HP OpenVMS Systems Documentation

The security audit log file continues to grow until action is taken, so you must devise a plan for maintaining it.

Typically, sites rename each day's log file and create a new one. To open a new, clusterwide version of the security audit log file, use the following command:

$ SET AUDIT/SERVER=NEW_LOG

To create a new, node-specific log, precede the SET AUDIT/SERVER=NEW_LOG command with the command SET AUDIT/DESTINATION=filespec where the file specification includes a logical name that resolves to a node-specific file (for example, SYS$SPECIFIC:[SYSMGR]SECURITY).

Once you have opened the new log, rename the old version with a name that incorporates a beginning or ending date for the data.

To save space on the system disk, you may want to copy the file to another disk and delete the log from the system disk. Even sites with a dedicated auditing disk, which is common to environments with high security requirements, may want to relocate the old version to make space for future messages.

Once you archive the file, run the Audit Analysis utility on the old log (see Section 9.5.2). By archiving this file, you maintain a clusterwide history of auditing messages. If you ever discover a security threat on the system, you can analyze the archived log files for a trail of suspicious user activity during a specified period of time.

9.4.1.2 Moving the File from the System Disk

To relocate the file from the SYS$COMMON:[SYSMGR] directory, edit the command procedure SYSECURITY.COM. This procedure executes each time the system is rebooted, before the audit server is started.

To relocate the file, perform the following steps:

1. Change the startup sequence by adding a line to SYSECURITY.COM that directs the operating system to mount the designated auditing disk before the audit server process is started rather than after. For example:

   $ IF .NOT. F$GETDVI("$1$DUA2","MNT") - _$ THEN MOUNT/SYSTEM $1$DUA2 AUDIT AUDIT$ /NOREBUILD

   
   The command in this example mounts a volume labeled AUDIT on $1$DUA2 and makes it available systemwide. MOUNT also assigns the logical name AUDIT$.
2. Move the audit server database to the auditing disk, if you choose. The database remains small and fairly stable so this step is not essential.
   To move the database, add a second line to SYSECURITY.COM to define the system logical name VMS$AUDIT_SERVER. (The line follows the one that mounts the auditing disk.) In the command, define a system logical name and assign it to the VMS$AUDIT_SERVER data file on the disk with the logical name AUDIT$. For example:

   $ DEFINE/SYSTEM/EXEC VMS$AUDIT_SERVER AUDIT$:[AUDIT]VMS$AUDIT_SERVER.DAT

   
   This command redirects the audit server database to the volume on $1$DUA2, which was mounted in step 1.
3. From the DCL level, redirect the security audit log file to the volume mounted in SYSECURITY.COM (see step 1). Use the SET AUDIT command to update the audit server database with the new location of the security audit log file, and instruct the audit server process on each node in the cluster to begin using the file. For example:

   $ SET AUDIT/JOURNAL=SECURITY - _$ /DESTINATION=AUDIT$:[AUDIT]SECURITY

   
   Do not repeat this command on each system restart.
   If you use a logical name in the specification of the security audit log file, it must be defined as a /SYSTEM logical name in SYSECURITY.COM.

The operating system sends alarm messages to terminals enabled for security class messages. In most cases, these security alarms appear on the system console by default. Because messages scroll quickly off the screen, it is a good practice to enable a separate terminal for security class messages and disable message delivery to the system console. Choose either a terminal in a secure location that provides hardcopy output or have dedicated staff monitor the security operator terminal. Any number of terminals can be enabled as security operators.

To set up a terminal to receive security class alarms, enter the following DCL command from the designated terminal:

$ REPLY/ENABLE=SECURITY

For long-term use of a specific terminal, you can modify your site-specific startup command procedure to automatically enable the terminal. For example, the following command lines in a startup command procedure disable the delivery of security alarms to the system console and enable alarms on terminal TTA3:

$ DEFINE/USER SYS$COMMAND OPA0:
$ REPLY/DISABLE=SECURITY
$ DEFINE/USER SYS$COMMAND TTA3:
$ REPLY/ENABLE=SECURITY

The authorization and SYSGEN event classes occasionally produce such lengthy alarm messages that the messages get truncated. For this reason, it is best to enable these classes for both alarms and audits. When an alarm message is truncated, the text indicates it is incomplete. As long as you have enabled the classes for audit messages, you can use ANALYZE/AUDIT to display the complete message.

9.4.3 Secondary Destinations for Event Messages

The operator terminal and the audit log file are the primary destinations for security event messages. A site can choose to send copies of audit messages to a remote log file (called an archive file) or a listener mailbox.

9.4.3.1 Using a Remote Log File

The operating system allows workstations and other users with limited management resources to duplicate their audit log file on another node. This secondary log, the security archive file, is then available to a security administrator on a remote node who has the skills to analyze the file. In some situations, the archive file can also provide insurance should the local audit log file be tampered with in some way. One node can direct auditing messages to an archive file. Once enabled, the audit server writes a copy of each auditing message to the security archive file as well as to the security audit log file.

Use the following procedure to write security audit messages to a remote security archive file:

1. Log in to the node where the archive file is located, and create an account for the audit server. To the account, assign a user name like AUDIT_ARCHIVE; make the account unprivileged with only network access. Be sure the account has access to the device and directory containing the security archive file.

   $ SET DEFAULT SYS$SYSTEM $ RUN AUTHORIZE UAF> ADD AUDIT_ARCHIVE /ACCESS=NETWORK /DEVICE=WORK2- _UAF> /DIRECTORY=[AUDIT_ARCHIVE]

2. Add a proxy account on the remote node for AUDIT$SERVER. This allows the audit server process to write data to its account on the remote node. For example, the following commands grant the audit server process on node SMLNOD proxy access to the AUDIT_ARCHIVE account on node BIGNOD:

   UAF> ADD/PROXY SMLNOD::AUDIT$SERVER AUDIT_ARCHIVE/DEFAULT UAF> EXIT

   
   See Section 12.3.2 for further information about setting up proxy accounts.
3. Log out from the remote node. On the local node, enable archiving of the log file to the node by entering the following command:

   $ SET AUDIT/ARCHIVE=ALL/DESTINATION=BIGNOD::WORK2:- _$ [AUDIT_ARCHIVE]SMLNOD_MAY_93.AUDIT$JOURNAL

   
   You must supply a complete directory specification. If you include any logical names, ensure the local audit server process can translate them.

To create a new archive file, rename the current file; the next time the system starts up, it creates a new one for you.

If the network goes down, messages intended for the security archive file are lost. Security operator terminals receive notice of the lost connection and the number of lost messages. Once the network is up, the audit server reestablishes connection to the original archive file and continues writing event messages.

Analyzing the security archive file is identical, in most respects, to analysis of the security audit log file. You can analyze a remote security archive file at any time, even while the file is open. See Section 9.5 for more information.

9.4.3.2 Using a Listener Mailbox

As an additional feature of the security auditing facility, you can create a listener device to receive a binary copy of all security-auditing messages. (A listener device is a permanent or temporary mailbox that you create with the Create Mailbox [$CREMBX] system service.) You can set up an application to receive and process auditing information and react to events as they occur on the system. Each system can have one listener device, and it can receive only events that are occurring on the local node.

To enable the listener device to receive security-auditing messages, execute the SET AUDIT/LISTENER command in the following format:

For the device-name parameter, supply either the logical name specified when you created the mailbox or the equivalence name of the mailbox, in the form of MBAn, where n represents the unit number of the mailbox. If you create the device as a temporary mailbox, you must use the Get Device and Volume Information ($GETDVI) system service to return the mailbox device name.

To disable an audit listener device, enter the following command:

$ SET AUDIT/NOLISTENER

On VAX systems, refer to the files AUDSRV_LISTENER.B32 (a VAX BLISS program) and AUDSRV_LISTENER.MAR (a VAX MACRO program) in the SYS$EXAMPLES directory for examples of a program that processes audit-event messages sent to a listener mailbox on a DECtalk device.

9.5 Analyzing a Log File

Collecting security audit messages in the security audit log file is useless without periodically reviewing it for suspicious activity. You use the Audit Analysis utility (ANALYZE/AUDIT) to examine the data in the security audit log file.

ANALYZE/AUDIT generates a report from the log file so that you become familiar with normal activity on your system and can easily spot atypical activity. It summarizes events for you and plots where activity is occurring on the cluster. The utility also helps you analyze atypical activity because it is capable of selecting a subset of information from an audit report and of providing fuller information for your analysis. While the analysis of a single audit log file might not be significant, audit records can, over time, reveal a pattern of activity that indicates security violations.

9.5.1 Recommended Procedure

This section describes how to analyze audit log files on your system. Although the way you use ANALYZE/AUDIT depends upon the security needs at your site, there are a number of common steps that you should follow, regardless of the extent to which you use the utility. Before you can recognize potential security problems, you need to become familiar with the normal operation of your system. Then you can develop a procedure for generating and reviewing audit reports on a periodic basis. Whenever your regular analysis of audit log files leads you to suspect a security problem, you should perform a detailed investigation of selected security events.

Step 1: Know What Is Normal

As a security administrator, you should be able to answer the following questions before analyzing an audit log file:

• What are the typical hours of operation for most users of the system?
• Are there specific users who normally operate with advanced privileges?
• Which images generate system security events as part of other applications?
• Are there any regular batch or network jobs that run at specific times of the day?

By knowing the answers to these questions, you can eliminate false alarms, which otherwise may cause you to wrongly suspect a security problem.

Step 2: Periodically Analyze the Audit Report

The most common type of report to generate is a brief, daily listing of events. You can create a command procedure that runs in a batch job every evening before midnight to generate a report of the day's security event messages. (You can use the same procedure to create a new version of the audit log [see Section 9.4.1.1].)

The following example shows the ANALYZE/AUDIT command line to generate this report:

$ ANALYZE/AUDIT/SINCE=TODAY/OUTPUT=31DEC2000.AUDIT -    (1)
_$ SYS$MANAGER:SECURITY.AUDIT$JOURNAL
$ MAIL/SUBJECT="Security Events" 31DEC2000.AUDIT SYSTEM (2)

1. The first command in this example produces an audit report named 31DEC2000.AUDIT, which contains one-line descriptions of all the security event messages generated during the current day.
2. The second command mails the file to the security administrator for examination.

Depending on the number of security events that you are auditing on your system, it can be impractical to review every audit record written to the audit log file. In this case, you can select a specific set of records from the log file, such as all audit records related to changes in the authorization database and break-in attempts, or all events occurring outside normal business hours.

Analyze any subprocess-related audits with the knowledge that a pipe subprocess (created by the DCL PIPE command) can generate the audits. The PIPE command can create a large number of subprocesses to execute a single PIPE command. This can mean a potential increase in auditing events that are related to subprocess activities (for example, process creation, process deletion, login, logfailure, and logout).

It is important that you review audit reports as soon as possible. The sooner you inspect the reports, the sooner you become aware of any possible breach of security on the system and can determine the extent of the problem. You can make the inspection of the previous day's audit report a regular part of your morning routine, or you can create a program that reviews the report and notifies you through the Mail utility (MAIL) when suspicious events appear.

Step 3: Scrutinize Suspicious Activity

If, during your review, you find any security events that appear suspicious or out of place, like login attempts outside normal business hours, then use the Audit Analysis utility to perform a more detailed inspection of the security audit log file. A full report can help you determine which security events logged to the audit log file warrant a more thorough investigation.

The following command generates a full report of selected security audit records:

$ ANALYZE/AUDIT/FULL/SINCE=TODAY/OUTPUT=31DEC2000.AUDIT -
_$ /EVENT_TYPE=(BREAKIN,RIGHTSDB,SYSUAF)
$ MAIL/SUBJECT="Security Events" 31DEC2000.AUDIT SYSTEM

The audit report for December 31, 2000 contains information on all intrusion attempts and all modifications to the system user authorization file (SYSUAF.DAT) and the rights database (RIGHTSLIST.DAT).

9.5.2 Invoking the Audit Analysis Utility

The Audit Analysis utility is the tool you use to produce a meaningful report from a binary log file. This section and the sections that follow describe how to use the utility, but refer to the OpenVMS System Management Utilities Reference Manual for complete documentation of the utility's commands and qualifiers.

To invoke the Audit Analysis utility, use the following DCL command:

For the file-name parameter, substitute the name of the file from which audit reports are to be generated. The default name of the security audit log file is SECURITY.AUDIT$JOURNAL. You must specify the directory: SYS$MANAGER.

9.5.3 Providing Report Specifications

With the Audit Analysis utility, you are able to extract all or some of the security event messages from a single audit log and produce reports with various levels of detail.

The audit report reflects events from the set of event classes a site has enabled (see Section 9.2). You can tailor the report so only a subset of events are extracted. The selection criteria can be based on time, on event class, or on field of data within the event message. (See the documentation of the /SELECT qualifier in the OpenVMS System Management Utilities Reference Manual.) Table 9-6 summarizes the qualifiers that determine the content of the report.

ANALYZE/AUDIT produces audit reports in different formats (see Table 9-6). The utility produces a one-line summary of each record in the log file by default. Brief, one-line reports are most useful for routine analysis of a log file. The more detailed full reports provide the detail necessary for analyzing records of a suspicious nature. If you are interested in archiving portions of a log file, the binary listing lets you store a subset of an audit log file.

A summary report helps you identify potential security problems quickly. For each class of security event, a summary report can list the total number of audit messages extracted from the security audit log file being analyzed. A summary report can also display a plot of auditing activity, based on the system generating the event message, the time when it occurred, and the total number of events seen.

Example 9-4 shows a brief report of all the security audit events logged to the system security audit log file. In the ANALYZE/AUDIT command that generates the report, substitute the name of your audit log file.

$ ANALYZE/AUDIT/BRIEF SYS$MANAGER:SECURITY.AUDIT$JOURNAL

      Date / Time       Type     Subtype      Node   Username    ID    Term
------------------------------------------------------------------------------
 1-NOV-2000 16:00:03.37 ACCESS   FILE_ACCESS  HERE   SYSTEM   5B600AE4
 1-NOV-2000 16:00:59.66 LOGIN    SUBPROCESS   GONE   ROBINSON 3BA011D4
 1-NOV-2000 16:02:37.31 LOGIN    SUBPROCESS   GONE   MILANT   000000D5
 1-NOV-2000 16:06:36.40 LOGFAIL  LOCAL        SUPER  MBILLS   000000E5 _TTA1:
   .
   .
   .

Example 9-5 shows one record from a full format audit report. In the ANALYZE/AUDIT command that generates the report, substitute the name of your audit log file.

$ ANALYZE/AUDIT/FULL SYS$MANAGER:SECURITY.AUDIT$JOURNAL

Security audit (SECURITY) on FNORD, system id: 19728
Auditable event:          Object access
Event time:               6-AUG-2000 11:54:16.21
PID:                      3D200117
Process name:             Hobbit
Username:                 PATTERSON
Process owner:            [ACCOUNTING,PATTERSON]
Terminal name:            RTA1:
Object class name:        LOGICAL_NAME_TABLE
Object name:              LNM$SYSTEM_DIRECTORY
Access requested:         WRITE
Status:                   %SYSTEM-S-NORMAL, normal successful completion
Privileges used:          SYSPRV

Example 9-6 shows a summary report. In the ANALYZE/AUDIT command that generates the report, substitute the name of your audit log file.

$ ANALYZE/AUDIT/SUMMARY SYS$MANAGER:SECURITY.AUDIT$JOURNAL

Total records read:        9701          Records selected:          9701
Record buffer size:        1031
Successful logins:          542          Object creates:            1278
Successful logouts:         531          Object accesses:           3761
Login failures:              35          Object deaccesses:         2901
Breakin attempts:             2          Object deletes:             301
System UAF changes:          10          Volume (dis)mounts:          50
Rights db changes:            8          System time changes:          0
Netproxy changes:             5          Server messages:              0
Audit changes:                7          Connections:                  0
Installed db changes:        50          Process control audits:       0
Sysgen changes:               9          Privilege audits:            91
NCP command lines:          120