Patrick Wardle is known for being a Mac malware specialist — but his work has traveled farther than he realized.

A former employee of the NSA and NASA, he is also the founder of the Objective-See Foundation: a nonprofit that creates open-source security tools for macOS. The latter role means that a lot of Wardle’s software code is now freely available to download and decompile — and some of this code has apparently caught the eye of technology companies that are using it without his permission.

Wardle will lay out his case in a presentation on Thursday at the Black Hat cybersecurity conference with Tom McGuire, a cybersecurity researcher at Johns Hopkins University. The researchers found that code written by Wardle and released as open source has made its way into a number of commercial products over the years — all without the users crediting him or licensing and paying for the work.

The problem, Wardle says, is that it’s difficult to prove that the code was stolen rather than implemented in a similar way by coincidence. Fortunately, because of Wardle’s skill in reverse-engineering software, he was able to make more progress than most.

“I was only able to figure [the code theft] out because I both write tools and reverse engineer software, which is not super common,” Wardle told The Verge in a call before the talk. “Because I straddle both of these disciplines I could find it happening to my tools, but other indie developers might not be able to, which is the concern.”

The thefts are a reminder of the precarious status of open-source code, which undergirds enormous portions of the internet. Open-source developers typically make their work available under specific licensing conditions — but since the code is often already public, there are few protections against unscrupulous developers who decide to take advantage. In one recent example, the Donald Trump-backed Truth Social app allegedly lifted significant portions of code from the open-source Mastodon project, resulting in a formal complaint from Mastodon’s founder.

One of the central examples in Wardle’s case is a software tool called OverSight, which Wardle released in 2016. Oversight was developed as a way to monitor whether any macOS applications were surreptitiously accessing the microphone or webcam, with much success: it was effective not only as a way to find Mac malware that was surveilling users but also to uncover the fact that a legitimate application like Shazam was always listening in the background.

Wardle — whose cousin Josh Wardle created the popular Wordle game — says he built OverSight because there wasn’t a simple way for a Mac user to confirm which applications were activating the recording hardware at a given time, especially if the applications were designed to run in secret. To solve this challenge, his software used a combination of analysis techniques that turned out to be unusual and, thus, unique.

But years after Oversight was released, he was surprised to find a number of commercial applications incorporating similar application logic in their own products — even down to replicating the same bugs that Wardle’s code had.

Image: Patrick Wardle

Three different companies were found to be incorporating techniques lifted from Wardle’s work in their own commercially sold software. None of the offending companies are named in the Black Hat talk, as Wardle says that he believes the code theft was likely the work of an individual employee, rather than a top-down strategy.

The companies also reacted positively when confronted about it, Wardle says: all three vendors he approached reportedly acknowledged that his code had been used in their products without authorization, and all eventually paid him directly or donated money to the Objective-See Foundation.

Code theft is an unfortunate reality, but by bringing attention to it, Wardle hopes to help both developers and companies protect their interests. For software developers, he advises that anyone writing code (whether open or closed source) should assume it will be stolen and learn how to apply techniques that can help uncover instances where this has happened.

For corporations, he suggests that they better educate employees on the legal frameworks surrounding reverse engineering another product for commercial gain. And ultimately, he hopes they’ll just stop stealing.