Microsoft Windows Remote Desktop Gateway contains vulnerabilities that may allow a remote, unauthenticated attacker to execute arbitrary code with SYSTEM privileges on a vulnerable system.
Microsoft Windows Remote Desktop Gateway (RD Gateway) is a Windows Server component that provides access to Remote Desktop services without requiring the client system to be present on the same network as the target system. Originally launched as Terminal Services Gateway (TS Gateway) with Windows Server 2008, RD Gateway is a recommended way to provide Remote Desktop connectivity to cloud-based systems. For example, guidance has been provided for using RD Gateway with AWS, and also with Azure. The use of RD Gateway is recommended to reduce the attack surface of Windows-based hosts.
Microsoft RD Gateway in Windows Server 2012 and later contain two vulnerabilities that can allow an unauthenticated remote attacker to execute arbitrary code with SYSTEM privileges. It is reported by Kryptos Logic that the flaws lie in handling of fragmentation. This vulnerability is exploitable by connecting to the RD Gateway service listening on UDP/3391.
By sending a specially-crafted request to a Remote Desktop Gateway server, an unauthenticated remote attacker to execute arbitrary code with SYSTEM privileges.
Apply an update
Disable Remote Desktop Gateway UDP transport
This vulnerability can be mitigated by disabling the UDP transport for Remote Desktop Gateway.
Block access to UDP/3391 at the network level
This vulnerability can be mitigated by blocking access to the Remote Desktop Gateway UDP port, which is UDP/3391 by default.
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Updated: January 14, 2020
No statement is currently available from the vendor regarding this vulnerability.
We are not aware of further vendor information regarding this vulnerability.
Group | Score | Vector
Base | 10 | AV:N/AC:L/Au:N/C:C/I:C/A:C
Temporal | 7.8 | E:POC/RL:OF/RC:C
Environmental | 5.9 | CDP:ND/TD:M/CR:ND/IR:ND/AR:ND
This document was written by Will Dormann.