Maccy Users Targeted by New Rust-Based Infostealer, PamStealer

Mac users searching for the open-source clipboard manager Maccy are being targeted by a fake version of the app that installs a new Rust-based infostealer dubbed PamStealer, according to cybersecurity firm Jamf Threat Labs.

If successful, the malware could steal users’ passwords and crypto wallet keys.

In a report published on Thursday, Jamf Threat Labs said the campaign uses a lookalike website to distribute a disk image containing a malicious AppleScript file named Maccy.scpt. When opened, the file displays instructions telling users to run it in Apple's Script Editor while hiding the malicious code further down the document.

“We are tracking this malware under the name PamStealer after one of its core behaviors: validating the victim’s login password through the macOS Pluggable Authentication Modules (PAM) before harvesting it,” Jamf Threat Labs wrote.

From there, the malware uses JavaScript for Automation and native macOS APIs to download a second-stage payload without relying on common shell utilities such as curl or zsh, reducing the number of processes security tools can observe.

"With many stealers, we have seen attackers purchasing Google Ad space to lure users to the malicious app. We have recently observed malicious ads being hosted on X as well,” Jamf Threat Labs Director Jaron Bradley told Decrypt. “These social engineering techniques have proven to be highly successful."

According to the report, the second stage is a Rust-based binary designed for Apple Silicon Macs that disguises itself as Finder or Software Update.

“Rather than storing its configuration in cleartext, the dropper derives a key from a fingerprint of the host—including its CPU architecture, locale, keyboard layout, and time zone—and uses it to unlock an encrypted, integrity-checked configuration containing the payload URL and installation path,” the company said.

Once installed, the malware can steal browser credentials and Keychain data, monitor clipboard contents, establish persistence, and send stolen information to a remote command-and-control server using encrypted communications. If it can't verify that it's running on its intended target, then it quietly shuts itself down.

The malware also attempts to expand its access by displaying a fake Finder alert asking users to grant Full Disk Access. The prompt can appear up to 40 minutes after infection, making it less likely that users will associate it with the original download. If approved, the malware can access protected data, including Mail, Messages, and Time Machine backups.

According to Bradley, Jamf has not observed any evidence that PamStealer is active in the wild; however, the company notified Apple of its findings. Apple did not immediately respond to a request for comment by Decrypt.

Jamf said it is seeing similar social engineering techniques spread to other platforms.

In an X post last week, the company said it was investigating a sponsored advertisement on X promoting DynamicLake that redirected users to dynamicmacisland[.]com, where they were instructed to open Terminal and execute an installation command.

“The advertisement was delivered through a verified X account, adding another layer of trust to the social engineering,” the firm wrote. “Analysis of the payload revealed a recent Atomic (MacSync) Stealer variant.”