syscheck

Configuration options for file integrity monitoring:

alert_new_files

Specifies if FIM should alert when new files are created.

Default value

yes

Allowed values

yes, no

Example:

<alert_new_files>yes</alert_new_files>

Note

This setting is applied in the manager configuration, but it only takes effect on agents with versions lower than 3.12.

allow_remote_prefilter_cmd

Allows prefilter_cmd option apply in remote configuration (agent.conf).

Default value

no

Allowed values

yes, no

Example:

<allow_remote_prefilter_cmd>yes</allow_remote_prefilter_cmd>

Note

This option only can be activated from the agent side, on its own ossec.conf.

database

Specifies where the database is going to be stored.

Default value

disk

Allowed values

disk, memory

directories

List of directories to be monitored. The directories can be comma-separated or multiple lines may be entered to include multiple directories.

All files and subdirectories within the noted directories will also be monitored.

Drive letters without directories are valid. It's possible to configure them by removing the last backslash, for example D:.

This is to be set on the system to be monitored (or in the agent.conf, if appropriate).

There is a limit of 64 directories, comma-separated, that can be written in one line .

Wildcard characters (? and *) can be used to monitor paths that fulfill the given pattern. These wildcards will be reloaded every time a scheduled scan is run.

Default value

/etc,/usr/bin,/usr/sbin,/bin,/sbin

Allowed values

Any directory

Any environment variable

Attributes:

realtime

This will enable real-time/continuous monitoring on Linux (using the inotify system calls) and Windows systems.

Real time only works with directories, not individual files.

Default value

no

Allowed values

yes, no

whodata

This will enable who-data monitoring on Linux and Windows systems.

Default value

no

Allowed values

yes, no

report_changes

Report file changes. This is limited to text files at this time.

Default value

no

Allowed values

yes, no

diff_size_limit

Limit the maximum size of the file which will report diff information with report_changes enabled.

Files bigger than this value will not report diff information.

Default value

50MB

Allowed values

Any positive number followed by KB/MB/GB

check_all

It modifies the value of all attributes with the prefix check_.

Default value

yes

Allowed values

yes, no

check_sum

Check the MD5, SHA-1 and SHA-256 hashes of the files.

Same as using check_md5sum="yes", check_sha1sum="yes" and check_sha256sum="yes" at the same time.

Default value

yes

Allowed values

yes, no

check_sha1sum

Check only the SHA-1 hash of the files.

Default value

yes

Allowed values

yes, no

check_md5sum

Check only the MD5 hash of the files.

Default value

yes

Allowed values

yes, no

check_sha256sum

Check only the SHA-256 hash of the files.

Default value

yes

Allowed values

yes, no

check_size

Check the size of the files.

Default value

yes

Allowed values

yes, no

check_owner

Check the owner of the files.

On Windows, uid will always be 0.

Default value

yes

Allowed values

yes, no

check_group

Check the group owner of the files/directories.

Available for UNIX. On Windows, gid will always be 0 and the group name will be blank.

Default value

yes

Allowed values

yes, no

check_perm

Check the permission of the files/directories.

On Windows, a list of denied and allowed permissions will be given for each user or group since version 3.8.0.

Only works on NTFS partitions on Windows systems.

Default value

yes

Allowed values

yes, no

check_attrs

Check the attributes of the files. Available for Windows.

Default value

yes

Allowed values

yes, no

check_mtime

Check the modification time of a file.

Default value

yes

Allowed values

yes, no

check_inode

Check the file inode. Available for UNIX. On Windows, inode will always be 0.

Default value

yes

Allowed values

yes, no

restrict

Limit checks to files containing the entered string in the file name.

Any directory or file path is allowed.

Default value

N/A

Allowed value

sregex

tags

Add tags to alerts for monitored directories.

Default value

N/A

Allowed values

Tags list separated by commas

recursion_level

Limits the maximum level of recursion allowed.

Default value

256

Allowed values

Any integer between 0 and 320

follow_symbolic_link

The setting is available for UNIX systems and only applies when a symbolic link is set in the configuration directly.

When this flag is enabled, the link is followed and its content is monitored. Otherwise, the own link is monitored.

Default value

no

Allowed values

yes, no

When there is a conflict between options that modify the same attribute, the last one configured overrides. For instance:

<directories check_all="no" check_sha256="yes">/etc</directories>

The configuration above, set the option check_sha256 to YES.

<directories check_sha256="yes" check_all="no">/etc</directories>

Nevertheless, the second one disables the SHA-256 hash check.

If there is a conflict between a block with wildcards and another without them, the block without wildcards will be used for the specific case. As an example:

<directories>C:\Users\*\Downloads</directories>

The above block will set the Downloads folder of all users to be monitored in scheduled mode.

<directories realtime="yes">C:\Users\vagrant\Downloads</directories>

Even though the above block is included in the previous one, C:\Users\vagrant\Downloads will be monitored in real time because it has no wildcards.

disabled

Indicates if the syscheck scan is disabled or not.

Default value

no

Allowed values

yes, no

Example:

<disabled>no</disabled>

frequency

Frequency that the syscheck will be run. Given in seconds.

Default value

43200

Allowed values

A positive number, time in seconds.

Example:

<frequency>43200</frequency>

ignore

List of files or directories to be ignored. Introduced as one entry per line. Multiple lines may be entered to include multiple files or directories. Ignored files and directories are still scanned, but the results are not reported.

Default value

The default configuration may vary depending on the operating system.

Allowed values

Any directory or file name.

Attributes:

type

This is a simple regex pattern to filter out files, so alerts are not generated.

Allowed values

sregex

Example:

<ignore>/etc/mtab</ignore>
<ignore type="sregex">.log$|.swp$</ignore>

max_eps

Sets the maximum event reporting throughput. Events are messages that will produce an alert.

Default value

50

Allowed values

Integer number between 0 and 1000000. 0 means disabled.

Example:

<max_eps>50</max_eps>

max_files_per_second

Sets the maximum number of files scanned per second. If this option is set to 0, there will be no limit on the number of files scanned per second.

Default value

0

Allowed values

Integer positive number. 0 means no limit.

Example:

<max_files_per_second>100</max_files_per_second>

prefilter_cmd

Run to prevent prelinking from creating false positives.

Default value

n/a

Allowed values

Command to prevent prelinking.

Example:

<prefilter_cmd>/usr/sbin/prelink -y</prefilter_cmd>

Note

This option may negatively impact performance as the configured command will be run for each file checked.

Note

This option is ignored when defined at agent.conf if allow_remote_prefilter_cmd is set to no at ossec.conf.

process_priority

Sets the nice value for Syscheck process.

Default value

10

Allowed values

Integer number between -20 and 19.

The "niceness" scale in Linux goes from -20 to 19, whereas -20 is the highest priority and 19 the lowest priority.

For Windows the scale is translated as described in the following table:

-20 to -10

THREAD_PRIORITY_HIGHEST

-9 to -5

THREAD_PRIORITY_ABOVE_NORMAL

-4 to 0

THREAD_PRIORITY_NORMAL

1 to 5

THREAD_PRIORITY_BELOW_NORMAL

6 to 10

THREAD_PRIORITY_LOWEST

11 to 19

THREAD_PRIORITY_IDLE

Example:

<process_priority>10</process_priority>

registry_ignore

List of registry entries to be ignored. One entry per line. Multiple lines may be entered to include multiple registry entries.

Default value

The default configuration may vary depending on the operating system.

Allowed values

Any registry entry.

Attributes:

arch

Select the Registry to ignore depending on the architecture.

Default value

32bit

Allowed values

32bit, 64bit, both

type

This is a simple regex pattern to filter out files so alerts are not generated.

Allowed values

sregex

Example:

<registry_ignore>HKEY_LOCAL_MACHINE\Security\Policy\Secrets</registry_ignore>
<registry_ignore type="sregex">\Enum$</registry_ignore>

scan_day

Day of the week to run the scans, one entry per line.

Default value

n/a

Allowed values

Day of the week.

Example:

<scan_day>thursday</scan_day>

scan_time

Time to run the scans. Times may be represented as 9pm or 8:30.

Default value

n/a

Allowed values

Time of day.

Example:

<scan_time>8:30</scan_time>

Note

This may delay the initialization of real-time scans.

skip_dev

Specifies if syscheck should scan the /dev directory. This option works on Linux and FreeBSD systems.

Default value

yes

Allowed values

yes, no

Example:

<skip_dev>yes</skip_dev>

skip_nfs

Specifies if syscheck should scan network mounted filesystems. This option works on Linux and FreeBSD systems. Currently, skip_nfs will exclude checking files on CIFS or NFS mounts.

Default value

yes

Allowed values

yes, no

Example:

<skip_nfs>yes</skip_nfs>

skip_proc

Specifies if syscheck should scan the /proc directory. This option works on Linux and FreeBSD systems.

Default value

yes

Allowed values

yes, no

Example:

<skip_proc>yes</skip_proc>

skip_sys

Specifies if syscheck should scan the /sys directory. This option works on Linux systems.

Default value

yes

Allowed values

yes, no

Example:

<skip_sys>yes</skip_sys>

file_limit

Specifies a limit on the number of files that FIM monitors. It ignores files added once the database reached the limit.

<!-- Maximum number of files to be monitored -->
<file_limit>
  <enabled>yes</enabled>
  <entries>100000</entries>
</file_limit>

enabled

Specifies if the number of monitored entries has a limit.

Default value

yes

Allowed values

yes/no

entries

Specifies the maximum number of files to monitor.

Default value

100000

Allowed values

Integer number between 1 and 2147483647.

registry_limit

Note

This section only applies to Windows agents.

Specifies a limit on the number of registry entries that FIM monitors. It ignores registry values created once the database reached the limit.

<!-- Maximum number of registries to be monitored -->
<registry_limit>
  <enabled>yes</enabled>
  <entries>100000</entries>
</registry_limit>

enabled

Specifies if the number of monitored entries has a limit.

Default value

yes

Allowed values

yes/no

entries

Specifies the maximum number of registry entries to monitor.

Default value

100000

Allowed values

Integer number between 1 and 2147483647.

synchronization

The database synchronization settings are configured inside this tag.

<!-- Database synchronization settings -->
<synchronization>
  <enabled>yes</enabled>
  <interval>5m</interval>
  <max_interval>1h</max_interval>
  <response_timeout>30</response_timeout>
  <queue_size>16384</queue_size>
  <thread_pool>1</thread_pool>
  <max_eps>10</max_eps>
</synchronization>

enabled

Specifies performing periodic inventory synchronizations.

Default value

yes

Allowed values

yes/no

registry_enabled

On Windows agents, enables inventory synchronizations for registry entries. If enabled is set to no, this parameter is ignored.

Default value

yes

Allowed values

yes/no

interval

Specifies the initial time interval between every inventory synchronization. If the synchronization fails the value is duplicated until it reaches the value of max_interval. If the synchronization succeds the value is restored.

Default value

5 m

Allowed values

Any number greater than or equal to 0. Allowed suffixes (s, m, h, d).

max_interval

Maximum time interval to trigger a synchronization. When a synchronization fails the interval is duplicated up to this maximum value.

Default value

1 h

Allowed values

Any integer greater than or equal to interval. Allowed suffixes (s, m, h, d).

response_timeout

Waiting time in seconds since a sync message is sent or received for the next synchronization activity. If the agent doesn't send or receive a message in this interval the synchronization is marked as successful. If a synchronization is unsuccessful, the synchronization interval is doubled up to the max_interval value. This mechanism avoids synchronization overlapping.

Default value

30

Allowed values

Any number between 0 and interval.

queue_size

Specifies the queue size of the manager synchronization responses.

Default value

16384

Allowed values

Integer number between 2 and 1000000.

thread_pool

Specifies the number of threads that FIM database synchronization uses. FIM uses the lesser value of the configured value and the number of system CPU cores.

Default value

1

Allowed values

Any integer greater than 0.

max_eps

Sets the maximum synchronization message throughput.

Default value

10

Allowed values

Integer number between 0 and 1000000. 0 means disabled.

diff

The diff settings will be configured inside this tag.

<diff>
  <disk_quota>
    <enabled>yes</enabled>
    <limit>1GB</limit>
  </disk_quota>
  <file_size>
    <enabled>yes</enabled>
    <limit>50MB</limit>
  </file_size>

  <nodiff>/etc/ssl/private.key</nodiff>
</diff>

disk_quota

This option can be used to limit the size of the queue/diff/local folder where ThreatLockDown stores the compressed files used to perform the diff operation when report_changes is enabled. After reaching this size, alerts will not show the diff information until the size is smaller than the configured limit.

enabled

Set the disk quota limit option to enabled or disabled.

Default value

yes

Allowed values

yes/no

limit

Specifies the limit for the size of the queue/diff/local folder.

Default value

1GB

Allowed values

Any positive number followed by KB/MB/GB

file_size

This option can be used to limit the size of the file which will report diff information with report_changes enabled. Files bigger than this limit will not report diff information until the size is smaller than the configured limit again.

enabled

Set the size limit of a file to enabled or disabled.

Default value

yes

Allowed values

yes/no

limit

Specifies the limit for the size of files monitored with report_changes.

Default value

50MB

Allowed values

Any positive number followed by KB/MB/GB

nodiff

List of files to not compute the diff (one entry per line). It could be used for sensitive files like a private key, credentials stored in a file, or database configuration, avoiding data leaking by sending the file content changes through alerts.

Allowed values

Any file name.

Example

/etc/ssl/private.key

Attributes:

type

This is a simple regex pattern to filter out files so alerts are not generated.

Allowed values

sregex

registry_nodiff

List of values to not compute the diff (one entry per line).

Allowed values

Any registry path, with value_name added.

Example

HKEY_LOCAL_MACHINE\SOFTWARE\test_key\value_name

Attributes:

type

This is a simple regex pattern to filter out files so alerts are not generated.

Allowed values

sregex

whodata

The Whodata options will be configured inside this tag.

<!-- Whodata options -->
<whodata>
    <restart_audit>yes</restart_audit>
    <audit_key>auditkey1,auditkey2</audit_key>
    <startup_healthcheck>yes</startup_healthcheck>
    <queue_size>100000</queue_size>
</whodata>

restart_audit

Allows the system to restart Auditd after installing the plugin. Note that by setting this field to no the new whodata rules won't be applied automatically.

Default value

yes

Allowed values

yes, no

audit_key

Sets up the FIM engine to collect the Audit events using keys with audit_key. ThreatLockDown will include in its FIM baseline those events being monitored by Audit using audit_key. For those systems where Audit is already set to monitor folders for other purposes, ThreatLockDown can collect events generated as a key from audit_key. This option is only available for Linux systems with Audit.

Default value

Empty

Allowed values

Any string separated by commas

Note

Audit allow inserting spaces inside the keys, so the spaces inserted inside the field <audit_key> will be part of the key.

startup_healthcheck

Allows disabling the Audit health check during the Whodata engine starting. This option is only available for Linux systems with Audit.

Default value

yes

Allowed values

yes, no

Warning

The health check ensures that the rules required by Whodata can be set in Audit correctly and also that the generated events can be obtained. Disabling the health check may cause functioning problems in Whodata and loss of FIM events.

queue_size

Sets the maximum capacity of the queue that stores the audit dispatcher events. This option applies to Linux systems with Audit.

Default value

16384

Allowed values

Any number from 10 to 1048576

Warning

If the queue fills up, some audit events may be lost. However, the next scheduled scan will generate the missing alerts without the audit information.

For more information, please read auditing who-data

windows_audit_interval

Sets the frequency in seconds with which the Windows agent checks that the Local Audit Policies and the SACLs of the directories monitored in whodata mode are correct.

Default value

300 seconds

Allowed values

Any number from 1 to 9999

Example:

<windows_audit_interval>300</windows_audit_interval>

windows_registry

List of registry entries to be monitored. One entry per line. Multiple lines may be entered to include multiple registry entries.

New in version 4.6.0: To scan paths matching a pattern, you can use the wildcard characters ? and *. For example HKEY_LOCAL_MACHINE\SOFTWARE\*. FIM uses these wildcards during scheduled scan.

Default value

The default configuration may vary depending on the operating system.

Allowed values

Any registry entry.

Attributes:

arch

Select the Registry view depending on the architecture.

Default value

32bit

Allowed values

32bit, 64bit, both

tags

Add tags to alerts for monitored registry entries.

Allowed values

Tags list separated by commas

report_changes

Report registry value changes. This is limited to REG_SZ, REG_MULTI_SZ, REG_DWORD, REG_DWORD_BIG_ENDIAN,

REG_QWORD value.

Default value

no

Allowed values

yes, no

diff_size_limit

Limit the maximum size of the value which will report diff information with report_changes enabled.

Values bigger than this size will not report diff information.

Default value

50MB

Allowed values

Any positive number followed by KB/MB/GB

check_all

It modifies the value of all attributes with the prefix check_.

Default value

yes

Allowed values

yes, no

check_sum

Check the MD5, SHA-1 and SHA-256 hashes of the registry.

Same as using check_md5sum="yes", check_sha1sum="yes" and check_sha256sum="yes" at the same time.

Default value

yes

Allowed values

yes, no

check_sha1sum

Check only the SHA-1 hash of the registries.

Default value

yes

Allowed values

yes, no

check_md5sum

Check only the MD5 hash of the registries.

Default value

yes

Allowed values

yes, no

check_sha256sum

Check only the SHA-256 hash of the registries.

Default value

yes

Allowed values

yes, no

check_size

Check the size of the registries.

Default value

yes

Allowed values

yes, no

check_owner

Check the owner of the registries.

Default value

yes

Allowed values

yes, no

check_group

Check the group owner of the registries.

Just gid will be checked, group name will be blank.

Default value

yes

Allowed values

yes, no

check_perm

Check the permission of the registries.

A list of denied and allowed permissions will be given for each user or group.

Default value

yes

Allowed values

yes, no

check_mtime

Check the modification time of a registry.

Default value

yes

Allowed values

yes, no

check_type

Check the type of a value. It is used to notify changes in the values of the monitored registry.

This is limited to REG_NONE, REG_SZ, REG_EXPAND_SZ, REG_BINARY, REG_DWORD, REG_DWORD_BIG_ENDIAN, REG_LINK,

REG_MULTI_SZ, REG_RESOURCE_LIST, REG_FULL_RESOURCE_DESCRIPTOR, REG_RESOURCE_REQUIREMENTS_LIST, REG_QWORD.

Default value

yes

Allowed values

yes, no

restrict_key

Limit checks to registries containing the entered sregex in the registry name.

Any registry is allowed.

Default value

N/A

Allowed value

sregex

restrict_value

Limit checks to registry values containing the entered sregex in the value name.

Any registry value is allowed.

Default value

N/A

Allowed value

sregex

recursion_level

Limits the maximum level of recursion allowed.

Default value

512

Allowed values

Any integer between 0 and 512

Example:

<windows_registry arch="both">HKEY_LOCAL_MACHINE\Software\Classes\Protocols</windows_registry>
<windows_registry arch="both" restrict_value="^some_value_name$">HKEY_LOCAL_MACHINE\Software\Policies</windows_registry>
<windows_registry tags="services-registry">HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services</windows_registry>
<windows_registry arch="both" check_sum="no">HKEY_LOCAL_MACHINE\SOFTWARE\test_key</windows_registry>
<windows_registry arch="64bit" recursion_level="3">HKEY_LOCAL_MACHINE\SYSTEM\Setup</windows_registry>

New in version 4.6.0.

Configurations with specific registry keys take precedence over those that use wildcards. The following configuration block provides an example. The first settings line enables scanning the SOFTWARE keys of all users without checking any hashes.

<windows_registry arch="both" check_sum="no">HKEY_LOCAL_MACHINE\SOFTWARE\*</windows_registry>
<windows_registry arch="both" check_sum="yes">HKEY_LOCAL_MACHINE\SOFTWARE\TEST_KEY</windows_registry>

However, the second line does enable hash checking for TEST_KEY. This is a specific key and this setting takes precedence here.

<windows_registry arch="both" check_sum="no">HKEY_LOCAL_MACHINE\SOFTWARE\*</windows_registry>
<windows_registry arch="both" check_sum="yes">HKEY_LOCAL_MACHINE\SOFTWARE\TEST_KEY</windows_registry>

Default syscheck configuration:

<!-- File integrity monitoring -->
<syscheck>
 <disabled>no</disabled>
 <!-- Frequency that syscheck is executed default every 12 hours -->
 <frequency>43200</frequency>
 <scan_on_start>yes</scan_on_start>
 <!-- Generate alert when new file detected -->
 <alert_new_files>yes</alert_new_files>
 <!-- Don't ignore files that change more than 'frequency' times -->
 <auto_ignore frequency="10" timeframe="3600">no</auto_ignore>
 <!-- Directories to check  (perform all possible verifications) -->
 <directories>/etc,/usr/bin,/usr/sbin</directories>
 <directories>/bin,/sbin,/boot</directories>
 <!-- Files/directories to ignore -->
 <ignore>/etc/mtab</ignore>
 <ignore>/etc/hosts.deny</ignore>
 <ignore>/etc/mail/statistics</ignore>
 <ignore>/etc/random-seed</ignore>
 <ignore>/etc/random.seed</ignore>
 <ignore>/etc/adjtime</ignore>
 <ignore>/etc/httpd/logs</ignore>
 <ignore>/etc/utmpx</ignore>
 <ignore>/etc/wtmpx</ignore>
 <ignore>/etc/cups/certs</ignore>
 <ignore>/etc/dumpdates</ignore>
 <ignore>/etc/svc/volatile</ignore>
 <!-- File types to ignore -->
 <ignore type="sregex">.log$|.swp$</ignore>
 <!-- Check the file, but never compute the diff -->
 <nodiff>/etc/ssl/private.key</nodiff>
 <skip_nfs>yes</skip_nfs>
 <skip_dev>yes</skip_dev>
 <skip_proc>yes</skip_proc>
 <skip_sys>yes</skip_sys>
 <!-- Nice value for Syscheck process -->
 <process_priority>10</process_priority>
 <!-- Maximum output throughput -->
 <max_eps>50</max_eps>
 <!-- Database synchronization settings -->
 <synchronization>
   <enabled>yes</enabled>
   <interval>5m</interval>
   <max_eps>10</max_eps>
 </synchronization>
</syscheck>