[THIN] FYI: Microsoft Windows Remote Desktop Protocol service input validation vulnerability
- From: "Jim Kenzig Kenzig.com" <jkenzig@xxxxxxxxx>
- To: thin@xxxxxxxxxxxxx
- Date: Wed, 10 Aug 2005 06:19:04 -0700 (PDT)
From US Cert
JK
Vulnerability Note VU#490628Microsoft Windows Remote Desktop Protocol service
input validation vulnerabilityOverview
http://www.kb.cert.org/vuls/id/490628
An input validation error in the Microsoft Remote Desktop Protocol (RDP)
service may allow a remote attacker to cause a denial-of-service condition.
I. DescriptionMicrosoft describes the Remote Desktop Protocol (RDP) as follows.
RDP is based on, and is an extension of, the T.120 protocol family standards.
It is a multichannel-capable protocol that allows for separate virtual channels
for carrying device communication and presentation data from the server, as
well as encrypted client mouse and keyboard data.
The Microsoft RDP service contains an input validation error that can be
exploited to cause a denial-of-service condition. A remote attacker may be able
to exploit this vulnerability by sending a system running the RDP service a
specially crafted message on port 3389/tcp. Note note that the Microsoft
Firewall will allow RDP traffic to enter a system by default.
The RDP service is not enabled by default on Microsoft Windows, but may be
enabled if the following components are installed and running:
Microsoft Terminal Services
Microsoft Remote Desktop
Microsoft Remote Assistance
Windows Small Business Server 2003 Remote Web Workplace
Note that exploit code for this vulnerability is publicly available. For more
information regarding this issue, please refer to MS05-041.
II. ImpactThis vulnerability allows unauthorized, remote attackers to crash a
system running the RDP service resulting in a denial-of-service condition. III.
SolutionApply An Update
Microsoft has addressed this issue in Microsoft Security Bulletin MS05-041.
Microsoft recommends the following workarounds. While these workarounds will
not correct the underlying vulnerability, they help block known attack vectors.
Disable Terminal Services, Remote Desktop, Remote Assistance, and Windows Small
Business Server 2003 Remote Web Workplace feature.
Disabling Terminal Services, Remote Desktop, Remote Assistance, and Windows
Small Business Server 2003 Remote Web Workplace may reduce the risk of
exploitation.
Block port 3389/tcp at the perimeter:
Port 3389/tcp is the port used by RDP. Blocking access to this port from
untrusted sources may reduce the risk of exploitation. It may also be necessary
to block port 4125/tcp which is used by Windows Small Business Server 2003 for
RDP connections. Systems AffectedVendorStatusDate UpdatedMicrosoft
CorporationVulnerable9-Aug-2005References
http://www.microsoft.com/technet/security/advisory/904797.mspx
http://www.microsoft.com/windowsxp/using/helpandsupport/rafaq-technical.mspx
http://www.microsoft.com/resources/documentation/Windows/XP/all/reskit/en-us/prmb_tol_drft.asp
http://security-protocols.com/modules.php?name=News&file=article&sid=2852
http://secunia.com/advisories/16071/
http://securitytracker.com/alerts/2005/Jul/1014498.html
http://www.microsoft.com/technet/security/bulletin/MS05-041.mspx Credit
This vulnerability was reported in Microsoft Security Bulletin MS05-041.
Microsoft credits Tom Ferris of Security Protocols for providing information
regarding this vulnerability.
This document was written by Jeff Gennari and Will Dorman Other InformationDate
Public07/14/2005Date First Published08/09/2005 03:58:15 PMDate Last
Updated08/10/2005CERT Advisory CVE NameCAN-2005-1218Metric16.12Document
Revision62
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