CVE-2024-11697: Mozilla Firefox RCE Vulnerability

CVE-2024-11697 Overview

CVE-2024-11697 is a security bypass vulnerability affecting Mozilla Firefox and Thunderbird that allows attackers to trick users into bypassing the "Open Executable File?" confirmation dialog through improper handling of keypress events. When exploited, this vulnerability could lead to malicious code execution on the victim's system without proper user authorization.

Critical Impact

Attackers can leverage specially crafted keypress events to bypass security confirmation dialogs, potentially leading to unauthorized execution of malicious executables on target systems.

Affected Products

• Mozilla Firefox versions prior to 133
• Mozilla Firefox ESR versions prior to 128.5
• Mozilla Thunderbird versions prior to 133 and prior to 128.5

Discovery Timeline

• 2024-11-26 - CVE-2024-11697 published to NVD
• 2025-11-03 - Last updated in NVD database

Technical Details for CVE-2024-11697

Vulnerability Analysis

This vulnerability is classified as CWE-94 (Improper Control of Generation of Code, also known as Code Injection). The flaw resides in how Mozilla Firefox and Thunderbird handle keypress events during file download operations. Under normal circumstances, when a user attempts to open an executable file, the browser presents a confirmation dialog asking whether the user wants to proceed with opening the potentially dangerous file. This dialog serves as a critical security boundary to prevent accidental execution of malicious content.

The vulnerability allows an attacker to manipulate keypress event handling in a way that causes the confirmation dialog to be bypassed entirely. By exploiting the timing and sequence of keyboard events, an attacker can trick the browser into interpreting user input in an unintended manner, effectively auto-confirming the execution of downloaded files without the user's explicit consent.

Root Cause

The root cause of CVE-2024-11697 lies in improper validation and handling of keypress events within the file download confirmation workflow. The browser fails to adequately distinguish between legitimate user-initiated keystrokes intended to respond to the confirmation dialog and attacker-controlled keypress events that could be injected or manipulated through malicious web content. This race condition or event-handling flaw allows the security dialog to be circumvented.

Attack Vector

The attack is network-based and requires user interaction. An attacker would need to:

1. Host malicious web content that initiates a download of an executable file
2. Craft the webpage to manipulate keypress event handling during the download process
3. Trick the user into visiting the malicious page and interacting with it in a way that triggers the exploit
4. The manipulated keypress events cause the browser to bypass the "Open Executable File?" confirmation

The exploitation does not require privileges on the target system, making it accessible to remote attackers who can deliver the malicious content via phishing emails, compromised websites, or malicious advertisements.

The vulnerability mechanism involves manipulating the keypress event queue during the critical moment when the confirmation dialog should be displayed. Technical details are available in Mozilla Bug Report #1842187 and the associated security advisories.

Detection Methods for CVE-2024-11697

Indicators of Compromise

• Unexpected executable files appearing in download directories without user-initiated confirmation
• Browser process spawning child processes for executable files without corresponding user interaction logs
• Network traffic patterns showing rapid download and execution sequences from suspicious domains
• Anomalous keypress event patterns in browser telemetry or forensic analysis

Detection Strategies

• Monitor for executable file downloads followed by immediate execution without typical user confirmation delays
• Implement endpoint detection rules to flag browser-initiated process execution chains
• Deploy network monitoring to identify domains known to host CVE-2024-11697 exploit kits
• Utilize browser extension or policy controls to log and alert on executable downloads

Monitoring Recommendations

• Enable enhanced logging for browser download activities and file execution events
• Configure SIEM rules to correlate download events with subsequent process creation
• Monitor browser version telemetry across the organization to identify unpatched instances
• Review endpoint detection and response (EDR) alerts for suspicious parent-child process relationships involving Firefox or Thunderbird

How to Mitigate CVE-2024-11697

Immediate Actions Required

• Update Mozilla Firefox to version 133 or later immediately
• Update Mozilla Firefox ESR to version 128.5 or later
• Update Mozilla Thunderbird to version 133 or 128.5 or later
• Prioritize updates for systems where users frequently interact with external web content or email attachments

Patch Information

Mozilla has released security patches addressing CVE-2024-11697 in the following versions:

• Firefox 133 and Firefox ESR 128.5 contain the fix for this vulnerability
• Thunderbird 133 and Thunderbird 128.5 include the necessary security corrections

Organizations should apply these updates through their standard software deployment mechanisms. For detailed patch information, refer to Mozilla Security Advisory MFSA-2024-63, MFSA-2024-64, MFSA-2024-67, and MFSA-2024-68. Debian users should also review the Debian LTS Announcement for distribution-specific guidance.

Workarounds

• Configure browser policies to block automatic execution of downloaded files entirely
• Implement application whitelisting to prevent unauthorized executable execution
• Deploy web filtering solutions to block access to known malicious sites
• Educate users about the risks of interacting with unexpected download prompts

# Firefox Enterprise Policy Configuration (policies.json)
# Place in Firefox installation directory under /distribution/
# This disables automatic opening of downloaded files
{
  "policies": {
    "DisableAppUpdate": false,
    "Handlers": {
      "mimeTypes": {
        "application/x-msdownload": {
          "action": "saveToDisk"
        }
      }
    },
    "PromptForDownloadLocation": true
  }
}