VPN and local adapters.

[Ric555]

Hi.

I would like to know if an attacker on a local network can intercept my data, even after connecting to a VPN. Here is an imaginary scenario, with an HTTP connection:

local IP (192.168.1.2) > VPN server (75.x.x.x)

local adapter (10.0.0.2) > internet (161.x.x.x)

When using Wireshark to monitor the traffic from the local adapter, it was possible to view all of its content. Can the attacker, who is on the same local network (a public Wi-Fi), see all the traffic on the local adapter?

I described this scenario because this is how I observed Kaspersky VPN works. I don't know if this is specific to this VPN or if this is how VPNs generally work.

[Berny]

Hi @Ric555

2 hours ago, Ric555 said:

after connecting to a VPN

When activating a VPN connection you are  using a ‘private tunnel’ through which you encrypt all data
transmitted over the network which is preventing cybercriminals to intercept or view your data.

[KarDip]

17 hours ago, Ric555 said:

Hi.

I would like to know if an attacker on a local network can intercept my data, even after connecting to a VPN. Here is an imaginary scenario, with an HTTP connection:

local IP (192.168.1.2) > VPN server (75.x.x.x)

local adapter (10.0.0.2) > internet (161.x.x.x)

When using Wireshark to monitor the traffic from the local adapter, it was possible to view all of its content. Can the attacker, who is on the same local network (a public Wi-Fi), see all the traffic on the local adapter?

I described this scenario because this is how I observed Kaspersky VPN works. I don't know if this is specific to this VPN or if this is how VPNs generally work.

In the scenario you've described, the use of a VPN should generally secure your data against interception by an attacker on the same local network, even if they use tools like Wireshark. Here's a breakdown of what happens and why the data may or may not be visible:

How VPNs Protect Your Traffic

1. Encryption: A VPN encrypts all traffic from your device to the VPN server. This encryption ensures that even if an attacker intercepts the data packets on the local network, they cannot read the contents without the encryption key.

2. Encapsulation: The VPN encapsulates your data within a secure tunnel, adding a layer of protection. Any traffic captured on the local adapter or the public Wi-Fi should appear as encrypted VPN packets (e.g., OpenVPN, WireGuard, or IKEv2 packets) rather than readable HTTP data.

Your Scenario with Wireshark

If you are using Wireshark on the local adapter (10.0.0.2), you will see traffic that your device sends and receives. If the VPN is properly configured and active, this traffic will be encrypted. Here’s why:

• Before the VPN: Traffic is encrypted before it leaves your device.
• After the VPN: The encrypted traffic is sent to the VPN server, where it is decrypted and forwarded to the intended destination.

If you observed readable HTTP data (unencrypted content) while monitoring the local adapter with Wireshark, this could indicate:

1. Traffic Leak: Certain traffic (e.g., DNS queries, software updates, or split-tunneled applications) might bypass the VPN if split tunneling is enabled. This traffic would be visible in plaintext.
2. Improper VPN Configuration: If the VPN is not set up correctly, some or all of the traffic may not be routed through the VPN tunnel.
3. Local HTTP Traffic: If you're connecting to resources within the same local network, the VPN might not encrypt this traffic because it's not routed through the internet.

Can an Attacker See the Traffic?

• Encrypted Traffic: If the VPN is properly encrypting your traffic, an attacker on the same network will only see encrypted VPN packets, which are useless without the encryption key.
• Unencrypted Traffic: If certain traffic bypasses the VPN (e.g., due to split tunneling or a misconfiguration), the attacker can intercept and potentially read this unencrypted traffic.

Specific to Kaspersky VPN or All VPNs?

This behavior is not specific to Kaspersky VPN. All VPNs operate in a similar manner:

• If properly configured, your traffic should be encrypted and safe from attackers on the local network.
• However, misconfigurations, leaks, or specific VPN settings (like split tunneling) can expose unencrypted data.

Recommendations

1. Verify VPN Traffic Routing:

   • Use tools like Wireshark to ensure that all traffic is routed through the VPN tunnel and appears encrypted.
   • Check for DNS leaks using online tools or by monitoring DNS queries in Wireshark.

2. Disable Split Tunneling (if not needed): Split tunneling allows some traffic to bypass the VPN, which can expose unencrypted data to local attackers.

3. Use HTTPS: Always use HTTPS websites to ensure end-to-end encryption, even if your VPN fails.

4. Check VPN Settings: Ensure that your VPN is configured to route all traffic through the secure tunnel (e.g., enable "kill switch" and "force all traffic through VPN").

If Kaspersky VPN seems to allow leaks, consider reporting the issue to their support team or testing with another VPN service to compare results.

Edited November 29 by KarDip
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