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Event Information

  • The DeleteDhcpOptions event in AWS for EC2 refers to the deletion of a DHCP options set associated with a Virtual Private Cloud (VPC).
  • DHCP options sets in AWS EC2 are used to configure network settings for instances within a VPC, such as DNS servers, domain names, and NTP servers.
  • When the DeleteDhcpOptions event occurs, it means that the specified DHCP options set has been successfully deleted, and any instances associated with that DHCP options set will no longer receive the configured network settings.

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Examples

  • Unauthorized deletion of DHCP options: If security is impacted with DeleteDhcpOptions in AWS for EC2, it could potentially allow unauthorized individuals to delete DHCP options. This could lead to disruption of network connectivity and potential security breaches.

  • Misconfiguration of DHCP options: Deleting DHCP options without proper planning and configuration can result in misconfigured network settings. This can lead to network connectivity issues, misrouted traffic, and potential security vulnerabilities.

  • Loss of network functionality: Deleting DHCP options without proper backup or understanding of the impact can result in loss of network functionality. This can disrupt communication between EC2 instances, affect application availability, and impact overall system performance.

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Remediation

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Using Console

  1. Example 1: Unauthorized Access to AWS EC2 Instance

    • Step 1: Identify the compromised EC2 instance by reviewing the event logs or security alerts.
    • Step 2: Terminate the compromised EC2 instance to prevent further unauthorized access.
    • Step 3: Launch a new EC2 instance with the latest AMI and apply necessary security configurations, such as disabling unnecessary ports, implementing strong access controls, and enabling encryption.

  2. Example 2: Unusual Network Traffic from AWS EC2 Instance

    • Step 1: Analyze the network traffic logs or security alerts to identify the source and destination of the unusual traffic.
    • Step 2: Disable or block the suspicious network traffic by modifying the security group rules associated with the affected EC2 instance.
    • Step 3: Implement additional security measures, such as enabling VPC flow logs, configuring network ACLs, or using a web application firewall (WAF) to protect against future network-based attacks.

  3. Example 3: High CPU Utilization on AWS EC2 Instance

    • Step 1: Monitor the CPU utilization metrics of the EC2 instance using CloudWatch or any other monitoring tool.
    • Step 2: Identify the process or application causing the high CPU utilization by analyzing the performance metrics or using profiling tools.
    • Step 3: Optimize the application or adjust the EC2 instance’s resources (e.g., increase CPU, memory) to handle the workload efficiently. Consider implementing auto-scaling to automatically adjust resources based on demand.

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Using CLI

  1. Ensure that all EC2 instances are using the latest Amazon Machine Images (AMIs) by regularly checking for updates and patching any vulnerabilities. Use the following AWS CLI commands:

    • List all EC2 instances: aws ec2 describe-instances
    • Identify instances with outdated AMIs: aws ec2 describe-images --owners amazon --filters "Name=name,Values=amzn-ami-hvm-*" --query 'Images[*].[ImageId,CreationDate]' --output text | sort -k2 | tail -n 1
    • Update the AMI for the identified instances: aws ec2 create-image --instance-id <instance-id> --name "Updated AMI" --description "Updated AMI for security patching"
    • Terminate the old instance and launch a new instance using the updated AMI.

  2. Implement security groups and network ACLs to restrict inbound and outbound traffic to only necessary ports and protocols. Use the following AWS CLI commands:

    • List all security groups: aws ec2 describe-security-groups
    • Identify security groups with overly permissive rules: aws ec2 describe-security-groups --filters Name=ip-permission.cidr,Values=0.0.0.0/0
    • Update the security group rules to allow only required traffic: aws ec2 revoke-security-group-ingress --group-id <security-group-id> --protocol <protocol> --port <port> --cidr <cidr>
    • Repeat the above command for each unnecessary rule.

  3. Enable AWS CloudTrail to monitor and log all API activity within your AWS account. Use the following AWS CLI commands:

    • Create a new S3 bucket to store CloudTrail logs: aws s3api create-bucket --bucket <bucket-name> --region <region>
    • Enable CloudTrail for your AWS account: aws cloudtrail create-trail --name <trail-name> --s3-bucket-name <bucket-name>
    • Start logging API activity: aws cloudtrail start-logging --name <trail-name>
    • Verify that CloudTrail is enabled: aws cloudtrail describe-trails --trail-name-list <trail-name>

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Using Python

  1. Example 1: Enforce secure communication for AWS EC2 instances using SSL/TLS

    • Generate an SSL/TLS certificate for the EC2 instance using a trusted certificate authority (CA).
    • Install the certificate on the EC2 instance and configure the web server to use HTTPS.
    • Update the security group rules to allow inbound traffic on port 443 (HTTPS) and deny traffic on port 80 (HTTP).

    Python script:

    # Install required packages
import subprocess
subprocess.call(['pip', 'install', 'boto3'])

import boto3

# Generate SSL/TLS certificate using ACM
acm_client = boto3.client('acm', region_name='us-west-2')
response = acm_client.request_certificate(
    DomainName='example.com',
    ValidationMethod='DNS'
)
certificate_arn = response['CertificateArn']

# Install certificate on EC2 instance
ec2_client = boto3.client('ec2', region_name='us-west-2')
response = ec2_client.associate_iam_instance_profile(
    IamInstanceProfile={
        'Arn': 'arn:aws:iam::123456789012:instance-profile/EC2-SSL-Profile'
    },
    InstanceId='i-1234567890abcdef0'
)

# Configure web server to use HTTPS
# (Specific steps depend on the web server software being used)

# Update security group rules
response = ec2_client.authorize_security_group_ingress(
    GroupId='sg-0123456789abcdef0',
    IpPermissions=[
        {
            'FromPort': 443,
            'ToPort': 443,
            'IpProtocol': 'tcp',
            'IpRanges': [{'CidrIp': '0.0.0.0/0'}]
        },
        {
            'FromPort': 80,
            'ToPort': 80,
            'IpProtocol': 'tcp',
            'IpRanges': [{'CidrIp': '0.0.0.0/0'}],
            'UserIdGroupPairs': [{'GroupId': 'sg-0123456789abcdef0'}]
        }
    ]
)

  2. Example 2: Enable encryption at rest for AWS EC2 EBS volumes

    • Create a new AWS Key Management Service (KMS) customer master key (CMK) or use an existing one.
    • Enable encryption for the EBS volumes by specifying the CMK during volume creation or by modifying the existing volumes.
    • Update the EC2 instance configuration to ensure that the encrypted EBS volumes are mounted and used.

    Python script:

    # Install required packages
import subprocess
subprocess.call(['pip', 'install', 'boto3'])

import boto3

# Create a new KMS CMK or use an existing one
kms_client = boto3.client('kms', region_name='us-west-2')
response = kms_client.create_key(
    Description='EC2 EBS Encryption Key',
    KeyUsage='ENCRYPT_DECRYPT',
    Origin='AWS_KMS',
    BypassPolicyLockoutSafetyCheck=False
)
cmk_arn = response['KeyMetadata']['Arn']

# Enable encryption for EBS volumes
ec2_client = boto3.client('ec2', region_name='us-west-2')
response = ec2_client.modify_instance_attribute(
    InstanceId='i-1234567890abcdef0',
    BlockDeviceMappings=[
        {
            'DeviceName': '/dev/sda1',
            'Ebs': {
                'Encrypted': True,
                'KmsKeyId': cmk_arn
            }
        }
    ]
)

# Update EC2 instance configuration to mount and use encrypted EBS volumes
# (Specific steps depend on the operating system and configuration management tool being used)

  3. Example 3: Implement AWS EC2 instance backups using AWS Backup

    • Create an AWS Backup plan specifying the backup schedule, retention period, and backup vault.
    • Assign the backup plan to the EC2 instances that need to be backed up.
    • Monitor the backup status and perform restores as needed.

    Python script:

    # Install required packages
import subprocess
subprocess.call(['pip', 'install', 'boto3'])

import boto3

# Create an AWS Backup plan
backup_client = boto3.client('backup', region_name='us-west-2')
response = backup_client.create_backup_plan(
    BackupPlan={
        'BackupPlanName': 'EC2-Backup-Plan',
        'Rules': [
            {
                'RuleName': 'DailyBackup',
                'ScheduleExpression': 'cron(0 0 * * ? *)',
                'TargetBackupVaultName': 'EC2-Backup-Vault',
                'Lifecycle': {
                    'DeleteAfterDays': 30
                }
            }
        ]
    }
)
backup_plan_id = response['BackupPlanId']

# Assign the backup plan to EC2 instances
response = backup_client.create_backup_selection(
    BackupPlanId=backup_plan_id,
    BackupSelection={
        'SelectionName': 'EC2-Backup-Selection',
        'IamRoleArn': 'arn:aws:iam::123456789012:role/EC2-Backup-Role',
        'Resources': [
            'arn:aws:ec2:us-west-2:123456789012:instance/i-1234567890abcdef0'
        ]
    }
)

# Monitor backup status and perform restores as needed
# (Specific steps depend on the backup management tool being used)