From xforce@ISS.NET Thu Oct 23 11:41:17 1997 Date: Wed, 22 Oct 1997 17:22:31 -0400 From: X-Force To: BUGTRAQ@NETSPACE.ORG Subject: ISS Security Alert -----BEGIN PGP SIGNED MESSAGE----- ISS Security Alert October 21, 1997 Scheduler/Winlogin Keys have Incorrect Permissions This advisory describes two similar configuration problems in the Windows NT Registry key permissions. These vulnerabilities can allow users with Server Operator privilege to increase their access level to Administrator. Problem 1: Scheduler Key Has Incorrect Permissions Affects: Windows NT Description: The HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Schedule key controls the schedule service. Server Operators have permission to write to this registry tree, which would allow them to manually schedule jobs to be run by the schedule service, which normally executes under the system user context. This can be used to raise the Server Operator's access level to Administrator. Risk: Medium Solution: Local Machine (GUI): From the Start menu, choose 'Run.' Type 'regedt32' and click 'OK.' This opens the Registry Editor. Through the Security menu, remove write access to the Schedule key for Server Operators. Problem 2: Winlogon Key Has Incorrect Permissions Affects: Windows NT Description: The HKEY_LOCAL_MACHINE\Software\Microsoft\WindowsNT\CurrentVersion\Winlogon key has two values which can be used to cause a process to execute upon either system bootup, or when a user logs on. The programs pointed to by the System value run under the system user context after boot, and could be used to change a user's rights or access level. The UserInit value runs applications when a user logs in. The default settings for this key allow Server Operators to write these values, either of which could be used to raise a System Operator's access level to Administrator. Risk: Medium Solution: Local Machine (GUI): From the Start menu, choose 'Run.' Type 'regedt32' and click 'OK.' This opens the Registry Editor. Through the Security menu, remove write access to the Winlogon key for Server Operators. ========================================================================= Caution: Care must be taken when using the Registry Editor. If incorrect values are entered, the system may become inoperable. Should a mistake be made when editing the registry values, the registry state can be restored to the state at the last time the system booted up. For more information, see the Windows NT Help under the "Registry" section. ========================================================================= Acknowledgments: This problem was identified by David LeBlanc of ISS (dleblanc@iss.net). References: http://support.microsoft.com/support/kb/articles/q126/7/13.asp http://www.infoworld.com/cgi-bin/displayStory.pl?971014.wntsecurity.htm X-Force Vulnerability and Threat Database: http://www.iss.net/xforce To receive these Alert Summaries, subscribe to the ISS Alert mailing list by sending an email to majordomo@iss.net and within the body of the message type: 'subscribe alert'. Internet Security Systems, Inc., (ISS) is the pioneer and world's leading supplier of network security assessment and monitoring tools, providing comprehensive software that enables organizations to proactively manage and minimize their network security risks. For more information, contact the company at (800) 776-2362 or (770) 395-0150 or visit the ISS Web site at http://www.iss.net. - -------- Copyright (c) 1997 by Internet Security Systems, Inc. Permission is hereby granted for the redistribution of this Alert Summary electronically. It is not to be edited in any way without express consent of X-Force. If you wish to reprint the whole or any part of this Alert Summary in any other medium excluding electronic medium, please email xforce@iss.net for permission. Disclaimer The information within this paper may change without notice. Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties with regard to this information. In no event shall the author be liable for any damages whatsoever arising out of or in connection with the use or spread of this information. Any use of this information is at the user's own risk. X-Force PGP Key available at: http://www.iss.net/xforce/sensitive.html Please send suggestions, updates, and comments to: X Force of Internet Security Systems, Inc. -----BEGIN PGP SIGNATURE----- Version: 2.6.2 iQCVAwUBNE5uEjRfJiV99eG9AQEKTQP8D+ZW5qQX6Sl1YoGO/pLoTwZwLhLswgGI DLvVGenkYmljP4VkEozjxePVVtnlKQadLm54iYzESpf9I3siJeuC0ZiUXKFUYz8U 85EH7LCqeNONa6bD0700RVIe/NFoLN7OkXnkvr5TooX4Kqkx+RyJu8fTu46mXSke 7iDg3DnrHkg= =np7I -----END PGP SIGNATURE-----