Executive Summary

CVE-2025-49710 represents a critical security vulnerability within Mozilla Firefox versions prior to 139.0.4, specifically affecting the OrderedHashTable utilized by the JavaScript engine. This integer overflow vulnerability has been assigned a CVSS score of 9.8, indicating a high likelihood of exploitation with minimal complexity and no authentication requirements. Given the nature of the vulnerability, it poses a significant risk to organizational security, particularly in environments where Firefox is widely used. The potential for exploitation by advanced persistent threat (APT) groups and ransomware operators necessitates immediate attention and remediation.

Technical Severity Assessment

  • CVSS Score: 9.8/10.0
  • Attack Vector: Network-based, allowing remote exploitation.
  • Attack Complexity: Low, indicating ease of exploitation.
  • Authentication: None required, enabling unauthenticated attacks.
  • User Interaction: Not needed, facilitating automated exploitation.

Real-World Impact Analysis

The vulnerability's critical classification suggests that it could be leveraged in widespread attacks, potentially leading to unauthorized access, data exfiltration, or system compromise. Organizations utilizing affected versions of Firefox should prioritize patching to mitigate the risk associated with this vulnerability.

Vulnerability Deep Dive

Root Cause Analysis

The vulnerability arises from an integer overflow in the OrderedHashTable implementation within the JavaScript engine of Firefox. This data structure is essential for managing key-value pairs efficiently, but the overflow can lead to memory corruption, allowing an attacker to execute arbitrary code.

Code Review

The specific code path leading to the vulnerability has not been publicly disclosed in detail. However, based on similar vulnerabilities in hash table implementations, we can infer that the overflow occurs during the resizing of the hash table when the number of entries exceeds a certain threshold. 

// Hypothetical example of a vulnerable hash table resizing function
void resize_hash_table(OrderedHashTable *table) {
    size_t new_size = table->size * 2; // Potential overflow if size is large
    if (new_size < table->size) {
        // Overflow occurred, leading to a smaller than expected size
        // This can lead to memory corruption when reallocating
    }
    table->entries = realloc(table->entries, new_size * sizeof(Entry));
}

Assembly-Level Analysis

While the exact assembly code for the vulnerable function is not available, similar vulnerabilities typically involve the following assembly instructions:

  • MOV: Moving values into registers.
  • ADD: Adding values that may lead to overflow.
  • CALL: Invoking functions that manipulate memory based on the overflowed value.

Memory Corruption Mechanics

The integer overflow can lead to a corrupted memory layout, allowing an attacker to overwrite critical data structures. This can be visualized as follows:

+---------------------+
| OrderedHashTable    |
+---------------------+
| size                |  <-- Overflow occurs here
+---------------------+
| entries (pointer)   |
+---------------------+
| ...                 |
+---------------------+

Technical Mechanism

The exploitation mechanics involve manipulating the input to the JavaScript engine to trigger the overflow condition. An attacker could craft a malicious script that, when executed, causes the OrderedHashTable to exceed its intended size, leading to memory corruption and potential code execution.

Step-by-Step Memory Layout Changes

  1. Initial State: The hash table is allocated with a certain size.
  2. Overflow Trigger: An attacker inputs data that causes the size calculation to overflow.
  3. Memory Reallocation: The realloc function is called with the corrupted size, leading to a smaller allocation than required.
  4. Memory Overwrite: Subsequent operations on the hash table overwrite adjacent memory, potentially leading to arbitrary code execution.

Attack Prerequisites

  • Affected Versions: Mozilla Firefox versions < 139.0.4.
  • Configuration: Default settings are likely sufficient for exploitation.
  • Network Positioning: The attacker must be able to deliver a malicious payload via the network.
  • Timing Windows: The attack can be executed in a single request without requiring user interaction.

Threat Intelligence

Known Exploitation

As of the publication date, there are no confirmed reports of active exploitation. However, the high CVSS score and critical severity suggest that exploitation is likely to occur soon after disclosure.

Threat Actor Activity

Given the nature of the vulnerability, it is anticipated that APT groups and ransomware operators may target it. The lack of authentication requirements and the potential for remote exploitation make it an attractive vector for attackers.

Attack Patterns

Potential attack methodologies include:
- Web-based attacks: Leveraging malicious JavaScript embedded in web pages.
- Phishing campaigns: Distributing links to compromised sites that exploit the vulnerability.

Technical Analysis

Proof of Concept

While specific PoC code is not yet available, the following is a hypothetical example of how an attacker might exploit the vulnerability:

// Hypothetical PoC for triggering the integer overflow
let hashTable = new OrderedHashTable();
for (let i = 0; i < Number.MAX_SAFE_INTEGER; i++) {
    hashTable.set(i, "value");
}
// This could trigger the overflow during resizing

Exploitation Techniques

  1. Direct Memory Manipulation: Overwriting function pointers in memory.
  2. Return-Oriented Programming (ROP): Constructing a ROP chain to execute arbitrary code.
  3. Heap Spraying: Filling the heap with shellcode to increase the chances of execution.
  4. JavaScript Injection: Using crafted scripts to manipulate the JavaScript engine directly.
  5. Network-Based Exploitation: Sending specially crafted requests to trigger the overflow.

Bypass Methods

  • WAF Evasion: Crafting payloads that bypass web application firewalls.
  • Obfuscation Techniques: Using obfuscated JavaScript to evade detection.

Detection & Response

Behavioral Indicators

  • Process Behavior: Monitoring for unusual memory allocation patterns.
  • Network Traffic Patterns: Analyzing traffic for known exploit signatures.

Forensic Artifacts

  • Memory Dumps: Analyzing memory for signs of exploitation.
  • Log Analysis: Identifying unusual access patterns in server logs.

Hunting Queries

  • Splunk Query: 
index=firefox_logs sourcetype=access | stats count by user_agent | where user_agent="Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.3"

Mitigation Engineering

Immediate Actions

  1. Update Firefox: Ensure all users are upgraded to version 139.0.4 or later.
  2. Network Segmentation: Limit access to vulnerable systems.

Long-term Hardening

  • Security Policies: Implement strict browser usage policies.
  • User Education: Train users to recognize phishing attempts.

Architectural Improvements

  • Code Audits: Regularly review code for similar vulnerabilities.
  • Security Testing: Integrate security testing into the development lifecycle.

Real-World Impact

Case Studies

  • Incident Timeline: Documenting the timeline of discovery and patching.
  • Financial Impact: Estimating potential losses from exploitation.

Business Risk

  • Compliance Implications: Assessing the impact on regulatory compliance.
  • Reputation Damage: Evaluating the potential damage to organizational reputation.

Industry Analysis

  • Vertical-Specific Attack Scenarios: Understanding how different industries may be targeted.

Intelligence Outlook

Threat Evolution

  • Predictive Threat Modeling: Anticipating future exploitation techniques based on this vulnerability.
  • Comparison with Similar CVEs: Analyzing patterns in integer overflow vulnerabilities.

Future Considerations

  • Long-term Remediation Roadmap: Establishing a plan for ongoing security improvements.

This analysis provides a comprehensive overview of CVE-2025-49710, detailing the vulnerability's mechanics, potential exploitation methods, detection strategies, and mitigation techniques. Further research and monitoring are recommended to stay ahead of potential exploitation attempts.