Mappings to unused and vulnerable scripts on the IIS 8.5 website must be removed.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-76799	IISW-SI-000215	SV-91495r2_rule		Medium

Description
IIS 8.5 will either allow or deny script execution based on file extension. The ability to control script execution is controlled through two features with IIS 8.5, “Request Filtering” and "Handler Mappings". For "Request Filtering", the ISSO must document and approve all allowable file extensions the website allows (white list) and denies (black list) by the website. The white list and black list will be compared to the "Request Filtering" in IIS 8. "Request Filtering" at the site level take precedence over "Request Filtering" at the server level.

Description

IIS 8.5 will either allow or deny script execution based on file extension. The ability to control script execution is controlled through two features with IIS 8.5, “Request Filtering” and "Handler Mappings". For "Request Filtering", the ISSO must document and approve all allowable file extensions the website allows (white list) and denies (black list) by the website. The white list and black list will be compared to the "Request Filtering" in IIS 8. "Request Filtering" at the site level take precedence over "Request Filtering" at the server level.

STIG	Date
IIS 8.5 Site Security Technical Implementation Guide	2019-10-01

Details

Check Text ( C-76455r3_chk )
For "Request Filtering", the ISSO must document and approve all allowable scripts the website allows (white list) and denies (black list) by the website. The white list and black list will be compared to the "Request Filtering" in IIS 8.5. "Request Filtering" at the site level take precedence over "Request Filtering" at the server level. Open the IIS 8.5 Manager. Click the site name under review. Double-click Request Filtering->File Name Extensions Tab. If any script file extensions from the black list are not denied, this is a finding.

Check Text ( C-76455r3_chk )

For "Request Filtering", the ISSO must document and approve all allowable scripts the website allows (white list) and denies (black list) by the website. The white list and black list will be compared to the "Request Filtering" in IIS 8.5. "Request Filtering" at the site level take precedence over "Request Filtering" at the server level.

Open the IIS 8.5 Manager.

Click the site name under review.

Double-click Request Filtering->File Name Extensions Tab.

If any script file extensions from the black list are not denied, this is a finding.

Fix Text (F-83495r2_fix)
Open the IIS 8.5 Manager. Click the site name under review. Double-click Request Filtering->File Name Extensions Tab->Deny File Name Extension. Add any script file extensions listed on the black list that are not listed. Select "Apply" from the "Actions" pane.