Use the Conformity Knowledge Base AI to help improve your Cloud Posture

Check for Unrestricted Memcached Access

Trend Cloud One™ – Conformity is a continuous assurance tool that provides peace of mind for your cloud infrastructure, delivering over 1000 automated best practice checks.

Risk Level: High (not acceptable risk)

Ensure that Google Cloud VPC network firewall rules do not allow unrestricted access (i.e. 0.0.0.0/0) on TCP and/or UDP port 11211 in order to reduce the attack surface and protect the Memcached cache server instances associated with your firewall rules. Memcached is an open source, high-performance, distributed memory object caching system, intended for use in speeding up dynamic websites and web applications by alleviating database load.

Security

Allowing unrestricted access on TCP and/or UDP port 11211 to your virtual machine instances through VPC network firewall rules can increase opportunities for malicious activities such as DDoS amplification attacks, which can have a serious impact on the health and stability of your web services and applications. VPC firewall rules should be configured so that access to specific resources is restricted to just those hosts or networks that have a legitimate business requirement for access.


Audit

To determine if your Google Cloud VPC firewall rules allow unrestricted Memcached access, perform the following operations:

Using GCP Console

01 Sign in to Google Cloud Management Console.

02 Select the Google Cloud Platform (GCP) project that you want to examine from the console top navigation bar.

03 Navigate to VPC Network console available at https://console.cloud.google.com/networking.

04 In the navigation panel, select Firewall to access the VPC firewall rules defined for the selected GCP project.

05 In the VPC firewall rules section, click inside the Filter box, set Type to Ingress and Disabled to False, to list all the active inbound firewall rules created for your cloud resources.

06 Check the filtered list for any inbound rules with the Protocols / ports attribute set to tcp:11211 or tcp:0-65535, udp:11211, or udp:0-65535, Action set to Allow, and Filters set to IP ranges: 0.0.0.0/0. If one or more rules match the filter criteria, there are VPC network firewall rules that allow unrestricted access on TCP and/or UDP port 11211, therefore, the Memcached service access to the associated cloud resources is not secured.

07 Repeat steps no. 3 – 6 for each GCP project deployed in your Google Cloud account.

Using GCP CLI

01 Run projects list command (Windows/macOS/Linux) using custom query filters to list the IDs of the Google Cloud Platform (GCP) projects currently available within your cloud account:

gcloud projects list
  --format="table(projectId)"

02 The command output should return the requested GCP project identifiers (IDs):

PROJECT_ID
cc-project5-stack-123123
cc-ad-platform-stack-112233

03 Run compute networks list command (Windows/macOS/Linux) using the ID of the GCP project that you want to examine as the identifier parameter and custom query filters to describe the name of each VPC network created within the selected project:

gcloud compute networks list
  --project cc-project5-stack-123123
  --format="table(name)"

04 The command output should return the name(s) of the VPC network(s) created for the specified project:

NAME
cc-web-stack-network

05 Run compute firewall-rules list command (Windows/macOS/Linux) using the name of the VPC network that you want to examine as the identifier parameter and custom filtering to list all the firewall rules defined for the selected Virtual Private Cloud (VPC):

gcloud compute firewall-rules list
  --filter network=cc-web-stack-network
  --sort-by priority
  --format=table"(name,disabled,direction,sourceRanges,allowed[].map().firewall_rule().list())"

06 The command output should return the information available for the existing VPC firewall rules:

NAME: cc-web-allow-http
DISABLED: False
DIRECTION: INGRESS
SOURCE_RANGES: ['0.0.0.0/0']
ALLOW: tcp:80

NAME: cc-web-allow-https
DISABLED: False
DIRECTION: INGRESS
SOURCE_RANGES: ['0.0.0.0/0']
ALLOW: tcp:443

NAME: cc-web-allow-memcached
DISABLED: False
DIRECTION: INGRESS
SOURCE_RANGES: ['0.0.0.0/0']
ALLOW: tcp:11211

Check the compute firewall-rules list command output for any active firewall rules (i.e. DISABLED: False) with the DIRECTION set to INGRESS, SOURCE_RANGES set to ['0.0.0.0/0'], and ALLOW set to tcp:11211 or tcp:0-65535, udp:11211 or udp:0-65535. If one or more rules match the search criteria, there are VPC network firewall rules that allow unrestricted access on TCP and/or UDP port 11211, therefore, the Memcached service access to the associated cloud resources is not restricted or secured.

07 Repeat steps no. 5 and 6 for each VPC network created for the selected GCP project.

08 Repeat steps no. 3 – 7 for each GCP project deployed in your Google Cloud account.

Remediation / Resolution

To update your VPC network firewall rules configuration in order to restrict Memcached access to trusted entities only (i.e. authorized IP addresses or IP ranges), perform the following operations:

Using GCP Console

01 Sign in to Google Cloud Management Console.

02 Select the Google Cloud Platform (GCP) project that you want to examine from the console top navigation bar.

03 Navigate to VPC Network console available at https://console.cloud.google.com/networking.

04 In the navigation panel, select Firewall to access the VPC firewall rules defined for the selected GCP project.

05 In the VPC firewall rules section, click inside the Filter box, set Type to Ingress and Disabled to False, to list all the active inbound firewall rules created for your cloud resources.

06 Click on the name (link) of the firewall rule that allows unrestricted inbound access on TCP/UDP port 11211 and choose EDIT from the console top menu.

07 On the selected firewall rule configuration page, perform the following actions:

  1. Remove the non-compliant 0.0.0.0/0 IP address range from the Source IPv4 ranges configuration box to deny unrestricted (public) inbound access on TCP/UDP port 11211.
  2. Type the source IP address(es) or IP address range(s) into the Source IPv4 ranges box to define the source for the incoming traffic on TCP/UDP port 11211. The allowed IP address blocks must be specified in CIDR format (e.g. 192.168.10.0/24). The IP range(s) can include addresses inside your VPC network and outside your network. Source IP range(s) can be used to define sources both inside and outside Google Cloud Platform (GCP).
  3. Choose SAVE to apply the configuration changes.

08 If required, repeat steps no. 6 and 7 to configure other VPC network firewall rules that allow unrestricted inbound access on TCP/UDP port 11211 (Memcached).

09 Repeat steps no. 2 – 8 for each GCP project available within your Google Cloud account.

Using GCP CLI

01 Run compute firewall-rules update command (Windows/macOS/Linux) to update the VPC firewall rule that allows unrestricted inbound access on TCP port 11211, by replacing the non-compliant 0.0.0.0/0 IP source range with a trusted, authorized IP address/IP range. For the UDP protocol replace tcp:11211 with udp:11211 in the --allow parameter value. The IP range(s) can include addresses available within your VPC network and outside your network. The allowed IP address blocks must be defined in CIDR format. You can specify a single value (e.g. 192.168.10.0/24) or a comma-separated list of multiple values (e.g. 192.168.10.0/32, 192.168.10.0/24):

gcloud compute firewall-rules update cc-web-allow-memcached
  --allow tcp:11211
  --source-ranges=192.168.10.0/24
  --description="Allows Memcached access from authorized IPv4 address range"

02 The command output should return the ID of the configured VPC firewall rule:

Updated [https://www.googleapis.com/compute/v1/projects/cc-project5-stack-123123/global/firewalls/cc-web-allow-memcached].

03 If required, repeat steps no. 1 and 2 to configure other VPC network firewall rules that allow unrestricted inbound access on TCP/UDP port 11211 (Memcached).

04 Repeat steps no. 1 – 3 for each GCP project deployed in your Google Cloud account.

References

Publication date May 6, 2024