SV-251554r1067554: Firefox must be configured to prevent JavaScript from moving or resizing windows. | Mozilla Firefox for Linux STIG SCAP Benchmark

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Assessment Title

Rule Text

Firefox must be configured to prevent JavaScript from moving or resizing windows.

Description

Discussion Text

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.

How this relates to the STIG checklist: STIG vs SCAP benchmark.

IA Controls

NIST SP 800-53

Not mappedCCI-000381

References

DPMS Target Mozilla Firefox 2021 VERSION DISA DPMS Target Mozilla Firefox 2021 VERSION 5446

SCC Automation Reference

The reconstructed evaluation script behind this rule's OVAL check(s) — every module a compound check combines, with this rule's own concrete values and DISA's SCC tool's real per-module mechanism curated from static teardown of SCC releases.

Assessment Script Powered by AISandbox-executed

A standalone Shell script to assess this control automatically. Review before running it in your environment.

Syntax-checked and actually executed in an isolated sandbox (not the real system this checks) — confirmed to run without errors.

#!/bin/sh
# DISA STIG / SCAP compliance check for Firefox: oval:mil.disa.stig.firefox.linux:def:109

if [ -f /path/to/policies.json ]; then
    grep -q '"dom.disable_window_move_resize":{"Value":true' /path/to/policies.json && \
    grep -q '"dom.disable_window_move_resize":{"Status":"locked' /path/to/policies.json && \
    echo "PASS" && exit 0
else
    echo "FAIL" && exit 1
fi

Remediation

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"
  }
}