Advisory

On 09.02.2021 a security relevant correction has been released by SAP SE. The manufacturer resolves an issue within ABAP.

SAP Note 2974582 addresses "[CVE-2021-21478] Reverse Tabnabbing vulnerability in SAP NetWeaver Application Server ABAP (Applications based on Web Dynpro ABAP)" to prevent reverse tabnabbing with a medium risk for exploitation.

A workaround does not 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. Reverse tabnabbing is an attack where a page linked from the target page is able to rewrite that page, for example to replace it with a phishing site. The following figure shows a brief illustration:

Reverse Tabnabbing Overview — Source: OWASP.org

While the user was originally on the correct page there is a high risk they will not notice that it has been changed to a phishing site.

Risk specification

SAP Web Dynpro ABAP allows an unauthenticated remote attacker to redirect users to a malicious site due to insufficient reverse tabnabbing URL validation.

Solution

A default out-of-the-box protection is applied for all Business Server Pages applications.

Affected System

The advisory 2974582 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

Releated advisories

Disclaimer

SecurityBridge takes the security of SAP products very seriously. We very much encourage the responsible disclosure of security vulnerabilities. If you have detected a vulnerability concerning one of the SAP software products – either in the latest or in a former product version follow the guidelines and processes in accordance with the SAP portal page “Report a Security Vulnerability to SAP”.

The advisories found within the SecurityBridge advisory are generated and continuously enriched by our Team at SecurityBridge and affiliated security consultants, partners, customers of the SecurityBridge Platform, SAP support, and advisory groups.

We do not disclose zero-day vulnerabilities unless a security patch has been made available to the public. In such case, the platform only provides details on which version or signature updates are available within the SecurityBridge platform in order to monitor or measure the vulnerability.

In accordance with SAP guidelines, SecurityBridge only discloses issues where the fixing security note has been released. The vulnerability platform makes no references to available exploits or Proof of Concepts (PoC). Advisories and vulnerabilities will always mention the fixing security note or hints to the corresponding SAP documentation.

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Notifications

Affected system ABAP

CVSS 4.7

Component BC-WD-ABA

Patch Day2021-02

Released on2021/02/09

SAP Note 2974582

Workaround No

Advisory

Risk specification

Solution

Affected System

Disclaimer

_{Affected system}
ABAP

_CVSS
4.7

_Component
BC-WD-ABA

_{Patch Day}
2021-02

_{Released
on}
2021/02/09

_{SAP Note}
2974582

_Workaround
No