A vulnerability in the Steam client allowed a normal user to gain elevated access to a highly privileged account, impacting 96 million gamers. This security bug is widespread and difficult to address. Let's find out how to stop and remediate this bug.
In August 2019, a vulnerability in Steam's Windows client was exposed, enabling a regular user to escalate their privileges to a high-privileged account, affecting 96 million gamers. The flaw exploited the Steam client service's SYSTEM privileges, which copied a DLL from a writable user-accessible path during startup. The service's signature verification failed to prevent the execution of tampered DLL files.
Let’s head to the lab to discover, debug, and fix this vulnerability within an actual application.
TOCTOU, a race condition bug, occurs when the verification and utilisation of a program's state occur in separate calls, potentially leading to authorisation bypass or unexpected outcomes due to changes in the program state between these actions.
