Microsoft Windows DNS Server Remote Code Execution Vulnerability SigRed (CVE-2020-1350) Threat Alert

Microsoft Windows DNS Server Remote Code Execution Vulnerability SigRed (CVE-2020-1350) Threat Alert

agosto 11, 2020 | Mina Hao

Overview

On July 14, 2020 local time, Microsoft addressed a wormable Windows DNS server vulnerability dubbed SigRed (CVE-2020-1350) in its latest monthly patch updates. Once exploited by attackers, the vulnerability could spread between vulnerable computers without user interaction, thereby probably infecting the network of the whole organization.

It is reported that the vulnerability has existed for 17 years and assigns a score of 10 (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H/E:P/RL:O/RC:C).

When a DNS server parses uploaded queries or responds to forwarded requests, the vulnerability could be exploited.

Check Point researchers found that sending DNS responses containing SIG records (greater than 64 KB) could cause a stack-based buffer overflow, further allowing attackers to control a server.

Reference link:

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-1350

Affected Versions

  • Windows Server 2008 for 32-bit Systems Service Pack 2
  • Windows Server 2008 for 32-bit Systems Service Pack 2 (Server Core installation)
  • Windows Server 2008 for x64-based Systems Service Pack 2
  • Windows Server 2008 for x64-based Systems Service Pack 2 (Server Core installation)
  • Windows Server 2008 R2 for x64-based Systems Service Pack 1
  • Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation)
  • Windows Server 2012
  • Windows Server 2012 (Server Core installation)
  • Windows Server 2012 R2
  • Windows Server 2012 R2 (Server Core installation)
  • Windows Server 2016
  • Windows Server 2016 (Server Core installation)
  • Windows Server 2019
  • Windows Server 2019 (Server Core installation)
  • Windows Server, version 1909 (Server Core installation)
  • Windows Server, version 1903 (Server Core installation)
  • Windows Server, version 2004 (Server Core installation)

Solution

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-1350

Before applying the patches, you are advised to set the maximum length of DNS messages (via TCP) to 0xFF00 to mitigate the vulnerability. This can be achieved by running the following command:

reg add "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\DNS\Parameters" /v "TcpReceivePacketSize" /t REG_DWORD /d 0xFF00 /f

net stop DNS && net start DNS

Meanwhile, you are advised to set the DNS server as the trusted server.

Statement

This advisory is only used to describe a potential risk. NSFOCUS does not provide any commitment or promise on this advisory. NSFOCUS and the author will not bear any liability for any direct and/or indirect consequences and losses caused by transmitting and/or using this advisory. NSFOCUS reserves all the rights to modify and interpret this advisory. Please include this statement paragraph when reproducing or transferring this advisory. Do not modify this advisory, add/delete any information to/from it, or use this advisory for commercial purposes without permission from NSFOCUS.

About NSFOCUS

NSFOCUS, Inc., a global network and cyber security leader, protects enterprises and carriers from advanced cyber attacks. The company’s Intelligent Hybrid Security strategy utilizes both cloud and on-premises security platforms, built on a foundation of real-time global threat intelligence, to provide multi-layered, unified and dynamic protection against advanced cyber attacks.

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