Vulnerability Alert

Microsoft Windows Task Scheduler Privilege Escalation Vulnerability

 
Threat Type:CWE-264: Permissions, Privileges, and Access Control
IntelliShield ID:21657
Version:3
First Published:2010 October 25 14:13 GMT
Last Published:2010 December 14 18:55 GMT
Port: Not available
BugTraq ID:44357
Urgency:Unlikely Use
Credibility:Confirmed
Severity:Moderate Damage
CVSS Base:6.8 CVSS Calculator
CVSS Version 2.0
CVSS Temporal:5.6
 
Version Summary:

Microsoft has released a security bulletin and software updates to address the Microsoft Windows Task Scheduler privilege escalation vulnerability.

 
 
Description

Microsoft Windows contains a vulnerability that could allow a local attacker to gain elevated privileges.

The vulnerability exists due to insufficient validation performed by the Task Scheduler service on XML schema files.  A local attacker could exploit this vulnerability by submitting malicious requests to the system.  If successful, the attacker could execute arbitrary code on the system with SYSTEM privileges.

Functional code that exploits this vulnerability is publicly available.

Microsoft confirmed the vulnerability in a security bulletin and released software updates.

 
Warning Indicators

The following products are vulnerable:

  • Windows Vista SP2 and prior
  • Windows Vista x64 Edition SP2 and prior
  • Windows Server 2008 for 32-bit Systems SP2 and prior
  • Windows Server 2008 for x64-based Systems SP2 and prior
  • Windows Server 2008 Itanium-based Edition SP2 and prior
  • Windows 7 for 32-bit Systems
  • Windows 7 for x64-based Systems
  • Windows Server 2008 R2 for x64-based Systems
  • Windows Server 2008 R2 for Itanium-based Systems
 
IntelliShield Analysis

The attacker must possess credentials sufficient to authenticate to the system prior to exploitation.  The access requirement reduces the likelihood of a possible attack.

Reports indicate the vulnerability is being actively exploited in the wild by the W32/Stuxnet-B malicious software documented in IntelliShield Alert 20915.  The malicious software exploits a privilege escalation vulnerability that is already present on the system because of another vulnerability or because the attacker has used social engineering techniques to persuade a user to open a malicious executable file.

By exploiting the privilege escalation vulnerability, the malicious software could take complete control over the system.  The behavior is most useful on systems such as Windows Vista or Windows 7 where users typically hold only limited privileges, limiting the privileges of any malicious code present on the system.

 
Vendor Announcements

Microsoft has released a security bulletin at the following link: MS10-092

 
Impact

A local attacker could exploit this vulnerability to execute arbitrary code on the system with SYSTEM privileges, possibly resulting in a complete system compromise.

 
Technical Information

The vulnerability is due to insufficient validation of XML schema files processed by the Task Scheduler service.  The Task Scheduler does not properly check fields in unspecified XML schema files that could be accessed and manipulated via the Component Object Model (COM) interface.

A local attacker could exploit this vulnerability by submitting malicious requests to the COM interface, allowing the attacker to manipulate a valid XML schema file.  The processing of the modified XML schema files by the Task Scheduler could allow the attacker to load tasks in the Task Scheduler that would run with SYSTEM privileges.

 
Safeguards

Administrators are advised to apply the available software updates.

Administrators are advised to allow only trusted users to access local systems.

Administrators are advised to implement physical security for production servers.

Administrators are advised to monitor affected systems.

 
Patches/Software

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.

 
Alert History
 

Version 2, November 22, 2010, 3:22 PM: Functional code that exploits the Microsoft Windows Task Scheduler privilege escalation vulnerability is publicly available.

Version 1, October 25, 2010, 9:13 AM: Multiple Microsoft Windows operating systems contain a vulnerability that could allow an unprivileged, local attacker to gain elevated privileges.  Updates are not available.



Product Sets
 
The security vulnerability applies to the following combinations of products.

Primary Products:
Microsoft, Inc.Windows 7 for 32-bit systems Base | for x64-based systems Base
Microsoft, Inc.Windows Server 2008 Datacenter Edition Base, SP1, SP2 | Datacenter Edition, 64-bit Base, SP1, SP2 | Itanium-Based Systems Edition Base, SP1, SP2 | Enterprise Edition Base, SP1, SP2 | Enterprise Edition, 64-bit Base, SP1, SP2 | Essential Business Server Standard Base, SP1, SP2 | Essential Business Server Premium Base, SP1, SP2 | Essential Business Server Premium, 64-bit Base, SP1, SP2 | Standard Edition Base, SP1, SP2 | Standard Edition, 64-bit Base, SP1, SP2 | Web Server Base, SP1, SP2 | Web Server, 64-bit Base, SP1, SP2
Microsoft, Inc.Windows Server 2008 R2 x64-Based Systems Edition Base | Itanium-Based Systems Edition Base
Microsoft, Inc.Windows Vista Home Basic Base, SP1, SP2 | Home Premium Base, SP1, SP2 | Business Base, SP1, SP2 | Enterprise Base, SP1, SP2 | Ultimate Base, SP1, SP2 | Home Basic x64 Edition Base, SP1, SP2 | Home Premium x64 Edition Base, SP1, SP2 | Business x64 Edition Base, SP1, SP2 | Enterprise x64 Edition Base, SP1, SP2 | Ultimate x64 Edition Base, SP1, SP2

Associated Products:
N/A




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