301.519.9237 exdirector@nesaus.org

1.30.20 – SSI Staff – ARLINGTON, Va.

The flaw makes Windows 10 and Windows Server 2016/2019 “fundamentally vulnerable,” according to a National Security Agency advisory.

The Cybersecurity and Infrastructure Security Agency (CISA) released an Emergency Directive and Activity Alert addressing critical vulnerabilities affecting Windows CryptoAPI, Windows Remote Desktop Gateway (RD Gateway) and Windows Remote Desktop Client.

CISA officials say a remote attacker could exploit these vulnerabilities to decrypt, modify or inject data on user connections.

Although Emergency Directive 20-02 applies only to certain executive branch departments and agencies, CISA strongly recommends state and local governments, the private sector and others also patch these critical vulnerabilities as soon as possible.

The National Security Agency (NSA) notified Microsoft of the vulnerability, and Microsoft released software fixes, which can be found here.

According to the NSA, the certificate validation vulnerability allows an attacker to undermine how Windows verifies cryptographic trust and can enable remote code execution. The vulnerability affects Windows 10 and Windows Server 2016/2019 as well as applications that rely on Windows for trust functionality.

Exploitation of the vulnerability allows attackers to defeat trusted network connections and deliver executable code while appearing as legitimately trusted entities. Examples where validation of trust may be impacted include:

  • HTTPS connections
  • Signed files and emails
  • Signed executable code launched as user-mode processes

The vulnerability places Windows endpoints at risk to a broad range of exploitation vectors. NSA assesses the vulnerability to be severe and that sophisticated cyber actors will understand the underlying flaw very quickly and, if exploited, would render the previously mentioned platforms as fundamentally vulnerable.

Both the NSA and CISA recommend that organizations immediately install patches as soon as possible. In the event that enterprise-wide, automated patching is not possible, NSA recommends system owners prioritize patching endpoints that provide essential or broadly replied-upon services.