Title

Firefox must be configured to prevent JavaScript from moving or resizing windows. (Cat II impact)

Discussion

JavaScript can make changes to the browser's appearance. This activity can help disguise an attack taking place in a minimized background window. Configure the browser setting to prevent scripts on visited websites from moving and resizing browser windows.

Check Content

Type "about:policies" in the browser address bar. If "dom.disable_window_move_resize" is not displayed with a value of "true", this is a finding.

Fix Text

Windows group policy: 1. Open the group policy editor tool with "gpedit.msc". 2. Navigate to Policy Path: Computer Configuration\Administrative Templates\Mozilla\Firefox\ Policy Name: Preferences Policy State: Enabled Policy Value: { "dom.disable_window_move_resize": { "Value": true, "Status": "locked" } } macOS "plist" file: Add the following: <key>Preferences</key> <dict> <key>dom.disable_window_move_resize</key> <dict> <key>Value</key> <true/> <key>Status</key> <string>locked</string> </dict> </dict> Linux "policies.json" file: Add the following in the policies section: "Preferences": { "dom.disable_window_move_resize": { "Value": true, "Status": "locked" } }

Additional Identifiers

Rule ID: SV-251554r879587_rule

Vulnerability ID: V-251554

Group Title: SRG-APP-000141

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.