Crooks push Mac malware through fake OpenAI Codex ads

Cybercrims are using fake OpenAI Codex download pages to trick Mac developers into running malware disguised as installation commands.

Researchers at Cato Networks uncovered the campaign after spotting sponsored Google search results targeting people looking to download Codex for macOS.

The ads direct would-be users to a convincing-looking download page hosted on Google Sites, complete with the familiar OpenAI branding.

There is, however, no Codex waiting at the other end.

Instead of serving up an installer, the fake site tells Mac users to open Terminal, paste in a supplied command, and run it.

The instructions are dressed up as part of the installation process, but the command quietly kicks off a multi-stage malware infection.

It's a variation of the increasingly popular "ClickFix" technique, in which attackers convince victims to execute malicious commands themselves rather than relying on a dodgy attachment or executable to do the dirty work.

In this case, the command begins with what appears to be a legitimate npm instruction for installing Codex.

Tacked onto it, however, is code that decodes a Base64-encoded URL, fetches an attacker-controlled shell script and pipes it into zsh.

That script pulls down another stage, which contacts the attacker's server to report that someone has taken the bait before downloading a Mach-O executable to “/tmp/helper.” It then removes security information macOS uses to flag suspicious downloads, helping the malware dodge the usual warnings before it launches.

Cato said the final binaries are universal Mach-O files, meaning they can run natively on both Intel-powered Macs and newer Apple Silicon machines.

The researchers found substantial similarities between the campaign and Atomic macOS Stealer, better known as AMOS, an infostealer previously spread through fake software downloads and malicious advertising campaigns.

Cato isn't quite ready to slap an AMOS label on the malware, but says plenty of fingerprints point in that direction, from how the attack is staged to how the final payload is built.

The crooks have also taken steps to keep researchers from getting a good look at their handiwork.