Name:AWS Excessive Security Scanning id:1fdd164a-def8-4762-83a9-9ffe24e74d5a version:3 date:2024-09-30 author:Patrick Bareiss, Splunk status:production type:TTP Description:The following analytic identifies excessive security scanning activities in AWS by detecting a high number of Describe, List, or Get API calls from a single user. It leverages AWS CloudTrail logs to count distinct event names and flags users with more than 50 such events. This behavior is significant as it may indicate reconnaissance activities by an attacker attempting to map out your AWS environment. If confirmed malicious, this could lead to unauthorized access, data exfiltration, or further exploitation of your cloud infrastructure. Data_source:
-AWS CloudTrail
search:`cloudtrail` eventName=Describe* OR eventName=List* OR eventName=Get* | stats dc(eventName) as dc_events min(_time) as firstTime max(_time) as lastTime values(eventName) as command values(src) as src values(userAgent) as userAgent by user userIdentity.arn | where dc_events > 50 | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`|`aws_excessive_security_scanning_filter`
how_to_implement:You must install splunk AWS add on and Splunk App for AWS. This search works with AWS CloudTrail logs. known_false_positives:While this search has no known false positives. References: -https://github.com/aquasecurity/cloudsploit drilldown_searches: name:'View the detection results for - "$user$"' search:'%original_detection_search% | search user = "$user$"' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' name:'View risk events for the last 7 days for - "$user$"' search:'| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$user$") starthoursago=168 | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' tags: analytic_story: - 'AWS User Monitoring' asset_type:AWS Account confidence:60 impact:30 message:User $user$ has excessive number of api calls $dc_events$ from these IP addresses $src$, violating the threshold of 50, using the following commands $command$. mitre_attack_id: - 'T1526' observable: name:'src' type:'IP Address' - role: - 'Attacker' name:'user' type:'User' - role: - 'Victim' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' required_fields: - '_time' - 'eventName' - 'src' - 'userAgent' - 'user' - 'userIdentity.arn' risk_score:18 security_domain:network
