A vulnerability broker published a video demonstrating one of several flaws it has found in the privacy-focused Tails operating system, which is used by those seeking to make their Web browser harder to trace.
Exodus Intelligence of Austin, Texas, said its short clip shows how the real IP address of a Tails user can be revealed using the flaw. The company said it hoped publicizing its findings would serve as a warning to users about putting "unconditional trust" in a software platform.
"Users should question the tools they use, they should go even further to understand the underlying mechanisms that interlock to grant them security," Exodus said in a blog post on Wednesday.
Tails is a self-contained, Linux-based operating system and suite of applications that can be carried on a USB stick, an SD card or a DVD. It is designed in part for use on public Internet terminals, protecting a person's online activity and leaving few digital traces on the computer it runs on.
Exodus, which sells software vulnerabilities to vetted parties, came under fire earlier this week for how it approached disclosing the problem in Tails, which has been endorsed by former NSA contractor Edward Snowden.
The company tweeted on Monday that it had found several zero-day vulnerabilities in Tails without notifying developers of the project first. Critics worried that Exodus might sell the information, potentially putting users at risk.
CEO Aaron Portnoy later said the company would not sell the information and would provide it to Tails so the issues could be fixed. It wasn't clear if public pressure contributed to that decision, but the Tails project said it appreciated the disclosure.
The flaw Exodus described in its blog post is contained in an open-source networking component within Tails called I2P, which encrypts Web traffic and masks a computer's true IP address. Exodus said the vulnerability is present on default, fully patched versions of Tails and allows a malicious payload to be delivered to the victim's computer.
Obtaining a computer's true IP address does not necessarily identify a specific user. But it does indicate what service provider supplies Internet connectivity to the machine, which could then be forced by court order to disclose the subscriber.
Developers from Tails wrote on Tuesday that there are many programs in its software package, all of which periodically have security vulnerabilities. It encourages security researchers to audit and report flaws.
"Some people report such vulnerabilities, and then they get fixed: This is the power of free and open source software," the project wrote. "Others don't disclose them, but run lucrative businesses by weaponizing and selling them instead. This is not new and comes as no surprise."
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