Firefox must be configured to block pop-up windows.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-251553 | FFOX-00-000009 | SV-251553r960963_rule | CCI-000381 | medium |
| Description | ||||
| Pop-up windows may be used to launch an attack within a new browser window with altered settings. This setting blocks pop-up windows created while the page is loading. | ||||
| STIG | Date | |||
| Mozilla Firefox Security Technical Implementation Guide | 2025-02-11 | |||
Details
Check Text (C-251553r960963_chk)
Type "about:policies" in the browser address bar.
If "PopupBlocking" is not displayed under Policy Name or the Policy Value is not "Default" "true", this is a finding.
If "PopupBlocking" is not displayed under Policy Name or the Policy Value is not "Locked" "true", this is a finding.
"PopupBlocking" "Enabled" may be used to specify an allowlist of sites where pop-ups are desired, this is optional.
Fix Text (F-54942r862957_fix)
Windows group policy:
1. Open the group policy editor tool with "gpedit.msc".
2. Navigate to Policy Path: Computer Configuration\Administrative Templates\Mozilla\Firefox\Popups
Policy Name: Block pop-ups from websites
Policy State: Enabled
Policy Name: Do not allow preferences to be changed
Policy State: Enabled
Optional:
Policy Name: Allowed Sites
Policy State: Enabled
Click "Show..." and enter a list of websites to be allowlisted.
macOS "plist" file:
Add the following:
<key>PopupBlocking</key>
<dict>
<key>Allow</key>
<array>
<string>http://example.mil</string>
<string>http://example.gov</string>
</array>
<key>Default</key>
<true/>
<key>Locked</key>
<true/>
</dict>
Linux "policies.json" file:
Add the following in the policies section:
"PopupBlocking": {
"Allow": ["http://example.mil/",
"http://example.gov/"],
"Default": true,
"Locked": true}