![]() For instance, in a default launch of Chrome, you’ll see that the main browser process launches at the default (“Medium”) Integrity Level, while the GPU process runs at Low Integrity, and the Renderer processes run at Untrusted Integrity (the lowest): You’ll note that browsers typically use multiple processes with different sandboxing restrictions attached to each. For instance, you can see the Windows Job restrictions applied to this Edge Renderer Process: Tools like SysInternals’ Process Explorer allow inspecting some of the sandboxing limitations applied to browsers’ processes. Google Chrome and later versions of IE went much further, with AppContainers and broader process restrictions to make exploitation more challenging and reduce its impact. Internet Explorer 7 built atop the UAC Integrity Levels system and introduced the notion of “Protected Mode” whereby Internet Zone content ran inside a tighter sandbox with decreased write-access to the system. Windows Vista introduced the notion of UAC Integrity Levels, whereby each system object (including processes) had an integrity level that limited the other objects it could read and write. Process sandboxing arose in the mid-200Xs as a defense-in-depth against Design Sandboxing mistakes – any error in implementation meant that an attacker could achieve arbitrary code execution (RCE) and take over the victim user’s computer. ![]() As a consequence, most real-world browser attacks now must include exploits for two vulnerabilities: the original RCE, and a Sandbox Escape.Ī web browser uses multiple mechanisms for sandboxing, from “Design sandboxing” ( Same-Origin-Policy, limited JavaScript capabilities) to Process Sandboxing (AppContainers, UAC Integrity Levels, Restricted Tokens, etc) to optional VM sandboxing ( WDAG).
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