Posted by Ben Ackerman, Chrome team, Daniel Rubery, Chrome team and Guillaume Ehinger, Google Account Security team Following our April 2024 announcement , Device Bound Session Credentials (DBSC) is now entering public availability for Windows users on Chrome 146, and expanding to macOS in an upcoming Chrome release. This project represents a significant step forward in our ongoing efforts to combat session theft, which remains a prevalent threat in the modern security landscape. Session theft typically occurs when a user inadvertently downloads malware onto their device. Once active, the malware can silently extract existing session cookies from the browser or wait for the user to log in to new accounts, before exfiltrating these tokens to an attacker-controlled server. Infostealer malware families, such as LummaC2, have become increasingly sophisticated at harvesting these credentials. Because cookies often have extended lifetimes, attackers can use them to gain unauthorized access to a user’s accounts without ever needing their passwords; this access is then often bundled, traded, or sold among threat actors. Crucially, once sophisticated malware has gained access to a machine, it can read the local files and memory where browsers store authentication cookies. As a result, there is no reliable way to prevent cookie exfiltration using software alone on any operating system. Historically, mitigating session theft relied on detecting the stolen credentials after the fact using a complex set of abuse heuristics – a reactive approach that persistent attackers could often circumvent. DBSC fundamentally changes the web's capability to defend against this threat by shifting the paradigm from reactive detection to proactive prevention, ensuring that successfully exfiltrated c