Split tunneling allows organizations to divide internet connections into two separate streams. This method will route organization specific data through a VPN tunnel, but routes other traffic through the remote user’s default gateway.

While split tunneling offers benefits in terms of flexibility and bandwidth efficiency, it also introduces significant security risks.

How Split Tunneling Works

Typically, when a user connects to a VPN, all of their internet traffic is routed through the VPN tunnel. This ensures that the traffic is encrypted and protected from potential eavesdropping and cyberattacks. However, with split tunneling, the user can configure the VPN to selectively route only specific traffic through the secure tunnel, while the rest of the traffic goes directly to the internet, unencrypted.

For example, a user may want to route traffic to a corporate network through the VPN for access to sensitive files, while allowing less sensitive web browsing or streaming services to bypass the VPN and go through the regular internet connection. This selective routing is typically managed by the user’s device or the VPN client software, which decides which traffic should go through the secure tunnel and which can be routed directly to the internet.

Types of Split Tunneling

  1. Destination-based Split Tunneling
    In destination-based split tunneling, traffic is routed to the VPN tunnel based on the destination IP address or domain. For instance, traffic destined for specific websites, like a corporate intranet or a private server, will go through the VPN, while all other traffic, such as public websites or video streaming services, bypass the VPN and access the internet directly.
  2. Application-based Split Tunneling
    This method allows certain applications to route their traffic through the VPN tunnel, while others are allowed to use the direct, unencrypted connection. For example, an organization might require that its financial software uses the VPN, while web browsers and email clients do not.
  3. Route-based Split Tunneling
    Route-based split tunneling allows for more granular control by routing traffic based on specific network routes. The VPN client or firewall can be configured to determine which traffic should follow which path based on predefined routing rules.

Benefits of Split Tunneling

  1. Bandwidth Efficiency
    By allowing non-sensitive traffic to bypass the VPN tunnel, the overall load on the VPN server is reduced, leading to better performance for critical applications that require the secure tunnel. This is especially important in organizations where VPN connections may become slow or congested when all traffic is routed through the tunnel.
  2. Enhanced Speed and Performance
    Without routing all internet traffic through the VPN, users can experience faster browsing, streaming, and gaming performance. Since VPN encryption can sometimes slow down internet speed, bypassing the VPN for less sensitive traffic ensures a more efficient use of network resources.
  3. Reduced Latency
    For applications or services that do not require the added layer of security provided by a VPN, such as video streaming, online gaming, or general web browsing, split tunneling can help reduce latency. Direct access to the internet allows users to connect faster to the services they need without the added delay of encrypted VPN traffic.
  4. Flexibility
    Split tunneling gives users greater flexibility to manage their internet traffic. It allows organizations and individuals to control which data is sent securely through the VPN and which data can be handled without encryption. This flexibility can be helpful in scenarios where certain services or applications do not require the security of a VPN.

Risks and Drawbacks of Split Tunneling

Despite its advantages, split tunneling introduces several security risks that must be carefully managed:

  1. Security Vulnerabilities
    By allowing certain traffic to bypass the VPN, split tunneling can expose sensitive data to the open internet. Any unencrypted traffic is susceptible to interception, which could allow attackers to eavesdrop on data, steal credentials, or exploit vulnerabilities. For example, sensitive information such as passwords, corporate files, or private communications could be compromised when sent over an unsecured network.
  2. Malware and Phishing Risks
    When users bypass the VPN to access public websites or services, they may expose themselves to malware and phishing attacks. These attacks could occur outside the secure VPN tunnel, making it harder to detect and mitigate the threat. Without the protective layer of the VPN, users may inadvertently download malicious software or be tricked into revealing personal information.
  3. Inconsistent Security Policies
    With split tunneling, it becomes difficult to enforce consistent security policies across an organization. If only certain traffic is routed through the VPN, unauthorized applications or websites could bypass corporate security protocols, leading to gaps in the organization’s overall defense.
  4. Data Leakage
    Data leakage can occur if sensitive information is inadvertently transmitted over an unprotected network. This could be particularly problematic for industries with strict regulatory requirements (e.g., healthcare, finance, or government), where leakage of sensitive data could lead to compliance violations, financial penalties, or reputational damage.

Best Practices for Using Split Tunneling Safely

If an organization or individual chooses to implement split tunneling, they must do so with caution and follow best practices to mitigate the associated risks:

  1. Use Split Tunneling for Non-Sensitive Traffic Only
    It is important to ensure that only non-sensitive or low-risk traffic bypasses the VPN. Any traffic that involves sensitive data or internal resources should always pass through the secure tunnel to avoid exposure to potential threats.
  2. Enforce Strict Endpoint Security
    Users who utilize split tunneling should have strong endpoint security measures, such as up-to-date antivirus software, firewalls, and intrusion detection systems, to reduce the likelihood of malware or attacks affecting the unencrypted traffic.
  3. Monitor and Audit Traffic
    Constantly monitor and audit traffic to ensure that split tunneling is not inadvertently exposing sensitive data or violating security policies. This may involve analyzing traffic logs and conducting vulnerability assessments.
  4. Implement Contextual Access Control
    For organizations, contextual access control can be implemented to restrict which users, devices, and applications are allowed to use split tunneling. By limiting split tunneling to trusted and authorized users, the risk of exposure is reduced.

Conclusion

Split tunneling is a useful feature for improving network performance, bandwidth efficiency, and flexibility, especially for users and organizations that need to prioritize certain types of traffic. However, it also introduces security risks by bypassing encryption for some internet traffic, leaving it vulnerable to potential attacks.

To mitigate these risks, organizations should use split tunneling selectively, monitor traffic carefully, and ensure that strong endpoint security measures are in place. By balancing convenience with security, split tunneling can be a powerful tool when used correctly.

About BlackFog

BlackFog is the leader in on-device data privacy, data security and ransomware prevention. Our behavioral analysis and anti data exfiltration (ADX) technology stops hackers before they even get started. Our cyberthreat prevention software prevents ransomware, spyware, malware, phishing, unauthorized data collection and profiling and mitigates the risks associated with data breaches and insider threats. BlackFog blocks threats across mobile and desktop endpoints, protecting organizations data and privacy, and strengthening regulatory compliance.