The IIS 10.0 websites MaxConnections setting must be configured to limit the number of allowed simultaneous session requests.

Documentable No

Rule ID SV-218826r960735_rule

CCI References

CCI-000054

Discussion

Resource exhaustion can occur when an unlimited number of concurrent requests are allowed on a website, facilitating a Denial of Service (DoS) attack. Mitigating this kind of attack will include limiting the number of concurrent HTTP/HTTPS requests per IP address and may include, where feasible, limiting parameter values associated with keepalive (i.e., a parameter used to limit the amount of time a connection may be inactive).

Check Procedure

Access the IIS 10.0 IIS Manager.

Click the IIS 10.0 server.

Select "Configuration Editor" under the "Management" section.

From the "Section:" drop-down list at the top of the configuration editor, locate "system.applicationHost/sites".

Expand "siteDefaults".
Expand "limits".

Review the results and verify the value is greater than zero for the "maxconnections" parameter.

If the maxconnections parameter is set to zero, this is a finding.

Fix Action

Access the IIS 10.0 IIS Manager.

Click the IIS 10.0 server.

Select "Configuration Editor" under the "Management" section.

From the "Section:" drop-down list at the top of the configuration editor, locate "system.applicationHost/sites".

Expand "siteDefaults".
Expand "limits".

Set the "maxconnections" parameter to a value greater than zero.