AWS Management Console Brute Force of Root User Identity

This alert identifies potential brute-force attempts targeting the AWS root user account. The AWS root user has unrestricted privileges, making it a high-value target for attackers. This activity is characterized by a high number of failed ConsoleLogin events (event.outcome: failure with userIdentity.type: Root) within a short timeframe from the same IP address or user agent. Even if no login succeeds, this activity may indicate reconnaissance, password spraying, or credential stuffing attempts targeting the root user. The alert leverages a threshold rule that triggers when the number of failed login attempts exceeds a predefined threshold. Defenders should investigate the source IP addresses, user agents, and timestamps to identify and mitigate the attack.

Attack Chain

1. Initial Access: The attacker attempts to gain initial access by targeting the AWS Management Console login page.
2. Credential Guessing: The attacker initiates a brute-force attack, attempting multiple password combinations for the root user.
3. Authentication Failure: Each incorrect password attempt results in a ConsoleLogin event with event.outcome: failure and userIdentity.type: Root in AWS CloudTrail logs.
4. Threshold Trigger: The number of failed login attempts from the same IP or user agent exceeds a pre-defined threshold, triggering the detection rule.
5. Privilege Escalation (Conditional): If the attacker successfully guesses the password, they gain complete access to the AWS account with root privileges.
6. Resource Access: The attacker leverages root privileges to access and control all AWS resources, including EC2 instances, S3 buckets, and databases.
7. Data Exfiltration/Destruction (Conditional): With complete access, the attacker can exfiltrate sensitive data or destroy critical infrastructure.
8. Persistence (Conditional): The attacker may create new IAM users or modify existing roles to maintain persistent access to the AWS environment.

Impact

A successful brute-force attack on the AWS root user can lead to complete compromise of the AWS account. This can result in unauthorized access to sensitive data, data exfiltration, service disruption, and financial loss. The impact can be severe, potentially affecting all services and resources within the AWS account. The AWS Incident Response Playbooks classify root login attempts as Priority-1 credential compromise events.

Recommendation

• Deploy the Sigma rule AWS Management Console Root User Brute Force Detection to your SIEM to detect brute-force attempts based on failed login events (logsource: aws/cloudtrail, category: authentication).
• Enable Multi-Factor Authentication (MFA) on the root account and enforce it for all users to prevent unauthorized access, mitigating T1110 (Credential Access).
• Rotate the root password immediately using AWS’s password reset function to prevent further brute-force attempts, referencing the AWS documentation on root user tasks.
• Block offending IPs or networks using AWS WAF, VPC network ACLs, or Security Groups to prevent further malicious attempts (logsource: aws/firewall, category: network_connection).