The Mac and iOS software developer Panic has had the source code for several of its apps stolen.
Panic founder Steven Frank admitted in a blog post that it happened after he downloaded an infected copy of the video encoding tool Handbrake.
He said there was no sign that any customer data was accessed and that Panic’s web server was not affected.
Users have been warned to download Panic’s apps only from its website or the Apple App Store.
Panic is the creator of web editing and file transfer apps Coda and Transmit, and the video game Firewatch.
On 2 May Handbrake was hacked, with the Mac version of the app on one of the site’s download servers replaced by a malicious copy.
The infected app was discovered and removed on 6 May.
In what Mr Frank called “a case of extraordinarily bad luck”, he downloaded the malicious version of Handbrake and launched it “without stopping to wonder why Handbrake would need admin privileges… when it hadn’t before”.
“And that was that, my Mac was completely, entirely compromised in three seconds or less.”