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| Updated: 11 December 1998 |
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| Updated: 11 December 1998 |
OpenVMS Guide to System Security
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You should regularly display the rights database to check that it is correct and current. Two AUTHORIZE commands are used for this: SHOW/IDENTIFIER and SHOW/RIGHTS. To display all holders of an identifier, use the SHOW/IDENTIFIER command, as shown in the following example:
UAF> SHOW/IDENTIFIER/FULL NETWORK |
Use the asterisk (*) wildcard to display all holders of all identifiers on the system, as follows:
UAF> SHOW/IDENTIFIER/FULL * |
To display the identifiers held by a particular user, use the SHOW/RIGHTS command, as follows:
UAF> SHOW/RIGHTS/USER=ROBIN |
Use the asterisk wildcard to display all identifiers held by all users, as follows:
UAF> SHOW/RIGHTS/USER=* UAF> SHOW/RIGHTS/USER=[*,*] |
The first command displays users alphabetically. The second command
displays users according to UICs.
8.6.2 Adding Identifiers
You add identifiers to the rights list with the AUTHORIZE command ADD/IDENTIFIER, for example:
UAF> ADD/IDENTIFIER PAYROLL identifier PAYROLL value %X80080011 added to RIGHTSLIST.DAT |
To grant users an identifier with any of the attributes described in Section 8.6.7, you must name that attribute when adding the identifier. For example, to allow users to add or modify an identifier, specify the Dynamic attribute:
UAF> ADD/IDENTIFIER PROJECT_TEAM1 /ATTRIBUTES=DYNAMIC |
If you accidentally deleted the rights list and it cannot be recovered from a backup copy, recreate RIGHTSLIST.DAT by entering the CREATE/RIGHTS command, followed by the ADD/IDENTIFIER command, as follows:
UAF> CREATE/RIGHTS
{message}
UAF> ADD/IDENTIFIER/USER=* or ADD/IDENTIFIER/USER=[*,*]
{messages}
|
The ADD/IDENTIFIER command generates a UIC identifier in the rights
list corresponding to each user name in SYSUAF.DAT. To complete the
task, use the ADD/IDENTIFIER command to add all general identifiers
that were lost. Then redefine the holders of the identifiers with
GRANT/IDENTIFIER commands, as described in Section 8.6.4.
8.6.4 Assigning Identifiers to Users
After adding identifiers, you associate users as holders of the existing identifiers by using the AUTHORIZE command GRANT/IDENTIFIER, as shown in the following example:
UAF> GRANT/IDENTIFIER PAYROLL MARTIN UAF-I-GRANTMSG, identifier PAYROLL granted to MARTIN UAF> GRANT/IDENTIFIER PAYROLL IPPOLITO UAF-I-GRANTMSG, identifier PAYROLL granted to IPPOLITO |
To give user Martin the EXECUTIVE identifier in addition to the PAYROLL identifier would require another use of the GRANT/IDENTIFIER command. You can introduce only one holder association at a time with the GRANT/IDENTIFIER command.
In all cases shown above, AUTHORIZE associates the PAYROLL identifier
with the UIC identifier corresponding to the user, specifically Martin
and Ippolito. Both the identifiers must exist in the rights database.
8.6.5 Removing Holder Records
When a user leaves the company, remove the UAF record for that user.
Notify the managers of all sites where that user has access to proxy
accounts to remove proxy access information in the remote node's
NETPROXY.DAT file. When you run AUTHORIZE to remove a user's UAF
record, AUTHORIZE also removes the user's connections as a holder of
identifiers in the rights database. However, if a departed user is the
only remaining holder of a given identifier, remove that identifier to
avoid future confusion.
8.6.6 Removing Identifiers
Before you remove an identifier from the rights database:
$ SET SECURITY/ACL=(IDENTIFIER=87SUMMER)- _$/DELETE/LOG *.*;* |
UAF> REMOVE/IDENTIFIER 87TERM3
{message}
|
Identifiers in hexadecimal format in an ACE indicate that a general identifier has been deleted from the rights database. Similarly, if you see an identifier displayed as a numeric UIC, the original identifier was a UIC that has been removed. Delete ACEs with numeric UIC or hexadecimal identifiers.
It is wise not to reuse UICs after an employee leaves. The new employee may gain some or all of the access rights of the previous employee through ACL entries that still reference the old UIC in numeric format.
To rename an identifier, use the AUTHORIZE command RENAME/IDENTIFIER in the following format:
RENAME/IDENTIFIER old-identifier new-identifier |
Renaming an identifier preserves the set of resources available through
that identifier. ACLs containing the renamed identifier automatically
display the new identifier name.
8.6.7 Customizing Identifiers
Whenever you add identifiers to the rights list or grant identifiers to users, you can stipulate that the identifier carry special characteristics called attributes. Although there are many possible attributes, most sites commonly use the following ones:
Sites with high security requirements are likely to use two other attributes, which discourage users from scanning the rights database:
| Holder Hidden attribute | Prevents someone from getting a list of users who hold an identifier unless that person owns the identifier. |
| Name Hidden attribute | Allows holders of an identifier to have it translated (either from binary to ASCII or vice versa), but prevents unauthorized users from translating the identifier. |
Read access to RIGHTSLIST.DAT overrides the Holder Hidden and Name Hidden attributes. The rights list by default denies access to world users; it has a protection of S:RWED,O;RWED,G:R,W:.
The following sections describe each attribute and explain when you
might want to add them to some of your site's identifiers.
8.6.7.1 Dynamic Attribute
Once you grant an identifier to a user, processes created by that user hold the identifier for the life of the process. However, if you grant the identifier with the Dynamic attribute, the user who holds the identifier can use the DCL command SET RIGHTS_LIST to add or remove the identifier or its attributes from the process rights list as needed.
To allow users to modify an identifier, specify the Dynamic attribute when adding the identifier to the rights database by using AUTHORIZE, as shown in the following example:
$ SET DEFAULT SYS$SYSTEM $ RUN AUTHORIZE UAF> ADD/IDENTIFIER MGMT101 /ATTRIBUTES=DYNAMIC |
To allow specific holders of the identifier to modify the identifier, include the Dynamic attribute when granting the identifier, as follows:
UAF> GRANT/IDENTIFIER MGMT101/ATTRIBUTES=DYNAMIC SCHWARTZ |
User Schwartz could then use the following command to remove the MGMT101 identifier from the process rights list:
$ SET RIGHTS_LIST/DISABLE MGMT101 |
Users who hold identifiers with the Dynamic and Resource attributes can also use the SET RIGHTS_LIST command to remove only the Resource attribute on the identifier.
Because users might be able to circumvent intended security policy by
removing their identifiers, be careful when granting users an
identifier with the Dynamic attribute. If an identifier is used in an
ACL to deny access to users who hold that identifier with the Dynamic
attribute, users may be able to gain access to the object through
another ACL entry by removing the identifier from their process rights
lists.
8.6.7.2 Holder Hidden Attribute
Sites with high security requirements can conceal the holders of certain identifiers, thereby preventing malicious users from determining which accounts are more interesting to target for break-ins.
You place the attribute on an identifier the user holds by using the AUTHORIZE command MODIFY/IDENTIFIER, for example:
UAF> MODIFY/IDENTIFIER /ATTRIBUTES=HOLDER_HIDDEN SECRET_PROJECT |
Now the prober cannot discover who is on the secret project.
8.6.7.3 Name Hidden Attribute
Sites with high security requirements can hide the names of identifiers. For example, sites implementing mandatory access controls can hide the names of identifiers associated with their security categories. This prevents people from seeing the names of identifiers unless they personally hold them. When an identifier holds the Name Hidden attribute, the operating system refuses to translate the identifier from its binary value to ASCII or from ASCII to the binary value unless the requesting process holds the identifier.
To assign the attribute to an identifier, use the AUTHORIZE command MODIFY/IDENTIFIER:
UAF> MODIFY/IDENTIFIER SECRET_NEWS /ATTRIBUTES=NAME_HIDDEN |
The No Access attribute allows a process to hold an identifier but not have the identifier considered in determining access rights to the object.
For example, a user with the Resource and No Access attributes can charge disk space to the identifier but not have access to objects owned by the identifier. Or a system manager can manage data and perform tasks connected with the data but cannot read from or write to any of the files.
You can allow file space to be owned by and charged to an identifier yet prevent the files from being accessed in any way. Use AUTHORIZE to specify the No Access attribute with the Resource attribute when adding the identifier to the rights database, as shown in the following example:
UAF> ADD/IDENTIFIER/ATTRIBUTES=(RESOURCE,NOACCESS)- _UAF> MGMT101 |
To limit the rights of users holding an identifier with the Resource attribute, grant the identifier with the No Access attribute as well as the Resource attribute to all desired users:
UAF> GRANT/IDENTIFIER/ATTRIBUTES=(RESOURCE,NOACCESS)- _UAF> MGMT101 SCHWARTZ |
Consumption of disk space is generally charged to the creator of each file by subtracting the disk space from the file owner's disk quota. System managers and security administrators might prefer to track the use of disk space according to logical groups of users (such as departments or projects) rather than individual users. General identifiers are used to specify these groups. Thus, when general identifiers own directories, disk space used by files created in the directories may be charged to the identifier rather than the UIC of the file's creator.
To allow file space to be owned by and charged to an identifier, use AUTHORIZE to specify the Resource attribute when adding the identifier to the rights database, as shown in the following example:
UAF> ADD/IDENTIFIER MGMT101 /ATTRIBUTES=RESOURCE |
To allow specific holders of the identifier to charge disk space to the identifier, perform the following steps:
UAF> GRANT/IDENTIFIER MGMT101/ATTRIBUTES=RESOURCE SCHWARTZ |
$ SET SECURITY/ACL=(- _$ (IDENTIFIER=MGMT101,ACCESS=READ+WRITE ) - _$ (IDENTIFIER=MGMT101,OPTIONS=DEFAULT,ACCESS=READ+WRITE))- _$ INVENTORY.DIR |
$ SET SECURITY/OWNER=MGMT01 INVENTORY.DIR |
Because resource identifier MGMT101 is going to own any file you create in directory INVENTORY.DIR, you use ACEs to determine the type of file access you receive. Include a Creator ACE (CREATOR,ACCESS=READ+WRITE+EXECUTE+DELETE) to set the access granted to the file's creator. Alternatively, you can let the system assign an ACE; its ACE grants control access to the file's creator plus the access specified in the owner field of the protection code. You can set up the protection code by including a Default Protection ACE in the ACL for INVENTORY.DIR, for example, (DEFAULT_PROTECTION, ACCESS=O:RW). (Refer to Section 8.8.1.2 for further information.)
Not everyone who holds the identifier will also hold the Resource
attribute associated with that identifier. If you create a file in a
directory owned by an identifier but you do not have the Resource
attribute for that identifier, the file will be owned by your UIC, and
the required disk space is subtracted from your disk quota.
8.6.7.6 Subsystem Attribute
You can authorize users to manage protected subsystems by granting them a subsystem identifier with the Subsystem attribute. This empowers users to enable images to access the objects managed by the subsystem. (See Chapter 13 for a discussion of protected subsystems.)
In the following example, user Schwartz is given the authority to create a subsystem with the identifier MAIL_SUBSYSTEM. Schwartz is also given control access to the application image to set access controls.
$ SET DEFAULT SYS$SYSTEM $ RUN AUTHORIZE UAF> ADD/IDENTIFIER MAIL_SUBSYSTEM /ATTRIBUTES=SUBSYSTEM UAF> GRANT/IDENTIFIER MAIL_SUBSYSTEM - _UAF> /ATTRIBUTES=SUBSYSTEM SCHWARTZ UAF> Exit $ SET SECURITY/ACL=(IDENTIFIER=MAIL_SUBSYSTEM,ACCESS=CONTROL)- _$ MEMBER_LIST.EXE |
As a privileged security administrator, you can use the SET RIGHTS_LIST command to modify the rights list of any process on the system or to modify identifiers in the system rights list. Adding an identifier to the system rights list effectively grants it to all users. You can also use the SET RIGHTS_LIST command to add attributes to existing identifiers.
A possible use of the system rights list is to enable site-specific environmental conditions. For example, a batch job scheduled to run at 8:00 a.m. could add the following identifier:
$ SET RIGHTS_LIST/SYSTEM/ENABLE DAY_SHIFT |
Another batch job scheduled for 5:00 p.m. could remove the identifier DAY_SHIFT:
$ SET RIGHTS_LIST/SYSTEM/DISABLE DAY_SHIFT |
The effect is to enable access to protected objects with the identifier DAY_SHIFT during the 8:00 a.m. to 5:00 p.m. period.
The command in the next example modifies a process rights list by adding the SALES identifier to the rights list of the process DEDNAM. Specifying the Resource attribute allows the holders of the SALES identifier to charge disk space to it.
$ SET RIGHTS_LIST/ENABLE/ATTRIBUTES=RESOURCE/PROCESS=DEDNAM SALES |
Some system activities are limited to users who hold specific privileges. These restrictions protect the integrity of the operating system's performance and, thus, the integrity of service provided to users. Grant privileges to each user on the basis of two factors: (a) whether the user has a legitimate need for the privilege and (b) whether the user has the skill and experience to use the privilege without disrupting the system.
A user's privileges are recorded in the user's UAF record in two privilege vectors. One vector stores the authorized privileges, and the other vector stores the default privileges. The default privileges are the subset of authorized privileges that a user process receives at login.
When a user logs in to the system, the user's privilege vector is stored in the header of the user's process. In this way, the user's privileges are passed on to the process created for the user. Users can use the DCL command SET PROCESS/PRIVILEGES to enable and disable privileges for which they are authorized.
The operating system monitors and audits the use of privilege. You can
enable auditing for specific privileges and examine the audit log file
to see what privileges were used to execute DCL commands or system
services. See Chapter 9 for further information.
8.7.1 Categories of Privilege
Privileges are divided into the following seven categories according to the damage that the user possessing them could cause the system:
Table 8-2 categorizes the privileges and includes a brief definition of the powers associated with each privilege.
| Category | Privilege | Activity Permitted |
|---|---|---|
| None | None | Denied activities requiring privileges |
| Normal |
NETMBX
TMPMBX |
Create network connections
Create temporary mailbox |
| Group |
GROUP
GRPPRV |
Control processes in the same group
Gain access through the system protection field of the group's objects |
| Devour |
ACNT
ALLSPOOL BUGCHK EXQUOTA GRPNAM PRMCEB PRMGBL PRMMBX SHMEM |
Disable accounting
Allocate spooled devices Make bugcheck error log entries Exceed disk quotas Insert group logical names in the name table Create/delete permanent common event flag clusters Create permanent global sections Create permanent mailboxes Create/delete structures in shared memory |
| System |
ALTPRI
AUDIT OPER PSWAPM WORLD SECURITY SYSLCK |
Set base priority higher than allotment
Generate audit records Perform operator functions Change process swap mode Control any process Perform security-related functions Lock systemwide resources |
| Objects |
DIAGNOSE
IMPORT MOUNT READALL SYSGBL VOLPRO |
Diagnose devices
Mount a nonlabeled tape volume Execute mount volume QIO Possess read access to all system objects Create systemwide global sections Override volume protection |
| All |
BYPASS
CMEXEC CMKRNL IMPERSONATE DOWNGRADE LOG_IO PFNMAP PHY_IO SETPRV SHARE SYSNAM SYSPRV UPGRADE |
Disregard protection
Change to executive mode Change to kernel mode Create detached processes of arbitrary UIC Write to a lower secrecy object or lower an object's classification Issue logical I/O requests Map to specific physical pages Issue physical I/O requests Enable any privilege Access devices allocated to other users Insert system logical names in the name table Access objects through the system protection field Write to a higher integrity object or raise an object's integrity level |
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