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🛡️ Google GCE Network allows unrestricted FTP traffic🟢

Logic​

Description​

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Description​

This policy identifies Google GCE Networks that have Firewall Rules allowing unrestricted incoming traffic (0.0.0.0/0) from the internet to the standard FTP ports: TCP/20 (data) and TCP/21 (control).

In GCP, Firewall Rules are defined at the VPC Network level. Each rule either allows or denies traffic based on its configuration. These configurations specify the type of traffic (e.g., protocols and ports) and the source or destination (e.g., IP addresses, subnets, and instances).

Rationale​

File Transfer Protocol (FTP) is a legacy protocol that transmits data, including usernames and passwords, in cleartext. Exposing FTP servers to the public internet creates significant security risks, including credential theft via network sniffing, brute-force attacks, and unauthorized access. Such exposure can result in data exfiltration, unauthorized file uploads, or compromise of internal resources.

Impact​

All FTP connections from outside the affected VPC(s) can be blocked. If there is a legitimate business requirement for remote access, specific trusted source IP addresses should be explicitly defined in firewall rules to whitelist access only to the required FTP ports.

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Remediation​

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Remediation​

From Google Cloud Console​

  1. Go to VPC Network.
  2. Go to the Firewall Rules.
  3. Click the Firewall Rule to be modified.
  4. Click Edit.
  5. Modify Source IP ranges to specific IP.
  6. Click Save.

From Google Cloud CLI​

  1. Identify Firewall Rules Allowing Public Access

    gcloud compute networks get-effective-firewalls default \
        --format="table(NAME, DIRECTION, IP_RANGES)" \
        --filter="IP_RANGES:0.0.0.0/0 AND DIRECTION:INGRESS"

  2. Restrict the Source Range

    Once you have identified the firewall rules, update each one to restrict access to trusted CIDR ranges:

    gcloud compute firewall-rules update {{firewall-rule-name}} \
        --source-ranges={{cidr-range1}},{{cidr-range2}}

policy.yaml​

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Linked Framework Sections​

SectionSub SectionsInternal RulesPoliciesFlagsCompliance
💼 Cloudaware Framework → 💼 Public and Anonymous Access101no data
💼 ISO/IEC 27001:2013 → 💼 A.13.1.1 Network controls21no data
💼 NIST CSF v1.1 → 💼 DE.AE-1: A baseline of network operations and expected data flows for users and systems is established and managed1034no data
💼 NIST CSF v1.1 → 💼 DE.CM-1: The network is monitored to detect potential cybersecurity events1863no data
💼 NIST CSF v1.1 → 💼 PR.AC-3: Remote access is managed22no data
💼 NIST CSF v1.1 → 💼 PR.AC-5: Network integrity is protected (e.g., network segregation, network segmentation)1044no data
💼 NIST CSF v1.1 → 💼 PR.DS-2: Data-in-transit is protected1653no data
💼 NIST CSF v1.1 → 💼 PR.DS-5: Protections against data leaks are implemented4791no data
💼 NIST CSF v1.1 → 💼 PR.PT-4: Communications and control networks are protected1044no data
💼 NIST CSF v2.0 → 💼 DE.CM-01: Networks and network services are monitored to find potentially adverse events145no data
💼 NIST CSF v2.0 → 💼 ID.AM-03: Representations of the organization's authorized network communication and internal and external network data flows are maintained69no data
💼 NIST CSF v2.0 → 💼 PR.AA-03: Users, services, and hardware are authenticated53no data
💼 NIST CSF v2.0 → 💼 PR.AA-05: Access permissions, entitlements, and authorizations are defined in a policy, managed, enforced, and reviewed, and incorporate the principles of least privilege and separation of duties116no data
💼 NIST CSF v2.0 → 💼 PR.AA-06: Physical access to assets is managed, monitored, and enforced commensurate with risk44no data
💼 NIST CSF v2.0 → 💼 PR.DS-01: The confidentiality, integrity, and availability of data-at-rest are protected148no data
💼 NIST CSF v2.0 → 💼 PR.DS-02: The confidentiality, integrity, and availability of data-in-transit are protected125no data
💼 NIST CSF v2.0 → 💼 PR.DS-10: The confidentiality, integrity, and availability of data-in-use are protected142no data
💼 NIST CSF v2.0 → 💼 PR.IR-01: Networks and environments are protected from unauthorized logical access and usage95no data
💼 NIST SP 800-53 Revision 4 → 💼 SC-7 BOUNDARY PROTECTION23531no data
💼 PCI DSS v3.2.1 → 💼 1.2.1 Restrict inbound and outbound traffic to that which is necessary for the cardholder data environment, and specifically deny all other traffic.1056no data
💼 PCI DSS v4.0.1 → 💼 1.3.1 Inbound traffic to the CDE is restricted.56no data
💼 PCI DSS v4.0.1 → 💼 1.3.2 Outbound traffic from the CDE is restricted.56no data
💼 PCI DSS v4.0 → 💼 1.3.1 Inbound traffic to the CDE is restricted.756no data
💼 PCI DSS v4.0 → 💼 1.3.2 Outbound traffic from the CDE is restricted.56no data