What is a VPN Connection Hijack in Phishing?

Definition:

A VPN connection hijack in phishing involves exploiting vulnerabilities to take over an existing VPN session or bypass authentication protocols, granting unauthorized access to secure networks.

Why It Matters

In the realm of phishing and social engineering, VPN connection hijacks constitute a substantial threat. Attackers exploit these tactics to infiltrate otherwise secure networks by masquerading as trusted endpoints. VPNs serve as essential tools for organizations, ensuring a secure communication tunnel over potentially exposed internet pathways. By hijacking these connections, an attacker can assume the identity of a legitimate user, effectively bypassing numerous security measures and gaining the ability to conduct more in-depth attacks, such as data exfiltration or additional credential theft.

This technique primarily surfaces in scenarios where attackers can intercept or predict authentication tokens or leverage vulnerabilities like unpatched software or zero-days. By circumventing the expected authentication flow, attackers make a seamless entry into critical IT infrastructure, often eluding detection by blending in with legitimate network traffic. The attack potential is significant, particularly given the increase in remote work arrangements and the reliance on VPNs for secure telecommuting.

In Practice

Consider a phishing campaign targeting an organization using a prevalent VPN vendor known to have a vulnerability documented in the CISA Known Exploited Vulnerabilities Catalog. Attackers might craft a lure email appearing to be an alert from the organization’s IT department, mimicking internal communication style:

Subject: Immediate Action Required: VPN Upgrade 

From: support@trusted-network.com

Dear User,

We are performing urgent updates to our VPN system to enhance security measures. You are required to authenticate your current session to comply with the new security protocols. Please log in using the following link to prevent disruption: 

https://secureportal-network.com/login/authenticate

Thank you for your prompt attention to this matter.

IT Security Team

The link directs users to a sophisticated phishing site replicating the actual VPN portal. Unwary users who enter their credentials provide attackers with information required to hijack their sessions. The attackers then use this information to bypass VPN protections and enter the network seamlessly.

Another practical example involves leveraging a zero-day vulnerability that allows for the prediction of session tokens. Attackers who have already acquired partial network credentials through previous phishing efforts launch a script to guess these tokens, gaining access without raising suspicion. This requires less social engineering but has a similar tactical effect: infiltrating secure communications under the guise of trusted users.

A historical tactic includes utilizing malware that, once deployed via a phishing payload, adjusts DNS settings or installs rootkits to divert legitimate VPN traffic through attacker-controlled servers. This approach not only facilitates easier collection of user credentials but can also insert the attacker directly into active VPN sessions.

Related Terms

Practitioners interested in VPN connection hijacks should also familiarize themselves with session hijacking, which involves intercepting and taking control of user sessions in different contexts. Additionally, understanding zero-day exploits — vulnerabilities unknown to those needing to fix them — provides insight into how many hijacks are initially executed. Lastly, knowledge of social engineering is crucial, as these techniques often lay the groundwork for an effective hijack.