[ERPSCAN-17-030] SAP Hostcontrol remote DOS

Application: SAP NetWeaver AS Java
Versions Affected: SAP NetWeaver AS Java 7.0 – 7.5
Vendor URL: SAP
Bug: DoS
Reported: 01.11.2016
Vendor response: 02.11.2016
Date of Public Advisory: 13.06.2017
Reference: SAP Security Note 2389181
Authors: Mathieu Geli (ERPScan)

VULNERABILITY INFORMATION

Class: DoS
Impact: Unavailability of resources
Remotely Exploitable: Yes
Locally Exploitable: No

CVSS Information

CVSS v3 Base Score: 7.5 / 10
CVSS v3 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 AvailabilityHigh (H)

Description

A malicious user can send specific web requests on the SAP HostControl port to cause the service termination.

Business risk

An attacker can exploit a Denial of Service vulnerability to terminate a process of a vulnerable component. For this time, nobody can use this service, this fact negatively affects business processes, system downtime, and business reputation as a result.

VULNERABLE PACKAGES

HDB 1.00 1.00
HDB 2.00 2.00
KRNL32NUC 7.22
KRNL32NUC 7.22EXT
KRNL32UC 7.22
KRNL32UC 7.22EXT
KRNL64NUC 7.42
KRNL64NUC 7.22
KRNL64NUC 7.22EXT
KRNL64NUC 7.45
KRNL64NUC 7.48
KRNL64NUC 7.49
KRNL64NUC 7.50
KRNL64NUC 7.51
KRNL64UC 8.04
KRNL64UC 7.42
KRNL64UC 7.22
KRNL64UC 7.22EXT
KRNL64UC 7.45
KRNL64UC 7.48

SOLUTIONS AND WORKAROUNDS

To correct this vulnerability, install SAP Security Note 2389181

TECHNICAL DESCRIPTION

A malicious user can send specific web requests to the SAP HostControl service that will ask for authentication.

When providing wrong username/password the subsequent authenticating process (sapuxuserchk) waits for some seconds.

If the attacker sents a lot of requests (nearly 2000), the sapstartsrv will exhaust its stack space and daemon will be terminated with a SIGSEV signal.

The daemon will not be restarted.