” into something akin to “5f4dcc3b5aa765d61d832”.

When you enter your credentials on most secure platforms, this encrypted version (the hash) is verified against what’s stored in system security databases. And here lies the genius and vulnerability: hashing adds security by obscuring clear-text passwords during storage and transmission. But if someone obtains password hashes—they hold keys capable of unlocking doors across entire networks.

Pass-the-hash attacks unfold in stages, each meticulously crafted to evade detection and exploit system vulnerabilities. Initially, attackers need to gain access to a user’s hash values. Typically, attackers gain access through various means, such as phishing campaigns, malware infections, or exploiting existing network vulnerabilities.

Once the attacker has obtained these hashes—considered digital fingerprints of users’ passwords—they leverage this data against systems that utilise single sign-on (SSO) mechanisms or those with less stringent authentication processes. Unlike brute-force attacks, which aimlessly guess passwords until one fits, pass-the-hash strikes directly submit the captured hash instead of attempting password decryption.

The compromised system typically checks the submitted hash against its stored counterpart—if they match, entry is granted just as if a legitimate password was provided. At this point in the attack sequence, intruders can freely access sensitive areas in a network under the guise of trusted users.

Armed with access, cybercriminals might engage in lateral movements across networks, seeking higher privileged accounts for deeper infiltration. They might also perform data exfiltration without raising immediate alarms since all actions appear to be executed by recognised credentials from within the organisation.

Pass-the-hash attacks are emerging as a growing concern in the cybersecurity landscape. As attackers refine their techniques and adapt to changing work environments, these types of exploits are becoming more prevalent.

• An increase in remote work: The shift towards telecommuting has led many organisations to rely on single sign-on technology for seamless access across various services and applications. Remote work inadvertently provides fertile ground for pass-the-hash attacks, as one set of compromised credentials can open numerous doors in an organisation’s network.
• Prevalence of NTLM protocol: These attacks often target the NT LAN Manager (NTLM) protocol in Windows networks, a security feature still commonly used despite its vulnerabilities. Given that countless enterprises operate on Windows systems, this widespread adoption makes them prime targets for such exploits.
• Lateral movement and privilege escalation: By using captured hashes to authenticate elsewhere within the network, attackers can pivot from point to point (often undetected), gaining elevated privileges along the way. Such tactics may eventually compromise critical infrastructure like domain controllers with far-reaching consequences.
• Increased operational costs and revenue loss: Organisations hit by PtH attacks face not just data breaches but tangible financial repercussions, from disrupted operations leading to revenue loss to additional resources allocated for incident response efforts.
• Complexity of mitigation: Guarding against pass-the-hash requires tackling underlying issues, which might include comprehensive audits, patch management, and enhanced user training—all part of a larger battle against identity theft and malware incursion, thereby complicating defence strategies further than simpler threats would necessitate.
• Exploitation of single sign-on (SSO): Attackers exploit SSO mechanisms inherent in authentication protocols like LM or Kerberos used by Windows networks because once they acquire valid hash values, those credentials remain effective until passwords change, an eventuality that may not occur frequently enough.
• Broad impact: The extent of damage is directly proportionate to the privilege level associated with compromised accounts, with potential outcomes ranging from exfiltrated data up to full-blown system control.
• Difficulty in detection: PtH leverages legitimate authentication processes built into systems, so it insidiously camouflages itself among normal traffic. In turn, attackers evade standard detection measures, leaving organisations vulnerable until it’s too late.

Given these factors, it’s clear why PtH attacks are a growing concern. They exploit fundamental aspects of widely used authentication protocols, which can lead to significant financial and operational impacts that are challenging to mitigate and detect.

To stave off pass-the-hash attacks, organisations must adopt a multi-layered approach to cybersecurity. Here are several effective strategies that can help prevent these types of intrusions:

1. Use advanced password policies: Implementing complex password requirements and encouraging frequent changes can limit the usefulness of captured hashes. Moreover, deploying multi-factor authentication (MFA) adds an additional layer of security beyond just passwords. Consider using a password generator to help you create strong and secure passwords.
2. Restrict and monitor use of privileged accounts: Minimise the number of users with high-level privileges and closely monitor their activity. Ensure that administrative accounts are used only when necessary, employing standard user accounts for everyday operations. These measures underscore the importance of a privileged access management system.
3. Employ least privilege principle: Each user should have the minimum level of access required to perform their job functions and nothing more. These zero-trust security measures limit potential damage if credentials are compromised since attackers would gain less initial network access.
4. Implement endpoint security measures: Equip devices with up-to-date antivirus software and intrusion detection systems that could alert you to suspicious activities indicative of hash capturing or other attacks in progress.
5. Network segmentation: Divide your network into smaller segments to contain any breaches within isolated zones, thereby limiting lateral movement possibilities for attackers who manage to infiltrate one segment.
6. Patch management: Regularly update all systems with the latest patches from vendors, often including fixes for vulnerabilities that PtH attacks could exploit.
7. Disable outdated authentication protocols: Where feasible, retire older and less secure authentication protocols such as NTLM in favour of more secure alternatives like Kerberos. Additionally, consider disabling the storage of LM hash values on Windows systems altogether since newer versions don’t require them, and they present an unnecessary risk.
8. Leverage Windows Credential Guard: Organisations using modern Windows environments should take advantage of Credential Guard, which uses virtualisation-based security to protect credential derivatives like hashes. This makes it significantly harder for attackers to extract and use them in pass-the-hash attacks.
9. Educate employees about social engineering: Since social engineering tactics often serve as a starting point for PtH attacks through methods like phishing, staff members must be trained to recognise these threats. Awareness can drastically reduce the likelihood of sensitive information being divulged or compromised by deceitful means.

By implementing these preventative strategies with dedication and continuous refinement, an organisation can bolster its defences against complex cyber threats like pass-the-hash attacks. Establishing robust password policies, minimising privilege sprawl, and securing endpoints against intrusion attempts while educating employees about social engineering—are all cornerstones in building a resilient cybersecurity posture that safeguards operational integrity and digital assets amidst an ever-evolving threat landscape.

Proofpoint helps prevent pass-the-hash attacks through its comprehensive suite of tools and solutions designed to detect, prevent, and respond to these threats.

Proofpoint’s Identity Threat Detection & Response platform features two primary components to help continuously protect organisations from PtH attacks. These components include:

• Proofpoint Shadow: This tool can help stop attackers before they cause damage by detecting and responding to potential PtH attacks.
• Targeted Attack Protection (TAP): Proofpoint’s TAP is an innovative solution that detects malicious behaviour, such as credential theft, a common technique in PtH attacks. TAP uses machine learning algorithms and threat intelligence to identify suspicious activities, providing robust protection against PtH attacks.

In addition to these tools, Proofpoint’s Email Protection Solutions provide robust protection against phishing attempts, which attackers can use to harvest credentials for PtH attacks. By leveraging advanced technology and cybersecurity expertise, Proofpoint helps organisations safeguard their networks from malicious actors attempting lateral movement, including PtH attacks.

Furthermore, Proofpoint’s URL Defense feature protects users from malicious links, which attackers can use in phishing attempts to harvest credentials for PtH attacks. This feature uses a two-step approach to ensure maximum protection against credential harvesting and other types of malicious activity.

Overall, Proofpoint offers a range of solutions and features that address the various techniques and strategies used in PtH attacks, providing organisations with a comprehensive defence against these threats. To learn more about how to protect your organisation from such attacks, contact Proofpoint.