Elastic Compute Service:ECS instance security

Cloud computing security, or cloud security, usually refers to the practice of using a set of policies, controls, and technologies to protect data, infrastructure, and applications within a cloud computing environment from both external and internal cybersecurity threats and vulnerabilities. An ever-growing number of enterprises attach greater importance to cloud security compliance. Security compliance in the cloud depends on a top-down top-level design. To ensure security compliance in the cloud, you must develop cloud-based applications with security in mind.

Enable MFA for accounts

We recommend that you enable MFA for your Alibaba Cloud account. MFA enhances security because it requires you to provide MFA security codes in addition to usernames and passwords when you access Alibaba Cloud services. MFA security codes are dynamically generated by MFA devices.

Use RAM users instead of Alibaba Cloud accounts and attach appropriate permissions policies to the users

Use instance RAM roles instead of AccessKey pairs to call API operations

Typically, applications that are deployed on ECS instances access the APIs of other Alibaba Cloud services by using the AccessKey pair of an Alibaba Cloud account or RAM user. Before the AccessKey pair can be used on an instance to call API operations, the AccessKey pair must be configured in the instance. For example, you can write the AccessKey pair to a configuration file of the instance. However, this method carries security risks such as information leaks and difficult maintenance. To address these risks, Alibaba Cloud provides instance RAM roles. By using instance RAM role, you can ensure the security of your AccessKey pairs and make use of RAM for fine-grained control and management of permissions.

You can attach an instance RAM role to an ECS instance and use a Security Token Service (STS) temporary credential to access the APIs of other Alibaba Cloud services. After you attach the role to the instance, we recommend that you access instance metadata in security hardening mode. The STS temporary credential is updated periodically. For more information, see Overview.

Prevent AccessKey pair leaks

AccessKey pairs are credentials for Alibaba Cloud accounts to access APIs and must be kept secure. Do not expose your AccessKey pairs to external channels such as GitHub to prevent security threats caused by malicious uses. If the AccessKey pair of your Alibaba Cloud account is disclosed, your resources are exposed to risks.

Security suggestions for managing accounts and passwords

Automatically manage and audit cloud resources in bulk to prevent individual assets being left unprotected due to incorrect configurations. We recommend that you use uniform deployment and naming conventions for instances and security groups and periodically check for, be warned of, and delete security groups or instances that do not comply with the naming conventions. Use tags to manage resources in bulk, use Cloud Assistant to automate O&M on resource channels, use Cloud Config to conduct compliance audits on resources, and use Application Configuration Management (ACM) to centralize the management of all application configurations.

Use tags to manage resources in bulk

• Use tags to identify, categorize, and find cloud resources in bulk. In the event of a security incident, you can use tags to quickly identify the scope and impact severity of the incident.

• You can configure security policies with specific tags for resources, such as security groups, at a time.

For more information, see Tags.

Use Cloud Assistant to automate O&M on resource channels

Use Cloud Config to conduct compliance audits on resources

Cloud Config is a service that allows you to evaluate cloud resources. Cloud Config aggregates resources in different regions to accelerate the query of resources. Cloud Config takes snapshots to record configuration changes of each monitored resource and displays the configuration changes over time in a configuration timeline. Resource configuration changes can trigger compliance evaluation. Cloud Config generates alerts for non-compliant configurations. Cloud Config allows you to monitor the compliance of large amounts of cloud resources against internal and external compliance requirements. For more information, see What is Cloud Config?

Use ACM to centralize the management of application configurations

ACM is a utility service that centrally manages and pushes application configurations in a distributed architecture environment. ACM offers a host of features such as configuration modification, configuration push, historical version management, canary release, and configuration modification audit. With these features, ACM helps you centralize the management of configurations in every application, reduce configuration management costs in distributed systems, and lower the risks of decreased availability or even failures caused by incorrect configuration changes. For more information, see What is ACM?

Host business that requires high security on security-enhanced instances

Use secure images

• Use public images and enable security hardening for the images.

  • Use public images provided by Alibaba Cloud.

  • Enable security hardening that is free of charge for public images to obtain various security features, such as webshell detection, security configuration check, and alerting for unusual logons to servers.

  

• Use encrypted custom images.

  Use the AES-256 algorithm to encrypt custom images to prevent data leaks in case of image disclosure. You can create encrypted system and encrypted data disks and then create encrypted custom images based on these disks. You can also use the Copy and Encrypt feature when you copy an unencrypted custom image to encrypt the image copy. If you want to share encrypted custom images, we recommend that you create separate BYOK keys (custom keys imported by using Bring Your Own Key feature) for the images to prevent key leaks. For more information, see Copy a custom image.

Encrypt data on disks by using KMS

Use snapshots for disaster recovery purposes

• Use snapshots to back up data

  Data backup is the foundation of disaster recovery and helps reduce the risk of data loss caused by system failures, accidental operations, and security issues. ECS provides the snapshot feature to meet the data backup requirements of most users. You can select a method of creating snapshots based on your needs. For more information, see Create a snapshot for a disk.

  We recommend that you create automatic snapshots on a daily basis and retain the snapshots for at least seven days. This significantly improves disaster tolerance and minimizes potential data loss.

  

• Use encrypted snapshots

  ECS uses the industry-standard AES-256 algorithm and keys to encrypt snapshots and prevent data leaks in case of snapshot disclosure. You can create encrypted disks and then create encrypted snapshots from the disks.

Access instance metadata in security hardening mode

ECS instance metadata includes the information of ECS instances in Alibaba Cloud. You can view the metadata of running instances and configure or manage the instances based on their metadata. For more information, see Overview of ECS instance metadata.

Cloud computing leverages Virtual Private Cloud (VPC) to abstract physical networks into isolated secure virtual networks and pool network resources to provide isolation at the data link layer. VPCs are completely isolated from each other and can be connected only by using elastic IP addresses or NAT IP addresses. You can configure IP address ranges or CIDR blocks, route tables, gateways within each VPC. You can connect on-premises data centers to VPCs or connect networks around the world to build a customized network environment so that you can smoothly migrate applications to the cloud or scale the data centers. To connect on-premises data centers to VPCs, you can use VPN Gateway, Express Connect, or Smart Access Gateway (SAG). To connect networks worldwide, you can use Cloud Enterprise Network (CEN).

Networks are the basis of cloud services. Networks are vulnerable to various severe cyberattacks and difficult to protect. Cloud computing platforms provide a mature cybersecurity architecture to defend against threats from the Internet. In Alibaba Cloud, you can use security groups, network access control lists (ACLs), routing policies, or Express Connect circuits to control access to VPCs. In addition, you must configure security protections such as Cloud Firewall, WAF, and Anti-DDoS to protect against external cyberthreats.

Follow the security suggestions for isolating network resources

Build a secure network environment

• Properly configure security groups to isolate networks and reduce attack surface

  Security groups are an important component of network security isolation and are used to control network access to or from ECS instances. The rules of a security group control inbound traffic to and outbound traffic from the instances that are associated with the security group. You can configure security group rules to filter traffic based on port numbers and IP addresses so that you can reduce the attack surface and protect your instances.

  For example, port 22 is used as the remote connection port on Linux instances by default. Security risks arise if this port is open to external access. You can configure security group rules to allow only specific local IP addresses access to the instances over port 22. If you have higher security requirements, you can use third-party virtual private network (VPN) products to encrypt logon data. Consider the security suggestions described in the following table.

  Suggestion	Description	References
  Principle of least privilege	Security groups are expected to work like whitelists. Therefore, open and expose as few ports as you need and allocate as few public IP addresses as you need. To query task logs or perform troubleshooting on an instance, log on to the instance by using a VPN or bastion host. Incorrect configurations may leave service ports or IP addresses exposed to the Internet and result in cybersecurity threats. You can create security groups to prevent unauthorized access. You need to open only the ports required by business in security groups that govern Internet traffic and those that govern internal network traffic. For high-risk service ports on ECS instances, you must allow access only from your computer or configure security group rules to allow access only from specific IP addresses. For the management backend of HTTP services, you must configure security group rules to allow access only from specific IP addresses. Enable WAF features for the domain name of the HTTP service.	Security groups for different use cases
  Do not set 0.0.0.0/0 as an authorization object in your security group rules.	Allowing all inbound access is a common mistake. 0.0.0.0/0 indicates all IP addresses. If a security group rule includes 0.0.0.0/0 as an authorization object to allow inbound access, the rule opens all ports to external access. This poses high security risks. To improve security posture, we recommend that you deny external access over all ports and then configure security group rules to open ports based on your needs. For example, if you need to expose web services, you can open common TCP ports such as ports 80, 8080, and 443 and keep other ports closed.	Add a security group rule
  Disable inbound security group rules that are no longer needed.	If an inbound security group rule includes 0.0.0.0/0, review the ports and services that your applications must expose. If you do not want specific ports to directly provide external services, you can add a Deny (Forbid) rule for the ports. For example, if you deploy MySQL database services on your instance, port 3306 cannot be exposed to the Internet. In this case, you can add a Deny rule and set the priority of the rule to 100, which indicates the lowest priority.	Add a security group rule
  Reference security groups as authorization objects in security group rules.	Rules must be added to security groups to allow access based on the principle of lease privilege. Different application layers must use different security groups with appropriate inbound and outbound rules. For example, you can create different security groups for distributed applications. These security groups may not be accessible to each other. In this case, you can add security group rules that reference security groups (instead of IP addresses or CIDR blocks) as authorization objects to allow mutual access between the security groups so that resources in these security groups can access each other. For example, assume that you create the sg-web security group for the web layer and the sg-database security group for the database layer of your applications. In sg-database, you can add a rule that references the sg-web security group to allow all resources in the sg-web security group access over port 3306.	Add a security group rule
  For security groups of the classic network type, do not set CIDR blocks or IP addresses as authorization objects in rules that govern internal network traffic.	By default, no inbound rules for internal network traffic are enabled for ECS instances that reside in the classic network. Exercise caution when you configure security group rules that govern internal network traffic.	Security group rule
  Configure appropriate names and tags for security groups.	Appropriate names and descriptions help you identify security groups. You can modify the names and descriptions of security groups. You can add tags to security groups by using the ECS console or by calling API operations for easy search and management.	Modify a security group Create or add a tag
  Add ECS instances that require mutual access to the same security group.	Each ECS instance can belong to up to five security groups. ECS instances within the same security group can communicate with each other over the internal network. If you have multiple security groups but do not want to configure multiple security group rules, you can create another security group and add the instances that require internal network communication to the new security group. We recommend that you do not add all of your ECS instances to the same security group. For a large or medium-sized application that is distributed across multiple ECS instances, each of these instances plays a different role. You cannot add all the instances to the same security group and must properly configure inbound and outbound security group rules for each instance.	Manage ECS instances in security groups
  Isolate instances within a security group.	Security groups act as virtual firewalls that provide Stateful Packet Inspection (SPI), also known as dynamic packet filtering. A security group contains instances that reside in the same region. These instances have the same security requirements and trust each other. Alibaba Cloud fine-tunes the internal access control policies (or internal network communication policies) of security groups to isolate instances within a security group.	Network isolation within a basic security group
  Use security group quintuple rules.	Security groups are used to control network access to or from one or more ECS instances. Security groups are an important component of security isolation and are used to logically isolate security domains in the cloud. Security group quintuple rules allow you to implement precise access control based on the following five elements: source IP address, source port, destination IP address, destination port, and transport layer protocol.	Security group quintuple rules
  Add ECS instances that provide Internet-facing services and those that provide internal network-facing services to different security groups.	Applications hosted on an ECS instance may be accessible to the Internet in scenarios in which the instance provides Internet-facing services. These scenarios include those in which the instance proactively exposes specific ports (such as ports 80 and 443) for external access and in which the instance passively provides port forwarding rules (such as NAT port forwarding rules and forwarding rules that are based on the system-assigned public IP address or elastic IP address of the instance). In the preceding scenarios, use the strictest security group rules for the instance. Add a rule to deny access over all protocols and all ports and then add rules to allow access only to ports required by external services, such as ports 80 and 443. If a security group contains only Internet-facing ECS instances, the rules in the security group are easy to adjust. Internet-facing ECS instances within the same security group must have clear and simple responsibilities to ensure that the instances provide no services other than their primary services. For example, for MySQL and Redis applications, we recommend that you deploy them on ECS instances that do not provide Internet access, and then configure security group rules to allow access from specific security groups to the instances.	Add a security group rule

• Configure security domains to isolate services of different security levels within your organization

  You can build private networks by using VPCs to separately host servers of different security levels in your organization and ensure that the servers do not interfere with each other over an interconnected network. We recommend that you create a VPC, assign a private IP address range in CIDR notation to the VPC, and configure route tables and gateways for the VPC. Then, you can store important data in this VPC, which is logically isolated from the Internet, and use an elastic IP address (EIP) or a jump server to manage data for daily O&M purposes. For more information, see Create and manage a VPC.

• Use jump servers or bastion hosts to protect against internal and external intrusions

  Jump servers have a large set of permissions. If you use a jump server, you must use tools to thoroughly record and audit operations on it. We recommend that you use bastion hosts instead to prevent your networks and data from being hacked or disrupted by attackers. Use various technical methods to monitor and record the operations that your O&M personnel perform on servers, network devices, security devices, and databases in your networks, so that your troubleshooting or O&M personnel can be alerted in a centralized manner, handle the alerts in a timely manner, audit the operations, and determine who is responsible for accidental operations or faults.

  We recommend that you assign the jump server to a dedicated vSwitch in a VPC and then associate the corresponding EIP or NAT port forwarding table with the jump server. Create a dedicated security group named SG_BRIDGE and open required ports. For example, open TCP port 22 for Linux operating systems and RDP port 3389 for Windows operating systems. To restrict inbound access, you can add security group rules to allow only specific public IP addresses of your organization to access the security group. This way, the probability that resources are scanned or accessed is reduced. Add the ECS instance that functions as a jump server to the security group. If you want the jump server to access ECS instances within another security group, you can configure a rule that allows the jump server access to that security group. For example, in a security group named SG_CURRENT, you can add a rule to allow access from the SG_BRIDGE security group over specific protocols and ports. When you use the jump server for SSH communication, we recommend that you use key pairs instead of passwords to log on to ECS instances. For information about key pairs, see SSH key pair overview.

• Properly assign public IP addresses to reduce Internet-exposed attack surface

  Proper allocation of public IP addresses facilitates Internet access management and reduces attack surface regardless of whether ECS instances reside in the classic network or VPCs. For ECS instances that reside in a VPC, we recommend that you connect the instances that require Internet access to several specified vSwitches. This makes the instances easy to audit and distinguish and helps prevent accidental exposure of ECS instances to the Internet.

  • Most distributed applications have different layers and groups. For ECS instances that do not provide Internet access, we recommend that you do not assign public IP addresses. For multiple instances that provide Internet access, we recommend that you configure Server Load Balancer (SLB) instances to distribute Internet traffic to improve system availability. For more information, see SLB overview.

  • If your ECS instances require Internet access but do not have public IP addresses, we recommend that you use NAT gateways to provide Internet proxy services for the instances. You need only to configure SNAT entries to provide Internet access for specific CIDR blocks or subnets. This way, you can prevent services from being exposed to the Internet after public IP addresses are assigned, when only outbound Internet access is required. For more information, see What is VPN Gateway?

Use Anti-DDoS Origin Basic (free-of-charge), Anti-DDoS Pro, and Anti-DDoS Premium to mitigate DDoS attacks

In a DDoS attack, multiple compromised computer systems flood one or more targets with fraudulent traffic to deny service to legitimate users of the targets. Alibaba Cloud Security Center can defend against Layer 3 to Layer 7 DDoS attacks, including SYN flood, UDP flood, ACK flood, ICMP flood, DNS flood, and HTTP flood attacks. Anti-DDoS Origin Basic provides a DDoS mitigation capacity of up to 5 Gbit/s free of charge.

By default, Anti-DDoS Origin Basic is enabled on ECS instances. Anti-DDoS Origin Basic allows you to maintain normal access speeds in case of DDoS attacks without the need to purchase expensive traffic scrubbing devices. Anti-DDoS Origin Basic ensures the expected bandwidth, availability, and stability of your business. In this case, your business is not affected by other users. After an ECS instance is created, you can set scrubbing thresholds for it. For more information, see Configure a traffic scrubbing threshold.

Use Security Center Basic for free to protect against exploitation of system vulnerabilities

Security Center is a centralized security management system that identifies, analyzes, and warns of security threats in real time. Security Center provides multiple features to ensure the security of cloud resources and servers in data centers. The features include anti-ransomware, antivirus, web tamper proofing, and compliance check. You can use Security Center to automate security operations, responses, and threat tracing, and meet regulatory compliance requirements.

Security Center Basic is available to you by default. Security Center Basic scans only for the following threats: unusual logons to servers, vulnerabilities, and configuration risks in cloud services. To use advanced features such as threat detection, vulnerability fixing, and virus detection and removal, go to the Security Center console to purchase a paid Security Center edition. For more information, see Introduction to Security Center Basic.

Use WAF to protect against exploitation of system vulnerabilities

Web Application Firewall (WAF) depends on the big data capabilities of Alibaba Cloud Security Center to protect web applications against common attacks reported by the Open Web Application Security Project (OWASP) and HTTP flood attacks. The attacks include SQL injections, cross-site scripting (XSS) attacks, webshells, trojans, and unauthorized access. WAF blocks malicious visits to prevent data leaks and ensure the security and availability of your websites. For more information, see Getting started.

Configure security settings to ensure secure logons to ECS instances

By default, a non-root account can be used to log on to an ECS instance. Before you can use a non-root account to log on to an ECS instance, you must run the su or sudo command on the instance to grant administrative permissions to the account. By default, you cannot use the root account with a key file in the PEM format to log on to the instance. We recommend that you use a secure access control protocol to access ECS instances and select different logon credentials based on image types. For Linux instances, we recommend that you configure the instances to support only RSA-encrypted key pairs as logon credentials and not to support passwords as logon credentials. For Windows instances, we recommend that you use complex passwords that are more than eight characters in length and contain special characters as logon credentials.

Encrypt data in transit

Configure security groups or firewalls to allow communication only between ports used by network services that encrypt data. You can use encryption protocols such as Transport Layer Security (TLS) 1.2 and later to encrypt sensitive data in transit between clients and ECS instances.

Monitor and audit log exceptions

The M-Trends 2018 report published by FireEye stated that most enterprises, especially enterprises in Asia Pacific, are vulnerable to cybersecurity attacks. The global median dwell time was 101 days. In Asia Pacific, the median dwell time was 498 days. The dwell time indicates a period from when an attack occurs to when the attack is detected. To shorten the dwell time, enterprises need reliable log data and audit services.