ASUS’ update mechanism has once again been abused to install malware that backdoors PCs, researchers from Eset reported earlier this week. The researchers, who continue to investigate the incident, said they believe the attacks are the result of router-level man-in-the-middle attacks that exploit insecure HTTP connections between end users and ASUS servers, along with incomplete code-signing to validate the authenticity of received files before they’re executed.
Plead, as the malware is known, is the work of espionage hackers Trend Micro calls the BlackTech Group, which targets government agencies and private organizations in Asia. Last year, the group used legitimate code-signing certificates stolen from router-maker D-Link to cryptographically authenticate itself as trustworthy. Before that, the BlackTech Group used spear-phishing emails and vulnerable routers to serve as command-and-control servers for its malware.
Late last month, Eset researchers noticed the BlackTech Group was using a new and unusual method to sneak Plead onto targets’ computers. The backdoor arrived in a file named
ASUS Webstorage Upate.exe included in an update from ASUS. An analysis showed infections were being created and executed by
AsusWSPanel.exe, which is a legitimate Windows process belonging to, and digitally signed by, ASUS WebStorage. As the name suggests, ASUS WebStorage is a cloud service the computer maker offers for storing files.