Modifying Detections with Inline Filters
Modify an existing rule without writing code
Inline filters are in open beta as of Panther version 1.54. Please share any bug reports and feature requests with your account team.
You can easily tune existing rules, including Panther-managed rules, by adding Inline Filters. An Inline Filter is a condition that must pass in order for the detection logic to then be run.
In the Panther Console, you can create Inline Filters using a no-code builder. In the CLI workflow, you can create Inline Filters by adding the
InlineFilters YAML key. Note that Inline Filters are available only on rules, not scheduled rules nor policies.A common use case for filters is to add an allowlist or denylist.
Filter statements are evaluated before a detection's logic. A filter must return
true (i.e., match the event) for the detection logic itself to then be run. In both the Console and CLI workflow, filters can be grouped using
AND or OR logic. If an event does not contain the field the filter is evaluating, the filter will pass. If the field the filter is evaluating has a value of
none, the filter will return false on positive comparators or on comparators that don't apply, and true for inverse comparators.In the Console, filters are not available during new rule creation. In the CLI workflow, you can include
InlineFilters on new rules.While it is broadly discouraged to manage detection content using both CLI workflows and the Console simultaneously, it is possible to use Inline Filters in the Console alongside the CLI workflow. Filters created in the Console will not be overwritten or deleted when an update to detection content is made in the CLI workflow.
You can add filters to a rule from its edit page, or within an alert triggered by that rule.
From a rule's edit page
From an alert event
- 1.In the left-hand navigation bar of your Panther Console, click Build > Detections.
- 2.In the list of detections, click a rule's name to view its details page.
- 3.Within the Detect section, under Filter to only include events: and to the right of Where, click +.
- In the menu that appears, select either Add Filter or Add Filter Group.
- 4.For each filter (either on its own or within a group), define the logic:
- 1.Click Key, then select an event key the condition will apply to.
- 2.Click Condition, then select a condition.
- 3.If the selected Condition requires an inputted value(s) (e.g.,
isorcontains), provide a value or list of values.
- 5.Between each filter and filter group, ensure the correct combinator (either and or or) is selected.
- 6.Run unit tests to ensure they pass with the added filter(s).
- 7.In the upper-right corner of the page, click Deploy to save your changes.
You can add Inline Filters to a rule directly from an event in an associated alert. This is particularly helpful if you've received a false positive alert, and want to tune the triggered detection so it won't match on similar events in the future.
- 1.In the left-hand navigation bar of your Panther Console, click Alerts.
- 2.Locate the alert whose associated rule you'd like to tune, and click its name.
- 3.On the alert's detail page, scroll down to the Event section.
- 4.In the event's JSON, hover over the indicator you'd like the new filter to target, and click the target icon.
- The Add Filter slide-out panel will open on the right-hand side of the window.
- 5.In the Add Filter slide-out panel, a new filter will be pre-populated in the following way:
- Key: defaults to the field on which you clicked the target icon in the event JSON.
- Condition: defaults to is not, assuming you would not like to receive alerts for events like this in the future.
- String: defaults to the value of the selected field in the event JSON.
- 6.Make any desired changes to the filter. All pre-populated fields (i.e., Key, Condition and String) are editable.
- 7.Locate the Unit Test section near the bottom of the panel. If the rule is not Panther-managed and you'd like to create a new unit test for the rule using the current event, click the checkbox labeled Add the current alert event as a unit test.
- The toggle labeled The detection should trigger based on the example event is editable. It defaults to No, as you are likely trying to prevent alerts like this in the future.
- 8.Click Save & Run Test.
- This runs all of the target rule's unit tests. If you created a new unit test in step 7, it is also run.
- In order for the new filter(s) to be saved, all of the rule's unit tests must pass. If any of the unit tests fail:
- If the rule is not Panther-managed, click View Detection to be taken to the rule's detail page to edit unit tests. From there, you can click Update to save your changes to the rule.
- If the rule is Panther-managed, its unit tests are read-only, meaning you can't alter failing tests to make them pass. To be able to add the filter successfully, instead follow the Working with failed unit tests with filters workflow.
If the Rule Filter operator you've selected requires the value field to take in an array (such as the
is in operator), you'll input the array values in a modal that pops up when you click into the value field.To add values to an array:
- 1.After selecting a Key and Condition for your Filter, click into the values field.
- This will open the array input modal.
- 2.In the modal, enter the array value(s) in the input field.
- If your input is comma-delimited, check the Values entered above are comma-delimited checkbox.
- When this field is checked, the text inputted into the values field will be separated (using a comma delimiter) into multiple values. For example, entering "User 1,User 2,User 3" will result in three values added.
- If your input is not comma-delimited, leave Values entered above are comma-delimited unchecked.
- When this field is unchecked, you can add values that contain commas one at a time. For example, entering "1,000" will add just one value.
- 3.Click Add.
- 4.Repeat steps 2-3 as needed, until all values have been added to the array.
- 5.Click Apply.
Like the filters created in the Console, YAML filters are evaluated before the detection logic of a rule. If the filter returns
true, the detection logic will be executed. If the filter returns false, the evaluation of the detection will stop, and the detection will return false altogether.A YAML filter is denoted by the
InlineFilters key. Within InlineFilters, list one or more match expressions. See YAML Match Expression Reference to learn how to construct different types of match expressions.Example:
InlineFilters:
- Key: environment
Condition: StartsWith
Value: "Sandbox"
Some match expression functionality described in YAML Match Expression Reference is not possible in
InlineFilters. These limitations include:InlineFilterscannot be used on scheduled rules or policies, only rules.EqualsDoesNotEqualIsGreaterThanIsGreaterThanOrEqualsIsLessThanIsLessThanOrEqualsContainsDoesNotContainStartsWithEndsWithIsIPAddressInCIDRIsIPAddressNotInCIDRCIDRContainsIPAddressesCIDRDoesNotContainIPAddressesIsInIsNotInIsIPAddressPublicIsIPAddressPrivateIsNullOrEmptyIsNotNullOrEmpty
To create an Inline Filter in the CLI workflow in either a Python or YAML rule, in the detection's YAML file, include the
InlineFilters key. Within InlineFilters should be one or more match expressions.For Panther-managed rules with filters, you currently cannot add or edit unit tests. You cannot save a rule if the unit test does not pass.
If a unit test fails, take the following steps:
- 1.Clone the Panther-managed rule.
- 2.Add your filter(s) to the cloned rule.
- 3.Edit the unit tests for the cloned rule so that they pass.
Refer to the below operators and value types when building out your filters in the Console.
Operation | Usage guidelines | Supported field types | Examples |
|---|---|---|---|
is / is not | Valid for a single value. Results include only events where the field matches/ does not match the value in the filter. | string, ip, bool, int | username is “root” |
is in / is not in | Valid for multiple values. Results include only events where the field matches/does not match an entry in the list of values in the filter. | string, int | username is in [ “root”, “admin” ]
port is in [25, 553] |
is empty | Valid for an event where the field's value is not specified. The operator tests only for the absence of data. | string, int array, ip array, float array, bool array, string array | errors_list is empty |
is not empty | Valid for an event where the field's value is specified. The operator tests only for the presence of data. | string, int array, ip array, float array, bool array, string array | errors_list is not empty |
contains | Valid for an event that contains a specific single value or multiple values. Results include only events where at least one of the values is in the filter. | string, int array, ip array, bool array, string array | domain contains “.google.com”
p_any_port contains 22 |
does not contain | Valid for events that contain a specific single value or multiple values. Results include only events that do not contain any of the values in the filter. | string, int array, ip array, bool array, string array | domain !contains “.google.com”
p_any_port !contains 22 |
starts with | Valid for events that begin with a value. | string | role starts with “admin_” |
ends with | Valid for events that end with a value. | string | domain ends with “.cc” |
is greater than | Valid for a single value. Results include only events where the field is greater than the value in the filter. | int, float | port > 1023 |
is less than | Valid for a single value. Results include only events where the field is less than the value in the filter. | int, float | port < 1024 |
is greater than or equal | Valid for a single value. Results include only events where the field is greater than or equal to the value in the filter. | int | count ≥ 1 |
is less than or equal | Valid for a single value. Results include only events where the field is less than or equal to the value in the filter. | int | count ≤ 100 |
is private | Valid for private IPs | IP | dst_ip is_private |
is public | Valid for public IPs | IP | src_ip is_public |
is in CIDR / is not in CIDR | Valid for addresses within a CIDR (Classless Inter-Domain Routing) block. Results include only events where the field is/is not in the CIDR block in the filter. | IP | src_ip in_cidr 192.168.0.0/16 |
does not contain IP in CIDR | Valid for an array of IPs that does not contain any IP address within a CIDR block. Results include only events where the field does not contain any IP address within the CIDR block in the filter. | ip array | p_any_ip_address !contains_ip 8.8.0.0/16
p_any_ip_address !contains_ip 1.1.1.1/32 |
contains IP in CIDR | Valid for an array of IPs containing any IP address within a CIDR block. Results include only events where the field contains at least one IP address within the CIDR block in the filter. | ip array | p_any_ip_address contains_ip 8.8.0.0/16
p_any_ip_address contains_ip 1.1.1.1/32 |
Value types | Description |
|---|---|
string | A string value |
int | A 32-bit integer number in the range -2147483648, 2147483647 |
float | A 64-bit floating point number |
boolean | A boolean value true / false |
array | A JSON array where each element is of the same type |
ip | A single valid IPv4 or IPv6 address |
CIDR | A classless inter-domain routing block |
Last modified 24d ago