Understanding iCloud Private Relay and Its Potential Leaks

If you subscribe to iCloud+ and use Safari, you might have activated iCloud Private Relay for added privacy. This feature aims to hide your actual IP address and location from websites. However, security researchers have identified ways certain WebKit features bypass this protection.

Recent Findings on iCloud Private Relay

Researchers Talal Haj Bakry and Tommy Mysk discovered vulnerabilities within WebKit that sidestep Private Relay’s privacy shield. They found that DNS prefetching, a WebAuthn feature related to passkeys, and WebTransport can bypass WebKit’s proxy. This means they could expose your real IP address or DNS server information, compromising your privacy.

Mechanisms Behind the Leak

DNS Prefetching: Normally, browsers use DNS prefetching to speed up browsing by resolving addresses of links. However, WebKit sends these requests through your regular DNS, potentially exposing your real network details.

Passkey Verification: The WebAuthn feature might leak your IP when verifying if certain websites belong together, as it happens outside Safari’s proxied path.

WebTransport Connection: This feature allows faster connections by establishing a direct WebTransport channel. Unfortunately, it might reveal your real IP, bypassing the Private Relay.

Who Could Be Affected?

Anyone using Safari with iCloud Private Relay might be impacted by these leaks. Browsers or apps built on WebKit could also be vulnerable. However, VPNs do not face these specific leaks due to their system-level traffic tunneling.

Maintaining Privacy with Safeguards

• Keep Private Relay on: Continue using it to protect most Safari browsing activities. Turn it on via Settings > your name > iCloud > Private Relay.
• Regular Updates: Keep your devices updated with the latest iOS, iPadOS, and macOS releases to receive timely security patches.
• Consider Using a VPN: For better IP protection, use a reputable VPN, complementing the privacy offered by Private Relay.
• Monitor Browser Privacy Updates: Some browsers already address these leaks by altering their handling of vulnerable features.

Current findings emphasize the importance of knowing what privacy features protect. While iCloud Private Relay offers strong protection, it is not foolproof against some browser-level bypasses. Users should stay informed on updates and use additional safeguards like VPNs when necessary.