Firefox must be configured to block pop-up windows.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-251553	FFOX-00-000009	SV-251553r879587_rule		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	2023-06-05

Details

Check Text ( C-54988r820748_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.

Check Text ( C-54988r820748_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: PopupBlocking Allow http://example.mil http://example.gov Default Locked Linux "policies.json" file: Add the following in the policies section: "PopupBlocking": { "Allow": ["http://example.mil/", "http://example.gov/"], "Default": true, "Locked": true}

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:
PopupBlocking

Allow

http://example.mil
http://example.gov

Default

Locked

Linux "policies.json" file:
Add the following in the policies section:
"PopupBlocking": {
"Allow": ["http://example.mil/",
"http://example.gov/"],
"Default": true,
"Locked": true}