Matcher (matcher)

A matcher entity is a field that is parsed, for example, EventName, and is paired with the appropriate pattern and group for parsing.

Matchers have an associated order. If multiple matchers are specified for the same field name, the matchers are run in the order that is presented until a successful parse is found or a failure occurs.

Table 1. Description of matcher parameters
Parameter Description

field (Required)

The field to which you want the pattern to apply, for example, EventName, or SourceIp. You can use any of the field names that are listed in the List of valid matcher field names table.

pattern-id (Required)

The pattern that you want to use when the field is parsed from the payload. This value must match (including case) the ID parameter of the pattern that is previously defined in a pattern ID parameter (Table 1).

order (Required)

The order that you want this pattern to attempt among matchers that are assigned to the same field. If two matchers are assigned to the EventName field, the one with the lowest order is attempted first.

capture-group (Optional)

Referenced in the regular expression inside parenthesis ( ). These captures are indexed starting at one and processed from left to right in the pattern. The capture-group field must be a positive integer less than or equal to the number of capture groups that are contained in the pattern. The default value is zero, which is the entire match.

For example, you can define a single pattern for a source IP address and port; where the SourceIp matcher can use a capture group of 1, and the SourcePort matcher can use a capture group of 2, but only one pattern needs to be defined.

This field has a dual purpose when combined with the enable-substitutions parameter.

To see an example, review the extension document example.

enable-substitutions (Optional)

Boolean

When you set to true, a field cannot be adequately represented with a straight group capture. You can combine multiple groups with extra text to form a value.

This parameter changes the meaning of the capture-group parameter. The capture-group parameter creates the new value, and group substitutions are specified by using \x where x is a group number, 1 - 9. You can use groups multiple times, and any free-form text can also be inserted into the value. For example, to form a value out of group 1, followed by an underscore, followed by group 2, an @, and then group 1 again, the appropriate capture-group syntax is shown in the following code:

capture-group=”\1_\2@\1”

In another example, a MAC address is separated by colons, but in QRadar®, MAC addresses are usually hyphen-separated. The syntax to parse and capture the individual portions is shown in the following example:

capture-group=”\1:\2:\3:\4:\5:\6”

If no groups are specified in the capture-group when substitutions are enabled, a direct text replacement occurs.

Default is false.

ext-data (Optional)

An extra-data parameter that defines any extra field information or formatting that a matcher field can provide in the extension.

The only field that currently uses this parameter is DeviceTime.

For example, you might have a device that sends events by using a unique time stamp, but you want the event to be reformatted to a standard device time. Use the ext-data parameter included with the DeviceTime field to reformat the date and time stamp of the event. For more information, see the List of valid matcher field names.

The following table lists valid matcher field names.

Table 2. List of valid matcher field names
Field name Description

EventName (Required)

The event name to be retrieved from the QID to identify the event.

Note: This parameter doesn't appear as a field in the Log Activity tab.

EventCategory

cat (LEEF)

An event category for any event with a category not handled by an event-match-single entity or an event-match-multiple entity.

Combined with EventName, EventCategory is used to search for the event in the QID. The fields that are used for QIDmap lookups require an override flag to be set when the devices are already known to QRadar, for example, 
<event-match-single event-name=
"Successfully logged in" 
force-qidmap-lookup-on-fixup="true" 
device-event-category="CiscoNAC" 
severity="4" send-identity=
"OverrideAndNeverSend" />
The force-qidmap-lookup-on-fixup="true" is the flag override.
Note: This parameter doesn't appear as a field in the Log Activity tab.

SourceIp

src (LEEF)

The source IP address for the message.

SourcePort

srcPort (LEEF)

The source port for the message.

SourceIpPreNAT

srcPreNAT (LEEF)

The source IP address for the message before Network Address Translation (NAT) occurs.

SourceIpPostNAT

srcPostNAT (LEEF)

The source IP address for the message after NAT occurs.

SourceMAC

srcMAC (LEEF)

The source MAC address for the message.

SourcePortPreNAT

srcPreNATPort (LEEF)

The source port for the message before NAT occurs.

SourcePortPostNAT

srcPostNATPort (LEEF)

The source port for the message after NAT occurs.

DestinationIp

dst (LEEF)

The destination IP address for the message.

DestinationPort

dstPort (LEEF)

The destination port for the message.

DestinationIpPreNAT

dstPreNAT (LEEF)

The destination IP address for the message before NAT occurs.

DestinationIpPostNAT

dstPostNAT (LEEF)

The destination IP address for the message after NAT occurs.

DestinationPortPreNAT

dstPreNATPort (LEEF)

The destination port for the message before NAT occurs.

DestinationPortPostNAT

dstPostNATPort (LEEF)

The destination port for the message after NAT occurs.

DestinationMAC

dstMAC (LEEF)

The destination MAC address for the message.

DeviceTime

devTime (LEEF)

The time and format that is used by the device. This date and time stamp represent the time that the event was sent, according to the device. This parameter doesn't represent the time that the event arrived. The DeviceTime field supports the ability to use a custom date and time stamp for the event by using the ext-data Matcher attribute.

The following list contains examples of date and time stamp formats that you can use in the DeviceTime field:

  • ext-data="dd/MMM/YYYY:hh:mm:ss"

    11/Mar/2015:05:26:00

  • ext-data="MMM dd YYYY / hh:mm:ss"

    Mar 11 2015 / 05:26:00

  • ext-data="hh:mm:ss:dd/MMM/YYYY"

    05:26:00:11/Mar/2015

For more information about the possible values for the data and time stamp format, see the Joda-Time web page (http://www.joda.org/joda-time/key_format.html).

DeviceTime is the only event field that uses the ext-data optional parameter.

Protocol

proto (LEEF)

The protocol for the message; for example, TCP, UDP, or ICMP.

UserName

The user name for the message.

HostName

identHostName (LEEF)

The host name for the message. Typically, this field is associated with identity events.

GroupName

identGrpName (LEEF)

The group name for the message. Typically, this field is associated with identity events.

IdentityIp

The identity IP address for the message.

IdentityMac

identMAC (LEEF)

The identity MAC address for the message.

IdentityIpv6

The IPv6 identity IP address for the message.

NetBIOSName

identNetBios (LEEF)

The NetBIOS name for the message. Typically, this field is associated with identity events.

ExtraIdentityData

Any user-specific data for the message. Typically, this field is associated with identity events.

SourceIpv6

The IPv6 source IP address for the message.

DestinationIpv6

The IPv6 destination IP address for the message.