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_____________________________________________________ The Computer Incident Advisory Capability ___ __ __ _ ___ / | / \ / \___ __|__ /___\ \___ _____________________________________________________ INFORMATION BULLETIN VAX/VMS Security Vulnerability in MONITOR August 24, 1992, 1200 PDT Number C-30 ________________________________________________________________________ PROBLEM: The MONITOR utility on VMS versions 5.0 thru 5.4-2 can be used to obtain unauthorized privileges. PLATFORM: VAX systems running the VMS operating system. DAMAGE: An unprivileged user can obtain all privileges. SOLUTION: Upgrade to VMS version 5.4-3 (or higher); alternatively disable or restrict access to MONITOR. ________________________________________________________________________ Critical Information About MONITOR Vulnerability CIAC is forwarding Digital Equipment Corporation's Software Security Response Team's (SSRT) advisory regarding this problem. While CIAC believes the information contained to be accurate, SSRT is fully responsible for its contents. DEC requires its advisory be redistributed intact. CIAC and DEC recommend upgrading VMS to the latest version. However, if you are unable to upgrade, there is a workaround described in the following DEC Advisory: =============================================================================== SSRT-0200 PROBLEM: Potential Security Vulnerability Identified in MONITOR SOURCE: Digital Equipment Corporation AUTHOR: Software Security Response Team - U.S. Colorado Springs USA PRODUCT: VMS Symptoms Identified On: VMS, Versions 5.0, 5.0-1, 5.0-2, 5.1, 5.1-B, 5.1-1, 5.1-2, 5.2, 5.2-1, 5.3, 5.3-1, 5.3-2, 5.4, 5.4-1, 5.4-2 ******************************************************* SOLUTION: This problem is not present in VMS V5.4-3 (released in October 1991) through VMS V5.5-1 (released in July, 1992). ******************************************************* Copyright (c) Digital Equipment Corporation, 1992 All Rights Reserved. Published Rights Reserved Under The Copyright Laws Of The United States. ------------------------------------------------------------------------------- PROBLEM/IMPACT: ------------------------------------------------------------------------------- Unauthorized privileges may be expanded to authorized users of a system under certain conditions, via the MONITOR utility. Should a system be compromised through unauthorized access, there is a risk of potential damage to a system environment. This problem will not permit unauthorized access entry, as individuals attempting to gain unauthorized access will continue to be denied through the standard VMS security mechanisms. ------------------------------------------------------------------------------- SOLUTION: ------------------------------------------------------------------------------- This potential vulnerability does not exist in VMS V5.4-3 (released in October 1991) and later versions of VMS through V5.5-1. Digital strongly recommends that you upgrade to a minimum of VMS V5.4-3, and further, to the latest release of VMS V5.5-1 (released in July, 1992). ------------------------------------------------------------------------------- INFORMATION: ------------------------------------------------------------------------------- If you cannot upgrade at this time, Digital recommends that you implement a workaround (examples attached below) to avoid any potential vulnerability. As always, Digital recommends that you periodically review your system management and security procedures. Digital will continue to review and enhance the security features of its products and work with customers to maintain and improve the security and integrity of their systems. ------------------------------------------------------------------------------- WORKAROUND ------------------------------------------------------------------------------- A suggested workaround would be to remove the installed image SYS$SHARE:SPISHR.EXE via VMS INSTALL and/or restrict the use of the MONITOR utility to "privileged" system administrators. Below are the examples of doing both. [1] To disable the MONITOR utility the image SYS$SHARE:SPISHR.EXE should be deinstalled from a privileged account. For cluster configurations; --------------------------- $ MC SYSMAN SYSMAN> SET ENVIRONMENT/CLUSTER SYSMAN> DO INSTALL REMOVE SYS$SHARE:SPISHR.EXE SYSMAN> DO RENAME SYS$SHARE:SPISHR.EXE SPISHR.HOLD SYSMAN> EXIT For non-VAXcluster configurations; --------------------------------- $ INSTALL INSTALL> REMOVE SYS$SHARE:SPISHR.EXE INSTALL> EXIT $ RENAME SYS$SHARE:SPISHR.EXE SPISHR.HOLD [2] If you wish to restrict access to the MONITOR command so that only a limited number of authorized (or privileged) persons are granted access to the utility, one method might be to issue the following commands from a privileged account; For cluster configurations; --------------------------- $ MC SYSMAN SYSMAN> SET ENVIRONMENT/CLUSTER SYSMAN> DO INSTALL REMOVE SYS$SHARE:SPISHR.EXE SYSMAN> DO SET FILE/ACL=(ID=*,ACCESS=NONE) SYS$SHARE:SPISHR.EXE SYSMAN> DO SET FILE/ACL=(ID=SYSTEM,ACCESS=READ+EXECUTE) SYS$SHARE:SPISHR.EXE SYSMAN> DO INSTALL ADD SYS$SHARE:SPISHR.EXE/OPEN/HEADER/SHARE/PROTECT SYSMAN> EXIT $ THIS WILL IMPACT the MONITOR UTILITY FOR REMOTE MONITORING. LOCAL USE OF MONITOR WILL CONTINUE TO WORK FOR PERSONS HOLDING THE ID's GRANTED ACL ACCESS. see additional note(s) below For non-VAXcluster configurations; ---------------------------------- $ INSTALL INSTALL> REMOVE SYS$SHARE:SPISHR.EXE INSTALL> EXIT $ SET FILE /ACL=(ID=*,ACCESS=NONE) SYS$SHARE:SPISHR.EXE $ SET FILE /ACL=(ID=SYSTEM,ACCESS=READ+EXECUTE) SYS$SHARE:SPISHR.EXE $ INSTALL INSTALL> ADD SYS$SHARE:SPISHR.EXE/OPEN/HEADER/SHARE/PROTECT INSTALL> EXIT $ NOTE in the above examples: The "SET FILE /ACL" line should be repeated for all accounts that are required/allowed to use the DCL MONITOR command. The ID -SYSTEM- should be replaced with valid user ID's that are to be associated with accounts you wish to grant access to. End of DEC Advisory =============================================================================== If you require additional assistance or wish to report a vulnerability, call CIAC at (510) 422-8193/FTS or send e-mail to ciac@llnl.gov. FAX messages to: (510) 423-8002/FTS. For emergencies only, call 1-800-SKYPAGE and enter PIN number 855-0070 (primary) or 855-0074 (secondary). The CIAC Bulletin Board, Felicia, can be accessed at 1200 or 2400 baud at (510) 423-4753/FTS and 9600 baud at (510) 423-3331/FTS. Previous CIAC bulletins and other information is available via anonymous ftp from irbis.llnl.gov (ip address 128.115.19.60). CIAC wishes to thank Rich Boren of DEC's SSRT for assistance and the advisory used in this bulletin. PLEASE NOTE: Many users outside of the DOE and ESnet computing communities receive CIAC bulletins. If you are not part of these communities, please contact your agency's response team to report incidents. Some of the other teams include the NASA NSI response team, DARPA's CERT/CC, NAVCIRT, and the Air Force response team. Your agency's team will coordinate with CIAC. This document was prepared as an account of work sponsored by an agency of the United States Government. 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