[ERPSCAN-17-014] SAP Netweaver Java deserialization of untrusted user value in metadatauploader

Application: SAP NetWeaver
Versions Affected: SAP NetWeaver 7400.12.21.30308
Vendor URL: SAP
Bugs: DoS
Reported: 01.11.2016
Vendor response: 02.11.2016
Date of Public Advisory: 14.03.2017
Reference: SAP Security Note 2399804
Author: Vahagn Vardanyan(ERPScan) & Mathieu Geli (ERPScan)

VULNERABILITY INFORMATION

Class: DoS
Impact: Denial of Service
Remotely Exploitable: yes
Locally Exploitable: no
CVE: CVE-2017-9844

CVSS Information

CVSS Base Score v3: 7.5 / 10
CVSS Base Vector:

AV: Attack Vector (Related exploit range) Network (N)
AC: Attack Complexity (Required attack complexity) Low (L)
PR: Privileges Required (Level of privileges needed to exploit) None (N)
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 None (N)
I: Impact to Integrity None (N)
A: Impact to Availability High (H)

Description

An attacker can use a special HTTP request in order to force the server to deserialize evil objects and get at least DoS and at best RCE.

Business risk

An attacker can use a Denial of Service vulnerability for terminating the process of a vulnerable component. For this time nobody can use this service. This fact negatively influences business processes, system downtime, and business reputation as a result.

VULNERABLE PACKAGES

SAP NetWeaver 7400.12.21.30308

Other versions are probably affected too, but they were not checked.

SOLUTIONS AND WORKAROUNDS

To correct this vulnerability, install SAP Security Note 2399804

TECHNICAL DESCRIPTION

Proof of Concept

If we send the serialized data to the SAP server, we use this request: curl -v -XPOST http://:/developmentserver/metadatauploader?CONTENTTYPE=MODEL&CLIENT=admin --data-binary @PoC.zip

We can see opened calc.exe