Advisory

A note with CVSS 8.8 for component KM-KW-HTA was released by SAP on 14.12.2021. The correction/advisory 3102769 was described with "[CVE-2021-42063] Cross-Site Scripting (XSS) vulnerability in SAP Knowledge Warehouse" and affects the system type Java.

A workaround exists, according to SAP Security Advisory team. It is advisable to implement the correction as monthly patch process.

The vulnerability addressed is Cross-Site Scripting (XSS) within Java.

Cross-site scripting (XSS) is the name of a class of security vulnerabilities that can occur in web-based applications. XSS combines all vulnerabilities that allow an attacker to inject HTML Markup and/or JavaScript into the front end of the affected web application.

XSS attacks can occur whenever the application dynamically creates its HTML/JavaScript/CSS content, which is passed to the user's web browser, and attacker-controlled values are used in this process. If these values are included in the generated code without proper validation and encoding, the attacker is able to include arbitrary coding snippets into the application's front end. The code is then rendered by the victim's web browser and interpreted in the victim's current authentication context.

Risk specification

Solution

The user input is now properly encoded to prevent a successful XSS attack.  Although an alternative solution exists, it is advisable to apply the correction! This is the workaround, which was suggested by the SAP security experts: "Option 1: You may disable the vulnerable application following the documentation in "Config Tool Adding Filters - SAP Help Portal" (https://help.sap.com/viewer/0c333adb55cd4dbf8e92a5175703224c/7.5.19/en-US/47b1a4e5ac671599e10000000a42189c.html). 'Component Name Mask' parameter should be set as tc~km_tc*, 'Vendor Mask' Parameter - sap.com. Option 2: In case the requests are routed via SAP Web Dispatcher you may add a rewrite rule to SAP Web Dispatcher to prevent from redirects. Add the following rewrite rule to your Web Dispatcher configuration. RegIForbiddenUrl ^/path/of/java/app.* -If there is an existing icm/HTTP/mod_<x> = PREFIX=/, FILE=<...> in your setup: Add the new rule (above) to your existing rule file. Restart the Web Dispatcher or reload the file using the Web Administration UI. Otherwise: Create a new file on the file system (for example in the profile directory) and enter the role above in that file.Add a new parameter icm/HTTP/mod_0 = PREFIX=/, FILE=<your created file>. Do not forget to restart the Web Dispatcher. ".

Affected System

SAP Netweaver Application Server Java is part of the SAP NetWeaver Application Platform. It provides the complete infrastructure for deploying and running Java applications.

• The AS Java Home: SAP Netweaver Application Server Java wiki
• A dedicated SAP NetWeaver 7.40 Application Server for Java Security Guide   exists.

The advisory is valid for

• KM-KW_JIKS 7.30
• KM-KW_JIKS 7.31
• KM-KW_JIKS 7.40
• KM-KW_JIKS 7.50