VPN bug poses privacy threat to BitTorrent downloaders

The bug could be used to unmask a computer's real IP address

A bug affecting some VPN services can be used to figure out a computer's real IP addresses, including those of BitTorrent users, which could pose a huge privacy and possibly a legal risk.

The vulnerability affects those services that allow port forwarding, according to VPN provider Perfect Privacy, which wrote about the issue on Thursday.

A successful attack requires a couple of conditions to be met: the attacker must be on the same VPN network as the victim, who also has to be lured into connecting to a resource controlled by the attacker.

By tricking a victim into opening an image file, for example, an attacker who has port forwarding enabled on their account can see the request from the victim's real IP addresses.

"The crucial issue here is that a VPN user connecting to his own VPN server will use his default route with his real IP address, as this is required for the VPN connection to work," Perfect Privacy wrote.

For the IP address leak attack to work, the attacker must know the victim's VPN exit IP address, which Perfect Privacy suggested could be discovered by luring a victim to a website under their control.

Perfect Privacy tested nine VPN providers before it went public with the flaw. Five were vulnerable, and those providers have been notified, it said.

But the company warned "other VPN providers may be vulnerable to this attack as we could not possibly test all."

The vulnerability could be used to unmask people who are using BitTorrent clients to download content, wrote Darren Martyn, a security enthusiast and penetration tester, on his blog.

The BitTorrent protocol is used by client programs such as uTorrent to download content distributed among many users across the Internet. The entertainment industry has waged legal battles aimed at stopping the sharing of copyrighted content on file-sharing services.

To make it harder for their computer's real IP address to be identified, those downloading content often use VPNs. In theory, it makes their computers harder to link back to an ISP, depending on how a VPN provider responds to legal requests.

Martyn outlined how the entertainment industry could use the flaw to identify computers downloading protected content in a section described on his blog as "How to be evil."

"I believe this kind of attack is probably going to be used heavily by copyright-litigation firms trying to prosecute torrent users in the future, so it's probably best to double check that the VPN provider you are using does not suffer this vulnerability," he wrote.

Join the newsletter!

Error: Please check your email address.
Rocket to Success - Your 10 Tips for Smarter ERP System Selection
Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

Jeremy Kirk

IDG News Service
Show Comments

Cool Tech

Breitling Superocean Heritage Chronographe 44

Learn more >

SanDisk MicroSDXC™ for Nintendo® Switch™

Learn more >

Toys for Boys

Family Friendly

Panasonic 4K UHD Blu-Ray Player and Full HD Recorder with Netflix - UBT1GL-K

Learn more >

Stocking Stuffer

Razer DeathAdder Expert Ergonomic Gaming Mouse

Learn more >

Christmas Gift Guide

Click for more ›

Most Popular Reviews

Latest Articles

Resources

PCW Evaluation Team

Edwina Hargreaves

WD My Cloud Home

I would recommend this device for families and small businesses who want one safe place to store all their important digital content and a way to easily share it with friends, family, business partners, or customers.

Walid Mikhael

Brother QL-820NWB Professional Label Printer

It’s easy to set up, it’s compact and quiet when printing and to top if off, the print quality is excellent. This is hands down the best printer I’ve used for printing labels.

Ben Ramsden

Sharp PN-40TC1 Huddle Board

Brainstorming, innovation, problem solving, and negotiation have all become much more productive and valuable if people can easily collaborate in real time with minimal friction.

Sarah Ieroianni

Brother QL-820NWB Professional Label Printer

The print quality also does not disappoint, it’s clear, bold, doesn’t smudge and the text is perfectly sized.

Ratchada Dunn

Sharp PN-40TC1 Huddle Board

The Huddle Board’s built in program; Sharp Touch Viewing software allows us to easily manipulate and edit our documents (jpegs and PDFs) all at the same time on the dashboard.

George Khoury

Sharp PN-40TC1 Huddle Board

The biggest perks for me would be that it comes with easy to use and comprehensive programs that make the collaboration process a whole lot more intuitive and organic

Featured Content

Product Launch Showcase

Latest Jobs

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?