Detections
Analytics

1.8.6 Ensure XDMCP is not enabled

Information

X Display Manager Control Protocol (XDMCP) is designed to provide authenticated access to display management services for remote displays

XDMCP is inherently insecure.

 - XDMCP is not a ciphered protocol. This may allow an attacker to capture keystrokes entered by a user
 - XDMCP is vulnerable to man-in-the-middle attacks. This may allow an attacker to steal the credentials of legitimate users by impersonating the XDMCP server.

Solution

Edit the file /etc/gdm/custom.conf and remove the line from the [xdmcp] block:

Enable=true

Example:

# GDM configuration storage

[daemon]
WaylandEnable=false

[security]

[xdmcp]

[chooser]

[debug]
# Uncomment the line below to turn on debugging
#Enable=true

See Also

https://workbench.cisecurity.org/benchmarks/23597

Item Details

Category: CONFIGURATION MANAGEMENT

References: 800-53|CM-6, 800-53|CM-7, CSCv7|9.2

Plugin: Unix

Control ID: 7273dc8b425e726405f5fcf4b8ead52eece3a503a4b14f4f15d79c8326dfc983