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🛡️ Google GCE Network allows unrestricted POP3 traffic🟢

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Logic​

Similar Policies​

  • Internal: dec-x-8a2089ff

Similar Internal Rules​

RulePoliciesFlags
✉️ dec-x-8a2089ff1

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 Post Office Protocol 3 (POP3) port, TCP/110.

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​

POP3 is a legacy email retrieval protocol that transmits both authentication credentials (usernames and passwords) and email content in cleartext. Exposing a POP3 service to the public internet introduces a severe security risk, as attackers can intercept or manipulate unencrypted traffic. Such exposure may result in credential theft, unauthorized mailbox access, and data compromise. To ensure secure email communication, POP3 should be replaced with more secure alternatives such as IMAP over SSL/TLS (IMAPS) or other encrypted email access methods.

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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 ranges.
  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
💼 APRA CPG 234 → 💼 36f network design — to ensure authorised network traffic flows and to reduce the impact of security compromises;76107no data
💼 APRA CPG 234 → 💼 45 An understanding of plausible worst case scenarios can help regulated entities identify and implement additional controls to prevent or reduce the impact of such scenarios. One example is malware that infects computers and encrypts data, both on the infected computer and any connected storage, including (corporate) networks and cloud storage. Such attacks reinforce the importance of protecting the backup environment in the event that the production environment is compromised. Common techniques to achieve this include network segmentation, highly restricted and segregated access controls and network traffic flow restrictions.83115no data
💼 Cloudaware Framework → 💼 Network Exposure137no data
💼 FedRAMP High Security Controls → 💼 AC-4(21) Physical or Logical Separation of Information Flows (M)(H)18141no data
💼 FedRAMP Moderate Security Controls → 💼 AC-4(21) Physical or Logical Separation of Information Flows (M)(H)141no data
💼 ISO/IEC 27001:2013 → 💼 A.13.1.1 Network controls65no data
💼 NIST CSF v1.1 → 💼 DE.AE-1: A baseline of network operations and expected data flows for users and systems is established and managed1179no data
💼 NIST CSF v1.1 → 💼 DE.CM-1: The network is monitored to detect potential cybersecurity events2165no data
💼 NIST CSF v1.1 → 💼 PR.AC-3: Remote access is managed66no data
💼 NIST CSF v1.1 → 💼 PR.AC-5: Network integrity is protected (e.g., network segregation, network segmentation)1184no data
💼 NIST CSF v1.1 → 💼 PR.DS-2: Data-in-transit is protected1797no data
💼 NIST CSF v1.1 → 💼 PR.DS-5: Protections against data leaks are implemented89152no data
💼 NIST CSF v1.1 → 💼 PR.PT-4: Communications and control networks are protected1184no data
💼 NIST CSF v2.0 → 💼 DE.CM-01: Networks and network services are monitored to find potentially adverse events187no data
💼 NIST CSF v2.0 → 💼 ID.AM-03: Representations of the organization's authorized network communication and internal and external network data flows are maintained128no data
💼 NIST CSF v2.0 → 💼 PR.AA-03: Users, services, and hardware are authenticated102no 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 duties199no data
💼 NIST CSF v2.0 → 💼 PR.AA-06: Physical access to assets is managed, monitored, and enforced commensurate with risk84no data
💼 NIST CSF v2.0 → 💼 PR.DS-01: The confidentiality, integrity, and availability of data-at-rest are protected248no data
💼 NIST CSF v2.0 → 💼 PR.DS-02: The confidentiality, integrity, and availability of data-in-transit are protected219no data
💼 NIST CSF v2.0 → 💼 PR.DS-10: The confidentiality, integrity, and availability of data-in-use are protected249no data
💼 NIST CSF v2.0 → 💼 PR.IR-01: Networks and environments are protected from unauthorized logical access and usage165no data
💼 NIST SP 800-53 Revision 4 → 💼 SC-7 BOUNDARY PROTECTION23531no data
💼 NIST SP 800-53 Revision 5 → 💼 AC-4(21) Information Flow Enforcement _ Physical or Logical Separation of Information Flows83141no data
💼 UK Cyber Essentials → 💼 1.2 Prevent access to the administrative interface from the internet85119no data