Android Device Leaks Traffic When Connected to WiFi Network Even ‘Always-on VPN’ is Enabled

The installation of a VPN on your Android phone is supposed to ensure that all outgoing traffic is protected. This is what in the name of privacy the VPN providers claim at least.

It was discovered by Mullvad VPN during an ongoing security audit that every time an Android device connects to a WiFi network, it leaks traffic. While the most shocking thing is that this leak happens after enabling the following security features as well:-

  • Always-on VPN
  • Block connections without a VPN

Data leak

A connection check is sent outside the VPN tunnel by the Android operating system and outside VPN tunnels, the following types of data are being leaked:- 

  • Source IP addresses
  • DNS lookups
  • HTTPS traffic
  • NTP traffic

In Android’s documentation, the “VPN Lockdown” feature of Android appears to be described in an inaccurate manner, which means that Android users probably did not know this until now.

Therefore, Mullvad has issued a warning with the aim of bringing awareness to this issue. Furthermore, it also increases the pressure on Google as a result of such a measure.

Since this can present a privacy concern for some users depending on their threat model in some cases.

Privacy issue

VPNs mainly provide a protected network connection to the users that encrypts internet traffic over public networks in order to increase the privacy of users.

In order to provide a seamless experience, your VPN service will use the same IP address for all your Internet connections. As this will be used instead of your public IP address when connected to a VPN service.

With this program, users can bypass internet censorship and browse the web anonymously without any worry of being tracked.

In Android, you have the option of blocking network connections through Android’s “Network & Internet” setting, if you are not using a VPN to access the web.

With the help of this feature, the user’s IP address will not be accidentally leaked, if the VPN connection is interrupted or broken unexpectedly.

However, this feature is devalued by the requirements to acclimate special cases, such as the identification of captive portals, which undercut this feature.

In addition to the party controlling the connectivity check server, any entity that observes the traffic on the network will be able to observe and analyze the traffic on the connection check server.

As far as the leaks are concerned, there is nothing that can be done within the app to fix them. What experts can now do is inform users about the limitations of Android OS and remain transparent about the existence of these issues.

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Posted by Charlie