Microsoft has released a security bulletin and software updates to address the Microsoft SharePoint Help.aspx cross-site scripting vulnerability.
Microsoft Windows SharePoint Services SP2 and prior contain a cross-site scripting vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary HTML or script code in a user's browser.
The vulnerability is due to improper validation of user-supplied input to certain web pages that could permit cross-site scripting attacks. An attacker could exploit the vulnerability to inject arbitrary HTML or script code into the user's browser that could allow the attacker to spoof content, disclose potentially sensitive information, or take actions as the user on the site.
Proof-of-concept code that exploits this vulnerability is publicly available.
Microsoft has confirmed this vulnerability and released software updates.
Microsoft Windows SharePoint Services 3.0 SP2 and prior are vulnerable.
To exploit the vulnerability, an attacker must employ social engineering tactics, convincing the targeted user to follow a link to a malicious website. An exploit could allow the attacker to conduct cross-site scripting attacks against the user that could lead to information disclosure or other attacks against the user.
Microsoft has released a security bulletin at the following link: MS10-039
Microsoft has released a security advisory at the following link: 983438
An unauthenticated, remote attacker could exploit this vulnerability to conduct cross-site scripting attacks. An exploit could allow the attacker to obtain sensitive information about the user, such as authentication cookies. The attacker could also spoof content or take actions on the site as the user.
This vulnerability is in the /LAYOUTS/Help.aspx source file because of insufficient validation of user-supplied input to the cid0 variable.
An unauthenticated, remote attacker could exploit the vulnerability by convincing a user to follow a link that is designed to pass malicious HTML or script code to the unchecked variable. If the user follows the link, the URL may cause the vulnerable application to return unsanitized input to the user's browser, where the input may execute in the security context of the affected site. If successful, the attacker could access sensitive browser-based information.
Administrators are advised to apply the available software updates.
Administrators are advised to allow only trusted users to have network access.
Administrators may consider restricting access to the Help.aspx script.
Administrators are advised to use an unprivileged account for routine activities.
Users should verify that unsolicited links are safe to follow.
Administrators are advised to monitor affected systems.
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.
Version 2, April 30, 2010, 11:03 AM: Microsoft has released a security advisory to address the Microsoft SharePoint server 2007 cross-site scripting vulnerability.
Version 1, April 29, 2010, 1:00 PM: Microsoft SharePoint Server 2007 contains a cross-site scripting vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary HTML or script code in a user's browser. Updates are not available.
The security vulnerability applies to the following combinations of products.
Windows SharePoint Services
3.0 Base, SP1, SP2
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