...
Now that we know what we should do, the next question is how to accomplish it; in other words, we must define what exactly we mean when we say "severity." The capability as implemented in Metron is accomplished by providing the ability to associate possibly complex conditions to numeric scores. Then, for each message, the set of conditions are evaluated and the set of numbers for matching conditions are aggregated via a configurable aggregation function. This aggregated score is added to the message in the threat.triage.level
. Let's dig a bit deeper into this and provide an example.
...
Stellar Language
The heart of the problem is how one defines a "condition." In Metron, we provide a custom domain specific language named "Stellar" for defining conditions.
The query language supports the following:
- Referencing fields in the enriched JSON
- Simple boolean operations:
and, &&
not
or, ||
- Determining whether a field exists (via
exists
) - The ability to have parenthesis to make order of operations explicit
- A fixed set of functions which take strings and return boolean. Currently:
IN_SUBNET(ip, cidr1, cidr2, ...)
IS_EMPTY(str)
STARTS_WITH(str, prefix)
ENDS_WITH(str, suffix)
REGEXP_MATCH(str, pattern)
- A fixed set of string to string transformation functions. Currently:
TO_LOWER
TO_UPPER
TRIM
The documentation can be found here - https://github.com/apache/incubator-metron/blob/master/metron-platform/metron-common/README.md
Consider, for example, the following JSON message:
...
Now that we have the ability to define conditions, for each sensor we need to associate these conditions to scores. Since this is a per-sensor configuration, this fits nicely within the sensor enrichment configuration held in zookeeper. This configuration fits well within the threatIntel
section of the configuration like so:
{...,
,"threatIntel" : {
...,
, "triageConfig" : {
"riskLevelRules" : [
{
"condition1name" : level1"rule1",, "condition2comment" : level2"comment1","rule" : "<...","score" : 5,
"reason" : "some reason"},{
"name" : "rule2","comment" : "comment2",
"rule" : "<...",
"score" : 10,
"reason"aggregator" : "MAXsome reason"},...
],"aggregator" : "MAX"
}
}
}
riskLevelRules
correspond to the set of condition to numeric level mappings that define the threat triage for this particular sensor. aggregator
is an aggregation function that takes all non-zero scores representing the matching queries from riskLevelRules
and aggregates them into a single score. The current supported aggregation functions are
...
{...,"threatIntel" : {...,
, "triageConfig" : {"riskLevelRules" : { [
{"name" : "in_zeus",
"comment" : "Checks if this domain without subdomains matches against the zeus threat intel list",
"reason" : "FORMAT('%s exists in the Zeus threat intel list', domain_without_subdomains)",
"rule" : "exists(threatintels.hbaseThreatIntel.urldomain_without_subdomains.zeusList)","score" : 5},
{
"name" : "tld_check",
"comment" : "Applies a risk score based on the domain TLD",
"reason" : "FORMAT('%s does not end with com or net', domain_without_subdomains)",
"rule" : , "not(ENDS_WITH(urldomain_without_subdomains, '.com') or ENDS_WITH(urldomain_without_subdomains, '.net'))","score" : 10},"aggregator" : "MAX" }],"aggregator" : "MAX"
}
}}
In order to apply this triage configuration, we must modify the configuration for the squid
sensor in the enrichment topology. To do this, we should modify /usr/metron/0.1BETA${METRON_HOME}/config/zookeeper/sensors/squid.json
on node1.
However, since the configuration in zookeeper may have be out of sync with the configuration on disk, we must make sure they are in sync by executing the following command:
/usr/metron/0.1BETA/
$METRON_HOME/bin/zk_load_configs.sh
-m
PULL
node1:2181
-z
$ZOOKEEPER -f
/usr/metron/0.1BETA/
-o
$METRON_HOME/config/zookeeper
We should ensure that the configuration for squid exists by checking out
TODO: the directory sensors is wrong. It shoudl be changed to enrichments
cat /usr/metron/0.1BETAsensors
cat $METRON_HOME/config/zookeeper/
enrichments/squid.json
Now we can edit the configuration. In /usr/metron/0.1BETA$METRON_HOME/config/zookeeper/sensorsenrichments/squid.json
edit the section titled riskLevelRules
and add the two rules above to the map:
"exists(threatintels.hbaseThreatIntel.url.zeusList)" : 5
"not(ENDS_WITH(url, '.com') or ENDS_WITH(url, '.net'))" : 10
array. Also, ensure that the aggregator
field indicates MAX.
After modifying the configuration, we can push the configuration back to zookeeper and have the enrichment topology pick it up with live data via
/usr/metron/0.1BETA$METRON_HOME/bin/zk_load_configs.sh -m PUSH -z node1:2181$ZOOKEEPER -i /usr/metron/0.1BETA/$METRON_HOME/config/zookeeper
Now, if we reload the data from the part 4 via
tail /var/log/squid/access.log | /usr/hdp/current/kafka-broker/bin/kafka-console-producer.sh --broker-list node1:6667 $BROKERLIST --topic squid
Now, if we check the squid
index using the elasticsearch head plugin, we can see the threats triage as we would expect:
...
For URL's from cnn.com, we expect to see no threat alert, so no triage level is set. Notice . Run cnn.com with the Squid client and pipe it into Kafka
squidclient http://www.cnn.com
tail /var/log/squid/access.log -n 1 | /usr/hdp/current/kafka-broker/bin/kafka-console-producer.sh --broker-list $BROKERLIST --topic squid
Notice the lack of a threat.triage.level
field.
{
"action": "TCP_MISS",
"adapter.simplehbaseadapter.begin.ts": "1492109939268",
"adapter.simplehbaseadapter.end.ts": "1492109939280",
"adapter.threatinteladapter.begin.ts": "1492109939285",
"adapter.threatinteladapter.end.ts": "1492109939289",
"bytes": 128477,
"code": 200,
"domain_without_subdomains": "cnn.com",
"elapsed": 25,
"enrichmentjoinbolt.joiner.ts": "1492109939282",
"enrichments.hbaseEnrichment.domain_without_subdomains.whois.domain": "cnn.com",
"enrichments.hbaseEnrichment.domain_without_subdomains.whois.domain_created_timestamp": "748695600000",
"enrichments.hbaseEnrichment.domain_without_subdomains.whois.home_country": "US",
"enrichments.hbaseEnrichment.domain_without_subdomains.whois.owner": "Turner Broadcasting System, Inc.",
"enrichments.hbaseEnrichment.domain_without_subdomains.whois.registrar": "Domain Name Manager",
"enrichmentsplitterbolt.splitter.begin.ts": "1492109939265",
"enrichmentsplitterbolt.splitter.end.ts": "1492109939265",
"full_hostname": "www.cnn.com",
"guid": "bdf0d0de-3f6d-4479-848b-1c56e06050de",
"ip_dst_addr": "151.101.41.67",
"ip_src_addr": "::1",
"method": "GET",
"original_string": "1492109922.444 25 ::1 TCP_MISS/200 128477 GET http://www.cnn.com/ - DIRECT/151.101.41.67 text/html",
"source.type": "squid",
"threatinteljoinbolt.joiner.ts": "1492109939291",
"threatintelsplitterbolt.splitter.begin.ts": "1492109939283",
"threatintelsplitterbolt.splitter.end.ts": "1492109939283",
"timestamp": 1492109922444,
"url": "http://www.cnn.com/"
}
Threat Data from alamman.com has a triage level of 5
Because alammanwebtahmin.com is com is a malicious host from the zeusList
threat intel feed but is a .com
address, it's assigned threat.triage.level
of 5.
{
"action": "TCP_MISS",
"adapter.simplehbaseadapter.begin.ts": "1492109261268",
"adapter.simplehbaseadapter.end.ts": "1492109261273",
"adapter.threatinteladapter.begin.ts": "1492109261279",
"adapter.threatinteladapter.end.ts": "1492109261287",
"bytes": 69540,
"code": 200,
"domain_without_subdomains": "webtahmin.com",
"elapsed": 4288,
"enrichmentjoinbolt.joiner.ts": "1492109261274",
"enrichmentsplitterbolt.splitter.begin.ts": "1492109261266",
"enrichmentsplitterbolt.splitter.end.ts": "1492109261266",
"full_hostname": "webtahmin.com",
"guid": "cfb72fe1-376a-4850-b2b2-acd36a1f7bf7",
"ip_dst_addr": "185.59.28.14",
"ip_src_addr": "::1",
"is_alert": "true",
"method": "GET",
"original_string": "1492109249.738 4288 ::1 TCP_MISS/200 69540 GET http://webtahmin.com/ - DIRECT/185.59.28.14 text/html",
"source.type": "squid",
"threat.triage.rules.0.comment": "Checks if this domain without subdomains matches against the zeus threat intel list",
"threat.triage.rules.0.name": "in_zeus",
"threat.triage.rules.0.reason": "webtahmin.com exists in the Zeus threat intel list",
"threat.triage.rules.0.score": 5,
"threat.triage.score": 5.0,
"threatinteljoinbolt.joiner.ts": "1492109261293",
"threatintels.hbaseThreatIntel.domain_without_subdomains.zeusList": "alert",
"threatintelsplitterbolt.splitter.begin.ts": "1492109261276",
"threatintelsplitterbolt.splitter.end.ts": "1492109261276",
"timestamp": 1492109249738,
"url": "http://webtahmin.com/"
}
Threat Data from atmape.ru has a triage level of 10
Because atmape.ru is both a malicious host from the zeusList
threat intel feed as well as a non .com
and non .net
address, it's assigned threat.triage.level
of 10.
{
"action": "TCP_MEM_HIT",
"adapter.simplehbaseadapter.begin.ts": "1492108679325",
"adapter.simplehbaseadapter.end.ts": "1492108679329",
"adapter.threatinteladapter.begin.ts": "1492108679336",
"adapter.threatinteladapter.end.ts": "1492108679347",
"bytes": 3654,
"code": 200,
"domain_without_subdomains": "atmape.ru",
"elapsed": 0,
"enrichmentjoinbolt.joiner.ts": "1492108679331",
"enrichmentsplitterbolt.splitter.begin.ts": "1492108679324",
"enrichmentsplitterbolt.splitter.end.ts": "1492108679324",
"full_hostname": "www.atmape.ru",
"guid": "524aea4d-f04e-42f4-b5cf-33c8a8e1ae3b",
"ip_src_addr": "::1",
"is_alert": "true",
"method": "GET",
"original_string": "1492108654.717 0 ::1 TCP_MEM_HIT/200 3654 GET http://www.atmape.ru/ - NONE/- text/html",
"source.type": "squid",
"threat.triage.rules.0.comment": "Checks if this domain without subdomains matches against the zeus threat intel list",
"threat.triage.rules.0.name": "in_zeus",
"threat.triage.rules.0.reason": "atmape.ru exists in the Zeus threat intel list",
"threat.triage.rules.0.score": 5,
"threat.triage.rules.1.comment": "Applies a risk score based on the domain TLD",
"threat.triage.rules.1.name": "tld_check",
"threat.triage.rules.1.reason": "atmape.ru does not end with com or net",
"threat.triage.rules.1.score": 10,
"threat.triage.score": 10.0,
"threatinteljoinbolt.joiner.ts": "1492108679349",
"threatintels.hbaseThreatIntel.domain_without_subdomains.zeusList": "alert",
"threatintelsplitterbolt.splitter.begin.ts": "1492108679334",
"threatintelsplitterbolt.splitter.end.ts": "1492108679334",
"timestamp": 1492108654717,
"url": "http://www.atmape.ru/"
}
s{Wwwwww
We{hreatintels.hbaseT{hreatIntel.url.zeusList