Advisory
On 12.10.2021 a security relevant correction has been released by SAP SE. The manufacturer resolves an issue within ABAP.
SAP Note 3099011 addresses "[CVE-2021-40495] Denial of Service (DOS) in SAP NetWeaver Application Server for ABAP and ABAP Platform" to prevent denial of service (dos) with a medium risk for exploitation.
A workaround does exist, according to SAP Security Advisory team. It is advisable to implement the correction as monthly patch process, the team suggests.
Missing authority checks are still the most common security defect related to authorizations in custom code. Since SAP uses an explicit authorization model, an authority checks must be coded in order to be executed. If an explicit check is not coded, all users have access. This type of vulnerability not only exists in SAP standard it also exists in customer coding. Check your custom developments for vulnerabilities that pose a risk to your systems. SecurityBridge helps detect code vulnerabilities before they are implemented in production. Denial of Service (DoS) attacks that take a system offline may lead to significant cost for the company, studies quantify the costs in average between 4 and 5 millions dollars. Business continuity requires SAP systems staying online. The CVSS scores or vulnerability descriptions are not enough to represent how a simple bug can lead to a significant loss for companies.
Risk specification
An unauthorized attacker can use the public SICF service /sap/public/bc/abap to reduce the performance of SAP NetWeaver Application Server ABAP and ABAP Platform resulting in a Denial-of-Service Vulnerability.Solution
The denial of service vulnerability (DoS) has been fixed by making the examples not executable from the documentation. Circumstances exist that prevent the timely installation of a patch provided by the manufacturer. In such cases, you may consider applying the suggested workaround as a temporary or compensating mitigation: "Do not activate the ICF-nodes /sap/public/bc/abap/docu and /sap/bc/abap/docu if not necessary. They are necessary only before release 7.55 in development systems where ADT is used. ".
Affected System
The advisory 3099011 describes a problem within an ABAP based systems of a specific version. Affected versions are described below. ABAP software is deployed in various software components and is widely used within the SAP product portfolio.
SAP NetWeaver Application Server (formally known as SAP Web Application Server) is a building block of SAP NetWeaver. It is the foundation for most software products developed by SAP SE. SAP NetWeaver systems exist with Java and/or ABAP stacks. The advisory could be relevant for single and dual-stack ABAP installations.
The advisory is valid for
- 9.8 Multiple Vulnerabilities in SAP Data Services
- 7.5 [CVE-2021-38177] Null Pointer Dereference vulnerability in SAP CommonCryptoLib
- 6.5 [CVE-2020-26826] Unrestricted File Upload vulnerability in SAP NetWeaver Application Server for Java (Process Integration Monitoring)
- 6.5 [CVE-2021-21488] Insecure deserialisation in SAP NetWeaver Knowledge Management
- 6.5 [CVE-2021-27603] Denial of Service (DoS) in SAP NetWeaver AS of ABAP
