A security engineer receives a notice from the AWS Abuse team about suspicious activity from a Linux-based Amazon EC2 instance that uses Amazon Elastic Block Store (Amazon EBS-based storage The instance is making connections to known malicious addresses. The instance is in a development account within a VPC that is in the us-east-1 Region The VPC contains an internet gateway and has a subnet in us-east-1a and us-easMb Each subnet is associate with a route table that uses the internet gateway as a default route Each subnet also uses the default network ACL The suspicious EC2 instance runs within the us-east-1 b subnet. During an initial investigation a security engineer discovers that the suspicious instance is the only instance that runs in the subnet
Which response will immediately mitigate the attack and help investigate the root cause?

Question

A security engineer receives a notice from the AWS Abuse team about suspicious activity from a Linux-based Amazon EC2 instance that uses Amazon Elastic Block Store (Amazon EBS>-based storage The instance is making connections to known malicious addresses. The instance is in a development account within a VPC that is in the us-east-1 Region The VPC contains an internet gateway and has a subnet in us-east-1a and us-easMb Each subnet is associate with a route table that uses the internet gateway as a default route Each subnet also uses the default network ACL The suspicious EC2 instance runs within the us-east-1 b subnet. During an initial investigation a security engineer discovers that the suspicious instance is the only instance that runs in the subnet

Which response will immediately mitigate the attack and help investigate the root cause?

Nguyen Tan Hung · Accepted Answer

Update the outbound network ACL for the subnet in us-east-1b to explicitly deny all connections as the first rule Replace the security group with a new security group that allows connections only from a diagnostics security group Update the outbound network ACL for the us-east-1b subnet to remove the deny all rule Launch a new EC2 instance that has diagnostic tools Assign the new security group to the new EC2 instance Use the new EC2 instance to investigate the suspicious instance

Nguyen Tan Hung · Answer

Log in to the suspicious instance and use the netstat command to identify remote connections Use the IP addresses from these remote connections to create deny rules in the security group of the instance Install diagnostic tools on the instance for investigation Update the outbound network ACL for the subnet in us-east- lb to explicitly deny all connections as the first rule during the investigation of the instance

Nguyen Tan Hung · Answer

Ensure that the Amazon Elastic Block Store (Amazon EBS) volumes that are attached to the suspicious EC2 instance will not delete upon termination Terminate the instance Launch a new EC2 instance in us-east-1a that has diagnostic tools Mount the EBS volumes from the terminated instance for investigation

Nguyen Tan Hung · Answer

Create an AWS WAF web ACL that denies traffic to and from the suspicious instance Attach the AWS WAF web ACL to the instance to mitigate the attack Log in to the instance and install diagnostic tools to investigate the instance

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