CVE-2023-28451:BadDNS vulnerability in Technitium DNS Server 11.0.2 allows attackers to cause denial of service by forcing resolvers to ignore valid DNS responses.

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A vulnerability known as BadDNS was discovered in Technitium DNS Server version 11.0.2. This security flaw allows attackers to interfere with the DNS resolution process by sending forged responses that target the source port of vulnerable resolvers. The attack doesn't require guessing the correct transaction ID (TXID), making it relatively easy to execute. When exploited, the resolver ignores legitimate DNS responses, causing a denial of service condition that prevents normal DNS resolution. The impact of this vulnerability is considered widespread and highly impactful as it affects a core networking function that many systems depend on.

Overview

The BadDNS vulnerability (CVE-2023-28451) affects Technitium DNS Server 11.0.2, a popular open-source DNS server implementation. The vulnerability exists in the DNS resolution process where the server fails to properly validate incoming DNS responses. An attacker can exploit this by crafting malicious DNS responses targeting the source port of a vulnerable resolver. Unlike traditional DNS spoofing attacks that require guessing both the source port and transaction ID, this attack only needs to target the source port, significantly lowering the barrier for exploitation. When successful, the attack causes the DNS resolver to discard legitimate responses, resulting in DNS resolution failures for clients. This effectively creates a denial of service condition that can disrupt network communications for all systems relying on the affected DNS resolver.

Remediation

To mitigate this vulnerability, system administrators should take the following actions:

  1. Update Technitium DNS Server to the latest version beyond 11.0.2 that contains patches for this vulnerability.
  2. If immediate updating is not possible, consider implementing network-level protections:
    • Use firewall rules to restrict which external DNS servers can communicate with your resolver
    • Implement DNS response rate limiting to mitigate the impact of attack attempts
    • Consider deploying DNSSEC where possible to provide additional authentication for DNS responses
  3. Monitor DNS server logs for unusual patterns of failed resolutions that might indicate an ongoing attack
  4. Consider using alternative DNS resolvers temporarily if you cannot update and are experiencing attacks
  5. Follow the Technitium project's security announcements for additional guidance specific to this vulnerability

References

  1. Vulnerability Details: https://gist.github.com/idealeer/89947ca07836fd0f7e9761198ca9a0f3
  2. Technitium DNS Server Official Website: https://technitium.com/dns/
  3. CVE-2023-28451 in the National Vulnerability Database
  4. MITRE CVE Record: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-28451

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

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