As part of further "refinements in its tactics," a malware notorious for targeting the macOS operating system has been updated to add more elements to its toolset that allow it to accumulate and exfiltrate sensitive data saved in a range of programmes, including apps like Google Chrome and Telegram. This macOS malware can collect login credentials from a variety of apps, allowing its operators to steal accounts. 

XCSSET was discovered in August 2020, when it was found to be targeting Mac developers using an unusual method of propagation that entailed injecting a malicious payload into Xcode IDE projects, which is executed when the project files are built in Xcode. XCSSET collects files containing sensitive information from infected computers and delivers them to the command and control (C2) server. 

Telegram, an instant messaging service, is one of the apps that has been attacked. The virus produces the “telegram.applescript” archive in the Group Containers directory for the “keepcoder.Telegram” folder. By obtaining the Telegram folder, the hackers are able to log into the messaging app as the account's legal owner. The attackers gain access to the victim's account by moving the stolen folder to another machine with Telegram installed, according to Trend Micro researchers. Normal users have read and write permissions to the Application sandbox directory, XCSSET can steal sensitive data this way. 

The malware can read and dump Safari cookies, inject malicious JavaScript code into multiple websites, steal information from programmes like Notes, WeChat, Skype, and Telegram, and encrypt user files, among other things. Earlier this month, XCSSET received an update that allowed malware developers to target macOS 11 Big Sur as well as Macs with the M1 chipset by getting beyond Apple's new security standards in the current operating system. 

"The malware downloads its own open tool from its C2 server that comes pre-signed with an ad-hoc signature, whereas if it were on macOS versions 10.15 and lower, it would still use the system's built-in open command to run the apps," Trend Micro researchers previously noted. 

According to a new report released by the cybersecurity firm on Thursday, XCSSET uses a malicious AppleScript file to compress the Telegram data folder ("/Library/Group Containers/6N38VWS5BX.ru.keepcoder.Telegram") into a ZIP archive file before uploading it to a remote server under their control, allowing the threat actor to log in using the victim's account. 

"The discovery of how it can steal information from various apps highlights the degree to which the malware aggressively attempts to steal various kinds of information from affected systems," the researchers said.