Threat Watch

Steam Zero-Day Vulnerability

The popular game client for Windows, called Steam, has been found to have a privilege escalation vulnerability. A privilege escalation bug is a flaw that allows a user with limited rights to launch an executable with elevated levels of privileges–even as high as administrator. With Steam having over 100 million downloads and having millions of users online at all times, this is a serious flaw that can be abused by malware to perform a multitude of malicious actions. Two independent researchers have confirmed this flaw through a Proof-of-Concept (POC). The POC showed that when the service is started and stopped, it gave full write access to the subkeys which when modified would allow an attacker to give themselves system privileges that can launch other programs with elevated rights. A second researcher created a POC that exploits this flaw so that the bug can change the executable when the service is launched. An attacker could change the executable to deliver any sort of malicious program.


Steam has yet to respond to these notifications so there is no news on a security patch. If a user has this on their system, they are recommended to only use it behind a Virtual Private Network (VPN) and to have the user’s malware and virus detection set to automatically update in an effort to have the latest information.