VMware vSphere 7.0 vCenter Appliance PostgreSQL Security Technical Implementation Guide

Database management includes the ability to control the number of users and user sessions utilizing a database management system (DBMS). Unlimited concurrent connections to the DBMS could allow a successful denial-of-service (DoS) attack by exhausting connection resources, and a system can also fail or be degraded by an overload of legitimate users. Limiting the number of concurrent sessions per user is helpful in reducing these risks. VMware Postgres as deployed on the vCenter Service Appliance (VCSA) comes preconfigured with a "max_connections" limit that is appropriate for all tested, supported scenarios. The out-of-the-box configuration is dynamic, based on a lower limit plus allowances for the resources assigned to VCSA and the deployment size. However, this number will always be between 100 and 1000 (inclusive).

Without the capability to generate audit records, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. As an embedded database that is only accessible via "localhost", VMware Postgres on the vCenter Server Appliance (VCSA) does not implement robust auditing. However, it can and must be configured to log reasonable levels of information relating to user actions to enable proper troubleshooting. Satisfies: SRG-APP-000089-DB-000064, SRG-APP-000095-DB-000039, SRG-APP-000096-DB-000040, SRG-APP-000097-DB-000041, SRG-APP-000098-DB-000042, SRG-APP-000099-DB-000043, SRG-APP-000100-DB-000201, SRG-APP-000101-DB-000044, SRG-APP-000375-DB-000323

VMware Postgres has a few configuration files that directly control the security posture of the database management system (DBMS). Protecting these files from unauthorized access and modification is fundamental to ensuring the security of VMware Postgres. Satisfies: SRG-APP-000090-DB-000065, SRG-APP-000121-DB-000202, SRG-APP-000122-DB-000203, SRG-APP-000123-DB-000204, SRG-APP-000380-DB-000360

Without proper configuration, log files for VMware Postgres can grow without bound, filling the partition and potentially affecting the availability of the vCenter Server Appliance (VCSA). One part of this configuration is to ensure the logging subsystem overwrites, rather than appends to, any previous logs that would share the same name. This is avoided in other configuration steps, but this best practice should be followed for good measure.

If audit data were to become compromised, competent forensic analysis and discovery of the true source of potentially malicious system activity would be difficult, if not impossible, to achieve. In addition, access to audit records provides information an attacker could use to their advantage. To ensure the veracity of audit data, the information system and/or the application must protect audit information from all unauthorized access. This includes read, write, copy, etc. Satisfies: SRG-APP-000118-DB-000059, SRG-APP-000119-DB-000060, SRG-APP-000120-DB-000061

Within the database, object ownership implies full privileges to the owned object, including the privilege to assign access to the owned objects to other subjects. Database functions and procedures can be coded using definer's rights. This allows anyone who uses the object to perform the actions if they are the owner. If not properly managed, this can lead to privileged actions being taken by unauthorized individuals. VCDB is configured out of the box to be owned by the "vc" Postgres user. This configuration must be verified and maintained.

If VMware Postgres were to allow any user to make changes to database structure or logic, those changes might be implemented without undergoing the appropriate testing and approvals that are part of a robust change management process. Only qualified and authorized individuals must be allowed to obtain access to information system components to initiate changes, including upgrades and modifications. Unmanaged changes that occur to the database software libraries or configuration can lead to unauthorized or compromised installations.

To prevent unauthorized connection of devices, unauthorized transfer of information, or unauthorized tunneling (i.e., embedding of data types within data types), organizations must disable or restrict unused or unnecessary physical and logical ports, protocols, and services on information systems. Applications are capable of providing a wide variety of functions and services. Some of the functions and services provided by default may not be necessary to support essential organizational operations. Additionally, it is sometimes convenient to provide multiple services from a single component (e.g., email and web services); however, doing so increases risk over limiting the services provided by any one component. To support the requirements and principles of least functionality, the application must support the organizational requirements providing only essential capabilities and limiting the use of ports, protocols, and/or services to only those required, authorized, and approved to conduct official business or to address authorized quality of life issues. Database Management Systems using ports, protocols, and services deemed unsafe are open to attack through those ports, protocols, and services. This can allow unauthorized access to the database and through the database to other components of the information system. Satisfies: SRG-APP-000142-DB-000094, SRG-APP-000383-DB-000364

The DOD standard for authentication is DOD-approved public key infrastructure (PKI) certificates. Authentication based on user ID and password may be used only when it is not possible to employ a PKI certificate, and requires authorizing official approval. In such cases, database passwords stored in clear text, using reversible encryption or unsalted hashes, would be vulnerable to unauthorized disclosure. Database passwords must always be in the form of one-way, salted hashes when stored internally or externally to the database management system (DBMS).

Failure to a known secure state helps prevent a loss of confidentiality, integrity, or availability in the event of a failure of the information system or a component of the system. Preserving system state information helps to facilitate system restart and return to the operational mode of the organization with less disruption of mission/business processes. Aggregating log writes saves on performance but leaves a window for log data loss. The logging system inside VMware Postgres is capable of writing logs to disk fully and completely before the associated operation is returned to the client. This ensures database activity is always captured, even in the event of a system crash during or immediately after a given operation.

Database management systems typically separate security functionality from nonsecurity functionality via separate databases or schemas. Database objects or code implementing security functionality should not be commingled with objects or code implementing application logic. When security and nonsecurity functionality are commingled, users who have access to nonsecurity functionality may be able to access security functionality. VMware Postgres contains a number of system configuration schemas for which access must be strictly limited. By default, the "pg_catalog" and "information_schema" objects are configured to only be accessible in a read-only manner publicly and otherwise only accessible by the Postgres user. This configuration must be verified and maintained.

Any database management system (DBMS) or associated application providing too much information in error messages on the screen or printout risks compromising the data and security of the system. The structure and content of error messages must contain the minimal amount of information. Databases can inadvertently provide a wealth of information to an attacker through improperly handled error messages. In addition to sensitive business or personal information, database errors can provide host names, IP addresses, user names, and other system information not required for troubleshooting but very useful to someone targeting the system. Satisfies: SRG-APP-000266-DB-000162, SRG-APP-000267-DB-000163

Without the ability to centrally manage the content captured in the audit records, identification, troubleshooting, and correlation of suspicious behavior would be difficult and could lead to a delayed or incomplete analysis of an ongoing attack. The content captured in audit records must be managed from a central location (necessitating automation). Centralized management of audit records and logs provides for efficiency in maintenance and management of records, as well as the backup and archiving of those records. VMware Postgres is capable of outputting directly to syslog but for performance reasons, the vCenter Server Appliance (VCSA) is configured to ship logs centrally via "rsyslog" file monitoring. To facilitate that configuration, log files must be generated to disk. Satisfies: SRG-APP-000356-DB-000314, SRG-APP-000356-DB-000315, SRG-APP-000092-DB-000208, SRG-APP-000381-DB-000361, SRG-APP-000495-DB-000326, SRG-APP-000495-DB-000327, SRG-APP-000495-DB-000328, SRG-APP-000495-DB-000329, SRG-APP-000496-DB-000334, SRG-APP-000496-DB-000335, SRG-APP-000499-DB-000330, SRG-APP-000499-DB-000331, SRG-APP-000501-DB-000336, SRG-APP-000501-DB-000337, SRG-APP-000504-DB-000354, SRG-APP-000504-DB-000355, SRG-APP-000507-DB-000356, SRG-APP-000507-DB-000357, SRG-APP-000508-DB-000358

Without the ability to centrally manage the content captured in the audit records, identification, troubleshooting, and correlation of suspicious behavior would be difficult and could lead to a delayed or incomplete analysis of an ongoing attack. The content captured in audit records must be managed from a central location (necessitating automation). Centralized management of audit records and logs provides for efficiency in maintenance and management of records, as well as the backup and archiving of those records. For VMware Postgres logs to be successfully sent to a remote log management system, log events must be sent to "stderr". Those events will be captured and logged to disk where they will be picked up by "rsyslog" for shipping.

For performance reasons, "rsyslog" file monitoring is preferred over configuring VMware Postgres to send events to a "syslog" facility. Without ensuring that logs are created, that "rsyslog" configs are created, and that those configs are loaded, the log file monitoring and shipping will not be effective. Satisfies: SRG-APP-000359-DB-000319, SRG-APP-000360-DB-000320, SRG-APP-000515-DB-000318

If time stamps are not consistently applied and there is no common time reference, it is difficult to perform forensic analysis. Time stamps generated by VMware Postgres must include date and time expressed in UTC, a modern continuation of Greenwich Mean Time (GMT).