{"description":"Trending threats, MITRE ATT\u0026CK coverage, and detection metadata — refreshed continuously.","feed_url":"https://feed.craftedsignal.io/tags/security-group/","home_page_url":"https://feed.craftedsignal.io/","items":[{"_cs_actors":[],"_cs_cves":[],"_cs_exploited":false,"_cs_products":["CloudTrail","Splunk Enterprise","Splunk Enterprise Security","Splunk Cloud","Amazon Security Lake","Splunk Add-on for Amazon Web Services"],"_cs_severities":["high"],"_cs_tags":["aws","network-acl","misconfiguration","cloud","security-group"],"_cs_type":"advisory","_cs_vendors":["Amazon","Splunk"],"content_html":"\u003cp\u003eThis detection focuses on identifying misconfigured AWS Network ACLs (NACLs) that permit unrestricted traffic. AWS NACLs act as a firewall for controlling traffic in and out of subnets within a Virtual Private Cloud (VPC). When an NACL is configured to allow all ports and protocols from any IP address (0.0.0.0/0), it effectively bypasses security controls and exposes resources to potential threats. The activity is detected by monitoring AWS CloudTrail events for \u003ccode\u003eCreateNetworkAclEntry\u003c/code\u003e or \u003ccode\u003eReplaceNetworkAclEntry\u003c/code\u003e API calls. This configuration error can be introduced by administrators during initial setup or through misconfiguration during updates. Defenders should ensure that NACLs follow the principle of least privilege to limit the attack surface.\u003c/p\u003e\n\u003ch2 id=\"attack-chain\"\u003eAttack Chain\u003c/h2\u003e\n\u003col\u003e\n\u003cli\u003eAn attacker identifies a target AWS environment.\u003c/li\u003e\n\u003cli\u003eThe attacker scans for publicly accessible services or resources.\u003c/li\u003e\n\u003cli\u003eAn administrator, either maliciously or accidentally, creates or modifies a Network ACL using the AWS Management Console, CLI, or API with overly permissive rules (allowing all traffic: \u003ccode\u003eruleAction=allow AND egress=false AND aclProtocol=-1 AND cidrBlock=0.0.0.0/0\u003c/code\u003e).\u003c/li\u003e\n\u003cli\u003eThe misconfigured NACL is applied to one or more subnets within the VPC.\u003c/li\u003e\n\u003cli\u003eThe attacker exploits the open ports and protocols to gain unauthorized access.\u003c/li\u003e\n\u003cli\u003eThe attacker attempts to move laterally within the AWS environment.\u003c/li\u003e\n\u003cli\u003eThe attacker exfiltrates sensitive data or disrupts services.\u003c/li\u003e\n\u003c/ol\u003e\n\u003ch2 id=\"impact\"\u003eImpact\u003c/h2\u003e\n\u003cp\u003eA misconfigured Network ACL that allows all traffic can have severe consequences. It can lead to unauthorized access to sensitive data, potential data breaches, service disruption, and further compromise of the AWS environment. The impact is particularly high if critical resources are located within the affected subnets. This type of misconfiguration violates security best practices and compliance requirements.\u003c/p\u003e\n\u003ch2 id=\"recommendation\"\u003eRecommendation\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003eDeploy the Sigma rule \u003ccode\u003eAWS Network ACL Created with All Ports Open\u003c/code\u003e to your SIEM to detect this specific misconfiguration (logsource: \u003ccode\u003eASL AWS CloudTrail\u003c/code\u003e, category: \u003ccode\u003enetwork_connection\u003c/code\u003e).\u003c/li\u003e\n\u003cli\u003eReview existing Network ACL configurations to identify and remediate any overly permissive rules (check AWS console or use AWS CLI/API).\u003c/li\u003e\n\u003cli\u003eImplement automated checks to validate Network ACL configurations against security best practices.\u003c/li\u003e\n\u003cli\u003eEnsure that NACLs follow the principle of least privilege by only allowing necessary traffic (review NACL \u003ccode\u003eruleAction\u003c/code\u003e, \u003ccode\u003eegress\u003c/code\u003e, \u003ccode\u003eaclProtocol\u003c/code\u003e, and \u003ccode\u003ecidrBlock\u003c/code\u003e settings in CloudTrail logs).\u003c/li\u003e\n\u003cli\u003eInvestigate any identified instances of overly permissive NACL configurations to determine the root cause and potential impact (analyze CloudTrail logs for \u003ccode\u003eCreateNetworkAclEntry\u003c/code\u003e or \u003ccode\u003eReplaceNetworkAclEntry\u003c/code\u003e events).\u003c/li\u003e\n\u003c/ul\u003e\n","date_modified":"2024-01-03T10:00:00Z","date_published":"2024-01-03T10:00:00Z","id":"/briefs/2024-01-aws-nacls-all-open/","summary":"The analytic detects the creation or replacement of AWS Network Access Control Lists (ACLs) with rules that allow all traffic from a specified CIDR block, potentially exposing the network to unauthorized access and increasing the risk of data breaches.","title":"AWS Network ACL Created with All Ports Open","url":"https://feed.craftedsignal.io/briefs/2024-01-aws-nacls-all-open/"}],"language":"en","title":"CraftedSignal Threat Feed — Security-Group","version":"https://jsonfeed.org/version/1.1"}