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OpenVMS Guide to System Security


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Those versions of OpenVMS that have been evaluated by the National Computer Security Center (NCSC) are listed in the Evaluated Products List, which is available from the following source:

This information is also available on the World Wide Web site at:

http://www.radium.NCSC.mil/tpep/epl/index.html 

The security protection provided by OpenVMS VAX Version 6.1 and OpenVMS Alpha Version 6.1 has been evaluated by the National Computer Security Center (NCSC) against the requirements specified by the "Department of Defense Trusted Computer System Evaluation Criteria" dated December 1985. OpenVMS VAX Version 6.1 and OpenVMS Alpha Version 6.1 have been given a C2 rating.

C.1 Introduction to C2 Systems

This section describes the requirements for a C2 system and explains the documentation that the OpenVMS product provides to support such a system.

C.1.1 Definition of the C2 Environment

A C2 environment is one that meets the United States Defense Department's criteria for trusted computer systems and that contains only those hardware and software components of the trusted computing base (TCB) that were included in the government's evaluation of the OpenVMS operating system.

The criteria for C2 systems are defined in the Department of Defense Trusted Computer System Evaluation Criteria, published by the Department of Defense Computer Security Center (DOD 5200.28-STD). They include the following:

C.1.2 Documentation

The trusted facility manual is intended for the system administrator. The C2 trusted facility manual includes the following:

Part 1 and Part 2 of this guide constitute the security features user's guide and should be made available to all users.

C.2 Trusted Computing Base (TCB) for C2 Systems

The federal government's evaluation of a computer system measures the trusted computing base (TCB) against the criteria summarized in Section C.1.1. The TCB is a combination of computer hardware and an operating system that enforces a security policy.

C.2.1 Hardware in the TCB

The architectural design of VAX processors prevent competing programs from interfering with the data of another program. VAX hardware prevents one program from interfering with the memory of another program.

The security features described in this guide apply to any VAX processor in the evaluated hardware configurations and to all supported mass storage and communications devices. The Final Evaluation Report, Digital Equipment Corporation, OpenVMS VAX and SEVMS Version 6.1 provides a full listing of the evaluated hardware.

C.2.2 Software in the TCB

In OpenVMS operating systems, the TCB encompasses much of the operating system. It includes the entire executive and file system, all other system components that do not execute in user mode (such as device drivers, RMS, and DCL), most system programs installed with privilege, and a variety of other utilities used by system managers to maintain data relevant to the TCB.

As a convenience to customers, the OpenVMS operating system ships with more than the base operating system. The software package includes save sets and supportive images for layered products typically run on OpenVMS operating systems. Yet only the base operating system was evaluated as a C2 system. Layered products, such as DECwindows software and Display PostScript support, were not part of the evaluation. For this reason, the C2 rating does not extend to OpenVMS VAX systems running the software listed in Table C-1. The exclusion of these software components in no way implies they are insecure; it means only they were not part of the evaluated system. After the introduction of any such software, the base system must be accredited for its particular usage.

Table C-1 Software Not Included in the C2-Evaluated System
Software Function Description
DECwindows software Windowing
interface
DECwindows is a layered product. Although DECwindows has been designed to meet the C2 requirements, it has not been evaluated.
DECdns distributed name service Client support DECdns software requires server software, which is a layered product. A cluster can make DECnet connections independently of DECdns.
DECamds software Monitoring and diagnostics DECamds software is outside the domain of the evaluated configuration.
LASTport and LASTport/DISK protocols Protocol support Digital's Infoserver products, which are outside the security domain of a clustered system, depend on these protocols.
LAT protocol Protocol support The LAT protocol is used for connections to DECserver terminal servers, which are outside the domain of the evaluated configuration.
DECnet/OSI Full Names Protocol support Support of the use of DECnet/OSI (Phase V) node names within the OpenVMS operating system. Use of this feature is not in the C2 evaluated configuration.
HSM (Hierarchial Shelving Manager) Storage Support File Shelving is a layered product. Use of the File Shelving facility (HSM) is not supported in the C2 evaluated configuration.
MME (Media Management Extension) Client Support Media Management Extension (MME) allows the use of storage media programs. Use of media management is outside of the domain of the C2 evaluated configuration.
OpenVMS Management Station The OpenVMS Management Station provides PC-based system management tools for OpenVMS. The OpenVMS Management Station has not been validated in a C2 evaluated configuration.
Access control strings File access on a remote node Use proxy accounts instead of access control strings in an evaluated configuration.

C.2.3 Site-Specific Additions to the TCB

Site-specific additions to the evaulated TCB hardware and software discussed in Section C.2.1 and Section C.2.2 include any of the following:

Typical site additions may include DECwindows software, LOGINOUT callouts, and other privileged Digital or third-party products.

Before you add layered products, become familiar with the behavior of these products and understand their impact on your existing system. Also study the the SYSMAN database, from which layered products can be started, in the context of a C2 environment.

All site-specific additions to the trusted computing base (TCB) must be controlled. The C2 rating applies only to the software and hardware components described in the Final Evaluation Report, Digital Equipment Corporation, OpenVMS VAX and SEVMS Version 6.1. If additional software or hardware is added to the TCB, the new TCB must go through a system certification to demonstrate its compliance with the C2 criteria.

C.3 Protecting Objects

The OpenVMS operating system controls access to objects that contain information. Protected objects include ODS-2 disk files, common event flag clusters, devices, all group and system global sections, logical name tables, queues, resource domains, and ODS-2 disk volumes. The capability object and the security class object enjoy full discretionary access protection but they are not objects according to the C2 evaluation criteria.

Chapter 4 and Chapter 5 describe object protection and explain how the operating system provides template profiles so all new objects have UICs, protection codes and, possibly, ACLs. Section 4.4.7, Section 4.5.6, and Section 8.8, in particular, explain how to set default protection for newly created objects.

The default protections assigned to global section and mailbox objects are less restrictive than those assigned to other objects. This is due to the fact that certain software products assume that mailbox and global section objects are created, by default, with the less restrictive protections. You can modify the template profiles for these objects so they have more stringent protection, but do keep in mind that some software products may be adversely affected.

To change the default protection, you need to modify both the template profile for the object and any existing object. For example, the following command modifies the MAILBOX template for the device class:

$ SET SECURITY/CLASS=SECURITY_CLASS/PROFILE=TEMPLATE=MAILBOX -
_$ /PROTECTION=(S:RWPL,O:RWPL,G,W) DEVICE

The operating system applies this value to all new mailboxes. The protection on each existing mailbox still has to be made more restrictive using the SET SECURITY command. For example:

$ SET SECURITY/CLASS=DEVICE -
_$ /PROTECTION=(S:RWPL,O:RWPL,G,W) mailbox_name

The default object protections specified in security templates survive system shutdown and reboot, so rebooting the system automatically ensures that all objects created after the reboot are created with the new default protections unless an object's creator specifies an alternate protection.

C.4 Protecting the TCB

The code and data that make up the OpenVMS TCB reside in files and, in part, in the address space of the running operating system. They are protected by the use of file access controls and memory page protection. Memory page protection is set up by the operating system as it executes and is normally not of concern to the system manager.

C.4.1 Protecting Files

The files comprising the TCB are correctly protected when the operating system is installed; however, the protection can be altered by sufficiently privileged users. Appendix B of this guide describes the correct file protection of operating system files.

When installing an OpenVMS operating system, avoid modifying any system files except those specific to your site. You want to maintain the security of the base operating system.

C.4.2 Privileges for Trusted Users

Certain privileges allow the holder to bypass normal file and memory access controls directly or indirectly and, therefore, must not be granted to persons other than the system manager, security administrator, or other trusted users. Privileges in four categories are appropriate only for trusted users: Objects, All, System, and Group. Refer to Table 8-2 for the privileges belonging to each of these categories. The privileges themselves are described in detail in Appendix A.

Privileges in the Objects and All categories allow the holder to violate the isolation of the TCB from untrusted users. Privileges in the System category allow the holder to interfere with normal system operation and cause denial of service, but they do not allow the holder to actually violate object access controls. Some privileges in the System category also allow access controls to be ultimately bypassed.

Privileges in the Group category permit the holder to interfere with the operations of others in the same group. The GRPPRV privilege, in particular, permits the holder to violate normal access controls within that holder's group because it grants access (through the system field of the protection code) to objects owned by subjects sharing the same group UIC.

All trusted users should be familiar with all the effects of any operations they perform. In particular, they need to know all software products an operation might use because a trusted user's privileges can allow untrusted software to perform operations that OpenVMS security policy would otherwise preclude.

C.4.3 Privileges for Untrusted Users

Untrusted users can hold any privilege in the Normal and Devour category with the exception of GRPNAM. Exercise caution in granting privileges from the Devour category, however, for they permit the holder to consume resources without limit, thereby causing possible denial of service and interference with the operations of other users on the system. Table C-2 lists privileges allowed to untrusted users.

Table C-2 Privileges for Untrusted Users
Category Privilege Activity Permitted
Normal NETMBX
TMPMBX
Create network connections
Create temporary mailbox
Devour ACNT
ALLSPOOL
BUGCHK
EXQUOTA
PRMCEB
PRMGBL
PRMMBX
SHMEM
Disable accounting
Allocate spooled devices
Make bugcheck error log entries
Exceed disk quotas
Create/delete permanent common event flag clusters
Create permanent global sections
Create permanent mailboxes
Create/delete structures in shared memory

C.4.4 Physical Security

Physical and environmental security are critical to the secure operation of the system. All physical components of the TCB require adequate protection, or unauthorized people can jeopardize the system's security. Because the following practices and features jeopardize the security of the TCB, they must not be used in a C2 environment:

C.5 Configuring a C2 System

This section discusses C2 constraints on the use of OpenVMS features. It includes the following topics:

C.5.1 Keeping Individuals Accountable

The proper use of names, UICs, and passwords ensures that individual accountability is enforced by the OpenVMS operating system. As a general practice, Digital recommends that you use generated passwords on privileged accounts. Because the following practices and features result in the loss of individual accountability, they must not be used in a C2 environment:

C.5.2 Managing the Auditing Trail

The security-auditing system lets you to track security-relevant activity on the system provided you manage it correctly. To follow a trail of activity in the audit logs, you must have complete and accurate records. Security event messages can be recorded in the security audit log file and on any terminal designated to receive security-class event messages. Because the following practices jeopardize a site's ability to track security-relevant events in the system, they must not be used in a C2 environment:

C.5.3 Reusing Objects

Before allocating memory or protected objects like volumes and devices to new users, sites must ensure that they are free of old data. The memory management subsystem protects against the reuse of system memory pages, and it cannot be defeated. Because the following practices jeopardize the clearing of old data from volumes and terminals before reallocation, they must not be followed in a C2 environment:

Digital recommends that sites clear printers between jobs to ensure that print jobs do not interfere with one another. A security administrator can reset printers automatically at the start or end (or both) of each job by associating a device control library with the print queue. Consult the documentation supplied with your printer to determine the appropriate reset sequence, and then refer to the OpenVMS System Manager's Manual for directions on adding that sequence to a library and associating the library with the queue.

C.5.4 Configuring Clusters

All valid cluster configurations, when configured as common environment clusters, fully support the OpenVMS security features. Because the following practices and features result in the loss of a common environment cluster, they must not be used in a C2 environment.


Note

OpenVMS clusters can consist of VAX and Alpha nodes.

C.5.5 Starting Up and Operating the System

A C2 system is the shipped system that has been configured according to the guidelines in this appendix. When configuring your system, you must observe the following guidelines:

C.5.6 Forcing Immediate Reauthentication of a Specified Subject After a Change in Access Rights

A system or security administrator may force an untrusted subject to reauthenticate himself or herself at any time. This might be necessary when the subject's access rights have been modified. The procedure is as follows and can be performed only by a trusted subject.

  1. Make the changes to the subject's authorization record in the authorization file.
  2. Obtain the owner's UIC of the subject from the authorization file.
  3. Enter the SYSMAN utility.
  4. Use the SYSMAN utility to identify all processes owned by the subject.
    1. In an OpenVMS Cluster environment, set the SYSMAN environment clusterwide. If you are not in an OpenVMS Cluster environment, skip this step.
    2. Use SYSMAN DO SHOW SYSTEM/FULL to obtain a listing of all processes on the system or OpenVMS cluster. This command also lists the owner UIC and system PID of each process. Record this information.
  5. From SYSMAN, stop every process on every system that is owned by the subject.
    Note: Any process created by the subject after Step 4 is bound by the new access rights and does not need to be deleted. Therefore, this is not a recursive procedure.
    1. In the OpenVMS cluster environment, set the SYSMAN environment to point to only one node. If you are not in the OpenVMS cluster environment, skip this step.
    2. For each process on the system to be deleted, identify the PID from Step 2 and use the SYSMAN DO STOP/ID=pid command to stop the job.
    3. Repeat Steps a and b until all desired processes on all nodes of the cluster have been stopped.

C.6 Checklist for Generating a C2 System

The previous sections of this appendix describe the U.S. government requirements for running the OpenVMS operating system in a C2 environment. The following list reviews the government's security requirements:

Installing the System

Using Evaluated Components

Making Individuals Accountable

Managing the Audit Reporting System

Reusing Disks, Tapes, and Terminals

Building a Single Security Domain

Starting the System


Appendix D
Alarm Messages

This appendix describes alarm messages that result from auditing various system events. See Chapter 9 for a discussion of the auditing system and see the OpenVMS System Management Utilities Reference Manual for a description of the record format of audit messages.


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