Microsoft Windows contains a vulnerability in the Remote Desktop Connection ActiveX control that could allow an unauthenticated, remote attacker to gain complete control over an affected system.
The vulnerability exists because of a heap overflow vulnerability in the Remote Desktop Connection ActiveX control. If an attacker can convince a user to connect to a malicious website, the attacker can execute arbitrary code on the client machine with the privileges of the user.
Microsoft has acknowledged this vulnerability in a security bulletin and has released software updates that correct it.
Indicators of Compromise
The following Microsoft systems are affected:
Windows XP SP2 and SP3
Windows Vista SP1 and SP2
Windows Vista x64 Edition SP1 and SP2
Windows Server 2008 for 32-bit Systems SP2 and prior
Windows Server 2008 for x64-based Systems SP2 and prior
Windows Server 2008 for Itanium-based Systems SP2 and prior
The following systems are affected if the Remote Desktop Protocol (RDP) Connection out-of-band download has been installed on the system:
Windows 2000 SP4 and prior, when using RDP Connection 6.0 or 6.1
Windows XP SP2 and prior, when using RDP Connection 6.0 or 6.1
Windows Server 2003 SP2 and prior when using RDP Connection 6.0 or 6.1
Windows Vista SP1 when using RDP Connection 6.1
The vulnerability exists because the Remote Desktop Connection ActiveX control on affected systems does not properly handle memory when it receives parameters from a malicious website. An attacker can use a malicious site to execute arbitrary code with the privileges of the user's account.
The victim may be enticed to follow a link to a malicious page through an e-mail message, instant messenger conversation, social networking site, or other web-enabled medium.
This vulnerability does not affect Remote Desktop Connection server code, only client code.
This vulnerability requires an attacker to convince a user to connect to a malicious system. An attacker might exploit this vulnerability by convincing an administrator that the malicious system is instead a system that requires remote assistance via the web, employing a man-in-the-middle attack between the user and a legitimate system, or using a web-based attack through the Remote Desktop ActiveX control. It is also possible for an attacker to use SQL injection or other "drive-by" attack methods to include malicious code on sites that users trust.
Microsoft has corrected this vulnerability by improving the handling of unexpected parameters by the methods in the ActiveX control.
Administrators are advised to apply the appropriate updates.
Users are advised not to open e-mail messages from suspicious or unrecognized sources. If users cannot verify that links or attachments included in e-mail messages are safe, they are advised not to open them.
Administrators are advised to implement an intrusion prevention system (IPS) or intrusion detection system (IDS) to help detect and prevent attacks that attempt to exploit this vulnerability.
Administrators may consider configuring Internet Explorer to prompt users before running Active Scripting or ActiveX controls by setting the Internet and Local Intranet security zone settings to High. Alternately, administrators could disable Active Scripting and ActiveX controls in these security zones.
Administrators may consider using the Microsoft Baseline Security Analyzer (MBSA) scan tool to identify common security misconfigurations and missing security updates on system endpoints.
Microsoft has released a security bulletin at the following link: MS09-044
Microsoft customers can obtain updates directly by using the links in the security bulletin. These updates are also distributed by Windows automatic update features and available on the Windows Update website. Microsoft Windows Server Update Services (WSUS), Systems Management Server, and System Center Configuration Manager can assist administrators in deploying software updates.
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