[Rule tuning] existing strace activity rule. (#2028)

* Update description and MITTRE Attack details

(cherry picked from commit 2ee23bd80f)

rules/linux/privilege_escalation_linux_strace_activity.toml

@@ -1,13 +1,14 @@
 [metadata]
 creation_date = "2020/02/18"
 maturity = "production"
-updated_date = "2021/03/03"
+updated_date = "2021/06/15"
 
 [rule]
 author = ["Elastic"]
 description = """
-Strace runs in a privileged context and can be used to escape restrictive environments by instantiating a shell in order
-to elevate privileges or move laterally.
+Strace is a useful diagnostic, instructional, and debugging tool. This rule identifies a privileged context execution of
+strace which can be used to escape restrictive environments by instantiating a shell in order to elevate privileges or
+move laterally.
 """
 false_positives = [
     """
@@ -24,7 +25,7 @@ references = ["https://en.wikipedia.org/wiki/Strace"]
 risk_score = 21
 rule_id = "d6450d4e-81c6-46a3-bd94-079886318ed5"
 severity = "low"
-tags = ["Elastic", "Host", "Linux", "Threat Detection"]
+tags = ["Elastic", "Host", "Linux", "Threat Detection", "Privilege Escalation"]
 timestamp_override = "event.ingested"
 type = "query"
 
@@ -32,3 +33,17 @@ query = '''
 event.category:process and event.type:(start or process_started) and process.name:strace
 '''
 
+
+[[rule.threat]]
+framework = "MITRE ATT&CK"
+[[rule.threat.technique]]
+id = "T1068"
+name = "Exploitation for Privilege Escalation"
+reference = "https://attack.mitre.org/techniques/T1068/"
+
+
+[rule.threat.tactic]
+id = "TA0004"
+name = "Privilege Escalation"
+reference = "https://attack.mitre.org/tactics/TA0004/"
+