CVE-2021-23961:Firefox Slipstream Vulnerability Exposing Internal Network and Local Services

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CVE-2021-23961 affects Firefox versions prior to 85, where further techniques built on the slipstream research, when combined with a malicious webpage, could expose both internal network hosts and services running on the user's local machine. This vulnerability extends the original slipstream attack vector, potentially allowing attackers to scan and discover network resources that should be protected by network boundaries.

Overview

This vulnerability is related to the slipstream research, which demonstrated techniques for bypassing browser-based network protections. In Firefox versions before 85, a malicious webpage could leverage enhanced slipstream techniques to perform network scanning that could reveal:

  1. Internal network hosts that should be hidden from external websites
  2. Services running on the user's local machine
  3. Potentially sensitive information about the network topology

The attack requires a user to visit a specially crafted malicious webpage, which then executes code that probes the internal network or local services. This could lead to information disclosure and potentially serve as reconnaissance for further attacks.

Remediation

To address this vulnerability, users and administrators should:

  1. Update Firefox to version 85 or later, which contains patches that mitigate this vulnerability
  2. Ensure automatic updates are enabled for Firefox installations
  3. For enterprise environments, deploy the updated Firefox version through your standard software deployment mechanisms
  4. Consider implementing additional network segmentation to reduce the impact of similar browser-based attacks
  5. For Debian users, apply the security updates referenced in DSA-4895, DSA-4897, or DLA-2632-1, DLA-2633-1 as appropriate
  6. For Gentoo users, follow the guidance in GLSA-202104-09 and GLSA-202104-10

References

  1. Mozilla Security Advisory: https://www.mozilla.org/security/advisories/mfsa2021-03/
  2. Mozilla Bugzilla: https://bugzilla.mozilla.org/show_bug.cgi?id=1677940
  3. Debian Security Advisory: https://www.debian.org/security/2021/dsa-4895
  4. Debian Security Advisory: https://www.debian.org/security/2021/dsa-4897
  5. Debian LTS Announcement: https://lists.debian.org/debian-lts-announce/2021/04/msg00019.html
  6. Debian LTS Announcement: https://lists.debian.org/debian-lts-announce/2021/04/msg00020.html
  7. Gentoo Linux Security Advisory: https://security.gentoo.org/glsa/202104-09
  8. Gentoo Linux Security Advisory: https://security.gentoo.org/glsa/202104-10

Industry ExposureMost to least
This section illustrates the prevalence of a specific Common Vulnerabilities and Exposures (CVE) across various industries based on customer reports. The ranking displays industries from the most to least affected by this particular vulnerability, offering valuable insight into where this CVE has been most frequently observed. This information can help organizations within these sectors prioritize their security efforts, understand their relative risk exposure compared to their peers, and focus remediation strategies where they are most needed. By understanding the industry-specific impact, organizations can make more informed decisions regarding patching, resource allocation, and overall risk management related to this CVE.

  1. Public Administration: Medium
    Public Administration
  2. Manufacturing: Medium
    Manufacturing
  3. Health Care & Social Assistance: Medium
    Health Care & Social Assistance
  4. Educational Services: Medium
    Educational Services
  5. Transportation & Warehousing: Medium
    Transportation & Warehousing
  6. Finance and Insurance: Medium
    Finance and Insurance
  7. Retail Trade: Medium
    Retail Trade
  8. Professional, Scientific, & Technical Services: Medium
    Professional, Scientific, & Technical Services
  9. Arts, Entertainment & Recreation: Low
    Arts, Entertainment & Recreation
  10. Other Services (except Public Administration): Low
    Other Services (except Public Administration)
  11. Utilities: Low
    Utilities
  12. Information: Low
    Information
  13. Management of Companies & Enterprises: Low
    Management of Companies & Enterprises
  14. Accommodation & Food Services: Low
    Accommodation & Food Services
  15. Agriculture, Forestry Fishing & Hunting: Low
    Agriculture, Forestry Fishing & Hunting
  16. Real Estate Rental & Leasing: Low
    Real Estate Rental & Leasing
  17. Mining: Low
    Mining
  18. Construction: Low
    Construction
  19. Administrative, Support, Waste Management & Remediation Services: Low
    Administrative, Support, Waste Management & Remediation Services
  20. Wholesale Trade: Low
    Wholesale Trade

Focus on What Matters

  1. See Everything.
  2. Identify True Risk.
  3. Proactively Mitigate Threats.

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