Date: 01 August 2003
References: AU-2003.010 ESB-2003.0561 ESB-2003.0579 ESB-2003.0590
Click here for printable version
Click here for PGP verifiable version
-----BEGIN PGP SIGNED MESSAGE-----
===========================================================================
AUSCERT External Security Bulletin Redistribution
ESB-2003.0525 -- CERT Advisory CA-2003-19
Exploitation of Vulnerabilities in Microsoft RPC Interface
01 August 2003
===========================================================================
AusCERT Security Bulletin Summary
---------------------------------
Product: Remote Procedure Call (RPC) Interface
Publisher: CERT/CC
Operating System: Windows NT 4.0
Windows NT 4.0 Terminal Services Edition
Windows 2000
Windows XP
Microsoft Windows Server 2003
Impact: Denial of Service
Administrator Compromise
Access Required: Remote
CVE Names: CAN-2003-0352
Ref: AL-2003.11
AU-2003.010
Comment:
As stated by CERT/CC below, there appears to be a separate
denial-of-service vulnerability in Microsoft's RPC interface
that is also being targeted by current exploit activity. This
vulnerability is believed to be separate and independent from
the RPC vulnerability addressed in AL-2003.11 (MS03-026).
System administrators are again urged to apply the current and
future Microsoft patches relevant to this issue (as they are
made available). Furthermore, administrators should block access
to TCP/UDP ports 135, 139 and 445 at their network borders.
Other ports, such as 80 and 593, may also provide access to RPC
services and these should be filtered as necessary and where
possible. Sites should additionally consider disabling DCOM
services, as described in MS03-026, if they are not explicitly
required.
- --------------------------BEGIN INCLUDED TEXT--------------------
- -----BEGIN PGP SIGNED MESSAGE-----
CERT Advisory CA-2003-19 Exploitation of Vulnerabilities in Microsoft RPC
Interface
Original issue date: July 31, 2003
Last revised: -
Source: CERT/CC
A complete revision history is at the end of this file.
Systems Affected
* Microsoft Windows NT 4.0
* Microsoft Windows NT 4.0 Terminal Services Edition
* Microsoft Windows 2000
* Microsoft Windows XP
* Microsoft Windows Server 2003
Overview
The CERT/CC is receiving reports of widespread scanning and
exploitation of two recently discovered vulnerabilities in Microsoft
Remote Procedure Call (RPC) Interface.
I. Description
Reports to the CERT/CC indicate that intruders are actively scanning
for and exploiting a vulnerability in Microsoft's DCOM RPC interface
as described in VU#568148 and CA-2003-16. Multiple exploits for this
vulnerability have been publicly released, and there is active
development of improved and automated exploit tools for this
vulnerability. Known exploits target TCP port 135 and create a
privileged backdoor command shell on successfully compromised hosts.
Some versions of the exploit use TCP port 4444 for the backdoor, and
other versions use a TCP port number specified by the intruder at
run-time. We have also received reports of scanning activity for
common backdoor ports such as 4444/TCP. In some cases, due to the RPC
service terminating, a compromised system may reboot after the
backdoor is accessed by an intruder.
There appears to be a separate denial-of-service vulnerability in
Microsoft's RPC interface that is also being targeted. Based on
current information, we believe this vulnerability is separate and
independent from the RPC vulnerability addressed in MS03-026. The
CERT/CC is tracking this additional vulnerability as VU#326746 and is
continuing to work to understand the issue and mitigation strategies.
Exploit code for this vulnerability has been publicly released and
also targets TCP port 135.
In both of the attacks described above, a TCP session to port 135 is
used to execute the attack. However, access to TCP ports 139 and 445
may also provide attack vectors and should be considered when applying
mitigation strategies.
II. Impact
A remote attacker could exploit these vulnerabilities to execute
arbitrary code with Local System privileges or to cause a denial of
service condition.
III. Solutions
Apply patches
All users are encouraged to apply the patches referred to in Microsoft
Security Bulletin MS03-026 as soon as possible in order to mitigate
the vulnerability described in VU#568148. These patches are also
available via Microsoft's Windows Update service.
Systems running Windows 2000 may still be vulnerable to at least a
denial of service attack via VU#326746 if their DCOM RPC service is
available via the network. Therefore, sites are encouraged to use the
packet filtering tips below in addition to applying the patches
supplied in MS03-026.
Filter network traffic
Sites are encouraged to block network access to the RPC service at
network borders. This can minimize the potential of denial-of-service
attacks originating from outside the perimeter. The specific services
that should be blocked include
* 135/TCP
* 135/UDP
* 139/TCP
* 139/UDP
* 445/TCP
* 445/UDP
If access cannot be blocked for all external hosts, the CERT/CC
recommends limiting access to only those hosts that require it for
normal operation. As a general rule, the CERT/CC recommends filtering
all types of network traffic that are not required for normal
operation.
Because current exploits for VU#568148 create a backdoor, which is in
some cases 4444/TCP, blocking inbound TCP sessions to ports on which
no legitimate services are provided may limit intruder access to
compromised hosts.
Recovering from a system compromise
If you believe a system under your administrative control has been
compromised, please follow the steps outlined in
Steps for Recovering from a UNIX or NT System Compromise
Reporting
The CERT/CC is tracking activity related to exploitation of the first
vulnerability (VU#568148) as CERT#27479 and the second vulnerability
(VU#326746) as CERT#24523. Relevant artifacts or activity can be sent
to cert@cert.org with the appropriate CERT# in the subject line.
Appendix A. Vendor Information
This appendix contains information provided by vendors. When vendors
report new information, this section is updated and the changes are
noted in the revision history. If a vendor is not listed below, we
have not received their comments.
Microsoft
Please see Microsoft Security Bulletin MS03-026.
Appendix B. References
* CERT/CC Vulnerability Note VU#561284 -
http://www.kb.cert.org/vuls/id/561284
* CERT/CC Vulnerability Note VU#326746 -
http://www.kb.cert.org/vuls/id/326746
* Microsoft Security Bulletin MS03-026 -
http://microsoft.com/technet/security/bulletin/MS03-026.asp
* Microsoft Knowledge Base article 823980 -
http://support.microsoft.com?kbid=823980
______________________________________________________________________
Authors: Chad Dougherty and Kevin Houle
______________________________________________________________________
This document is available from:
http://www.cert.org/advisories/CA-2003-19.html
______________________________________________________________________
CERT/CC Contact Information
Email: cert@cert.org
Phone: +1 412-268-7090 (24-hour hotline)
Fax: +1 412-268-6989
Postal address:
CERT Coordination Center
Software Engineering Institute
Carnegie Mellon University
Pittsburgh PA 15213-3890
U.S.A.
CERT/CC personnel answer the hotline 08:00-17:00 EST(GMT-5) /
EDT(GMT-4) Monday through Friday; they are on call for emergencies
during other hours, on U.S. holidays, and on weekends.
Using encryption
We strongly urge you to encrypt sensitive information sent by email.
Our public PGP key is available from
http://www.cert.org/CERT_PGP.key
If you prefer to use DES, please call the CERT hotline for more
information.
Getting security information
CERT publications and other security information are available from
our web site
http://www.cert.org/
To subscribe to the CERT mailing list for advisories and bulletins,
send email to majordomo@cert.org. Please include in the body of your
message
subscribe cert-advisory
* "CERT" and "CERT Coordination Center" are registered in the U.S.
Patent and Trademark Office.
______________________________________________________________________
NO WARRANTY
Any material furnished by Carnegie Mellon University and the Software
Engineering Institute is furnished on an "as is" basis. Carnegie
Mellon University makes no warranties of any kind, either expressed or
implied as to any matter including, but not limited to, warranty of
fitness for a particular purpose or merchantability, exclusivity or
results obtained from use of the material. Carnegie Mellon University
does not make any warranty of any kind with respect to freedom from
patent, trademark, or copyright infringement.
______________________________________________________________________
Conditions for use, disclaimers, and sponsorship information
Copyright 2003 Carnegie Mellon University.
Revision History
July 31, 2003: Initial release
- -----BEGIN PGP SIGNATURE-----
Version: PGP 6.5.8
iQCVAwUBPyl3xGjtSoHZUTs5AQE8gAQAqCNAwHihfJzIH8DJDaWxGqacDZYAzGjh
30rPq9AM1/0KkvsdfHb6MC/b+ktCZBrMvXew1e+WGOoE0McZ+IuB9t2DIGsFCBuo
ltqDw8v08FLM+7zsAM0DooEZLdNpkqdiKhKvooyJ6LGrj5Nb5inW5joITSBn9MMY
YSIQfaGqABU=
=m+s3
- -----END PGP SIGNATURE-----
- --------------------------END INCLUDED TEXT--------------------
You have received this e-mail bulletin as a result of your organisation's
registration with AusCERT. The mailing list you are subscribed to is
maintained within your organisation, so if you do not wish to continue
receiving these bulletins you should contact your local IT manager. If
you do not know who that is, please send an email to auscert@auscert.org.au
and we will forward your request to the appropriate person.
This security bulletin is provided as a service to AusCERT's members. As
AusCERT did not write the document quoted above, AusCERT has had no control
over its content. The decision to follow or act on information or advice
contained in this security bulletin is the responsibility of each user or
organisation, and should be considered in accordance with your organisation's
site policies and procedures. AusCERT takes no responsibility for consequences
which may arise from following or acting on information or advice contained in
this security bulletin.
NOTE: This is only the original release of the security bulletin. It may
not be updated when updates to the original are made. If downloading at
a later date, it is recommended that the bulletin is retrieved directly
from the author's website to ensure that the information is still current.
Contact information for the authors of the original document is included
in the Security Bulletin above. If you have any questions or need further
information, please contact them directly.
Previous advisories and external security bulletins can be retrieved from:
http://www.auscert.org.au/render.html?cid=1980
If you believe that your computer system has been compromised or attacked in
any way, we encourage you to let us know by completing the secure National IT
Incident Reporting Form at:
http://www.auscert.org.au/render.html?it=3192
Internet Email: auscert@auscert.org.au
Facsimile: (07) 3365 7031
Telephone: (07) 3365 4417 (International: +61 7 3365 4417)
AusCERT personnel answer during Queensland business
hours which are GMT+10:00 (AEST). On call after hours
for member emergencies only.
-----BEGIN PGP SIGNATURE-----
Comment: http://www.auscert.org.au/render.html?it=1967
iQCVAwUBPymgvSh9+71yA2DNAQEftgP9HQmmr3T4PvkWzy0V25jhawUo0kmV0SBj
ceZF3nh/5lrf8Wa4OZ9BWXQCmzf24ll0tS60JjeWa3bEFtj2o4Xw1jZEXy5ta4LP
7apd7/lNTjJ4qmMSNgpePyz1pYgmcxX0w6pYpW6qeII63+JlUNLthMXVtgbbxq6O
JsXb/UwrWy0=
=9tVB
-----END PGP SIGNATURE-----
|