Added impersonation of the anonymous token around CloseClipboard

ui/base/clipboard/clipboard_win.cc

Index: ui/base/clipboard/clipboard_win.cc
diff --git a/ui/base/clipboard/clipboard_win.cc b/ui/base/clipboard/clipboard_win.cc
index c2c2fb69f8e3f845e1ec28cedeb9a2de72bb2a9b..1044c3f1951809bef6a25abd87baa739b4a46b09 100644
--- a/ui/base/clipboard/clipboard_win.cc
+++ b/ui/base/clipboard/clipboard_win.cc
@@ -35,6 +35,22 @@ namespace ui {
 
 namespace {
 
+// A scoper to impersonate the anonymous token and revert when leaving scope
+class AnonymousImpersonator {
+ public:
+  AnonymousImpersonator() {
+    must_revert_ = ::ImpersonateAnonymousToken(::GetCurrentThread());
+  }
+
+  ~AnonymousImpersonator() {
+    if (must_revert_)
+      ::RevertToSelf();
+  }
+
+ private:
+  BOOL must_revert_;

[dcheng, 2014/12/13 01:16:50]

Actually, you probably want DISALLOW_COPY_AND_ASSIGN here, just in case.

+};
+
 // A scoper to manage acquiring and automatically releasing the clipboard.
 class ScopedClipboard {
  public:
@@ -84,6 +100,11 @@ class ScopedClipboard {
 
   void Release() {
     if (opened_) {
+      // Impersonate the anonymous token during the call to CloseClipboard
+      // This prevents Windows 8+ capturing the broker's access token which
+      // could be accessed by lower-privileges chrome processes leading to
+      // a risk of EoP
+      AnonymousImpersonator impersonator;
       ::CloseClipboard();
       opened_ = false;
     } else {