AWS CloudTrail Log Monitoring & Threat Detection
Monitoring AWS Identity and Access Management (IAM) activity is critical for detecting unauthorized access and IAM abuse. This guide focuses on securing AWS by analyzing CloudTrail JSON event logs to identify privilege escalation attempts, unauthorized data exfiltration from S3, and automated API abuse.
Understanding the CloudTrail JSON Structure
Unlike traditional web server logs, AWS CloudTrail delivers highly structured JSON records representing individual API calls across your infrastructure.
{
"eventVersion": "1.08",
"userIdentity": {
"type": "IAMUser",
"userName": "developer-temp"
},
"eventTime": "2026-03-30T10:00:00Z",
"eventSource": "s3.amazonaws.com",
"eventName": "GetObject",
"sourceIPAddress": "203.0.113.50",
"errorCode": "AccessDenied"
}CloudTrail vs VPC Flow Logs
CloudTrail answers "Who made this API call, when, and from where?" (e.g., Who deleted that database?). VPC Flow Logs capture raw IP network traffic traversing your network interfaces, which is crucial for identifying port scanning or network-layer DDoS, but lacks IAM context.
CloudTrail vs CloudWatch Logs
CloudTrail specifically records AWS API activity and account management events (e.g., creating an EC2 instance). CloudWatch Logs captures the actual application and operating system logs generated *inside* those resources (e.g., the Nginx access logs from inside that EC2 instance). You need both for comprehensive security.
Common Attack Signatures in AWS
Cloud attackers often execute automated scripts to discover what permissions they have. Look for rapid spikes in Access Denied errors indicating an attacker probing your IAM boundaries, or unusual spikes in read activity pointing to data exfiltration.
AWS Access Denied
Identify IAM abuse and credential harvesting by analyzing Client.UnauthorizedOperation errors.
Data Exfiltration
Detect compromised credentials dumping sensitive S3 buckets or RDS snapshots to external IPs.
Explore the full threat detection library for more attack patterns.
Compare Log Analysis Across Platforms
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