Advisory

SAP takes the security of its vast product portfolio very seriously and thus releases security fixes for vulnerabilities reported by external researchers and their customers every second Tuesday of the month.

SAP Note 2870067 was released on 11.02.2020 and deals with "Update 1 to Security Note 2736825 - [CVE-2019-0271] Denial of Service via XML External Entity (XXE) vulnerability in ABAP Server" within ABAP. We advice you to follow the instructions, to resolve external entity tunneling (xxe) with a medium potential for exploitation in component BC-ABA-XML.

According to SAP Security Advisory team a workaround exists. It is advisable to implement the correction as project.

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.

Risk specification

ABAP Server (used in NetWeaver and Suite/ERP) does not sufficiently validate an XML document accepted from an untrusted source.

Solution

The kernel provides profile parameters ixml/dtd_restriction and ixml/xml_expansion_factor to control the behavior of the iXML Toolset. By setting ixml/dtd_restriction value to "expansion", iXML Toolset may handle such error situations gracefully by not stopping the application and delegating the error handling to the application. Alternativly, the consulting team has proposed the following: "Filter engine on IDS/IPS/firewall systems screening for bogus external entity requests.". The suggestion may be considered, as a workaround or compensating mitigation. We recommend installing/applying the correction wherever possible and as soon as possible. Base your decision on whether or not to apply the patch on your companies and systems risk perspective and consider the provided CVSS 6.5 score.

Affected System

The advisory 2870067 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

KRNL64NUC 7.49 ²⁴
KRNL64UC 7.49 ²⁴
KRNL64UC 7.53 ³⁷
KRNL64UC 7.73 ⁵
KERNEL 7.49 ²³
KERNEL 7.53 ³⁷
KERNEL 7.73 ⁵
KERNEL 7.77 ³⁵
KERNEL 7.78
KERNEL 7.79

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 6.5

Component BC-ABA-XML

Patch Day2020-02

Released on2020/02/11

SAP Note 2870067

Workaround Yes

Advisory

Risk specification

Solution

Affected System

Disclaimer

_{Affected system}
ABAP

_CVSS
6.5

_Component
BC-ABA-XML

_{Patch Day}
2020-02

_{Released
on}
2020/02/11

_{SAP Note}
2870067

_Workaround
Yes