Windows Services for UNIX contain a vulnerability that could allow a local attacker to gain escalated privileges. Updates are available.
Description
Windows Services for UNIX versions 3.0 and 3.5 contain a vulnerability that could allow a local attacker to gain elevated privileges.
The vulnerability exists due to improper handling of setuid commands. A local attacker could exploit this vulnerability by running a setuid binary application as part of Windows Services for UNIX. Such a command could allow the attacker to run applications or make changes to files with elevated privileges.
Microsoft has confirmed this vulnerability in a security bulletin and released software updates.
Warning Indicators
Windows Services for UNIX versions 3.0 and 3.5 and Subsystem for UNIX-based applications are vulnerable when running on the following systems:
Microsoft Windows 2000 SP4 and prior Microsoft Windows XP SP2 and prior Microsoft Windows Server 2003 SP2 and prior Microsoft Windows Server 2003 x64 SP2 and prior Microsoft Windows Vista Microsoft Windows Vista x64 Edition
IntelliShield Analysis
To exploit this vulnerability, an attacker must log on locally to an affected system and run a command. Systems most at risk are workstations and terminal servers that have Windows Services for UNIX installed and allow multiple-user access.
This vulnerability is likely due to a failure to properly handle root-owned files that have the setuid bit set. Because such files are executed with the privileges of the file owner, an attacker could take complete control of the affected system.
Subsystem for UNIX-based applications on Windows Vista and Windows Server 2003 contains components of the Windows Services for UNIX.
Vendor Announcements
Microsoft has released a security bulletin at the following link: MS07-053
Impact
A local attacker could exploit this vulnerability to gain escalated privileges on an affected system. An exploit may result in a complete system compromise.
Technical Information
An attacker with local account access could exploit this vulnerability. No further authentication is required.
This vulnerability exists because Windows Services for UNIX does not properly handle certain setuid binaries that are included with the package. Windows Server and Windows Vista do not restrict the use of setuid binary files. A local attacker could exploit this vulnerability to execute certain commands with elevated privileges, allowing the attacker to execute arbitrary commands or modify critical files with elevated privileges.
Safeguards
Administrators are advised to apply the available updates.
Administrators are advised to grant system access only to trusted users.
Administrators may consider uninstalling Windows Services for UNIX.
Patches/Software
Microsoft has released updated software at the following links:
Business Base | Business x64 Edition Base | Enterprise Base | Enterprise x64 Edition Base | Home Basic Base | Home Basic x64 Edition Base | Home Premium Base | Home Premium x64 Edition Base | Ultimate Base | Ultimate x64 Edition Base
Microsoft, Inc.
Windows XP
Home Edition Base, SP1, SP2 | Professional Edition Base, SP1, SP2
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