Name:ASL AWS Network Access Control List Deleted id:e010ddf5-e9a5-44e5-bdd6-0c919ba8fc8b version:1 date:2025-01-09 author:Patrick Bareiss, Splunk status:production type:Anomaly Description:The following analytic detects the deletion of AWS Network Access Control Lists (ACLs). It leverages AWS CloudTrail logs to identify events where a user deletes a network ACL entry. This activity is significant because deleting a network ACL can remove critical access restrictions, potentially allowing unauthorized access to cloud instances. If confirmed malicious, this action could enable attackers to bypass network security controls, leading to unauthorized access, data exfiltration, or further compromise of the cloud environment. Data_source:
-ASL AWS CloudTrail
search:`amazon_security_lake` api.operation=DeleteNetworkAclEntry status=Success | spath input=api.request.data path=egress output=egress | spath input=api.request.data path=networkAclId output=networkAclId | search egress=false | fillnull | stats count min(_time) as firstTime max(_time) as lastTime by api.operation actor.user.uid actor.user.account.uid http_request.user_agent src_endpoint.ip cloud.region networkAclId | rename actor.user.uid as user, src_endpoint.ip as src_ip, cloud.region as region, http_request.user_agent as user_agent, actor.user.account_uid as aws_account_id | `security_content_ctime(firstTime)`| `security_content_ctime(lastTime)` | `asl_aws_network_access_control_list_deleted_filter`
how_to_implement:The detection is based on Amazon Security Lake events from Amazon Web Services (AWS), which is a centralized data lake that provides security-related data from AWS services. To use this detection, you must ingest CloudTrail logs from Amazon Security Lake into Splunk. To run this search, ensure that you ingest events using the latest version of Splunk Add-on for Amazon Web Services (https://splunkbase.splunk.com/app/1876) or the Federated Analytics App. known_false_positives:It's possible that a user has legitimately deleted a network ACL. References: drilldown_searches: name:'View the detection results for - "$user$"' search:'%original_detection_search% | search user_arn = "$user$"' 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 Network ACL Activity' asset_type:AWS Instance confidence:50 impact:10 message:User $user$ from $src_ip$ has sucessfully deleted network ACLs entry. mitre_attack_id: - 'T1562.007' - 'T1562' observable: name:'src_ip' type:'IP Address' - role: - 'Attacker' name:'user' type:'User' - role: - 'Victim' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' required_fields: - 'api.operation' - 'api.request.data' - 'actor.user.uid' - 'actor.user.account.uid' - 'http_request.user_agent' - 'src_endpoint.ip' - 'cloud.region' risk_score:5 security_domain:network
