CVE-2018-14635 in openstack-neutron
Summary
by MITRE
When using the Linux bridge ml2 driver, non-privileged tenants are able to create and attach ports without specifying an IP address, bypassing IP address validation. A potential denial of service could occur if an IP address, conflicting with existing guests or routers, is then assigned from outside of the allowed allocation pool. Versions of openstack-neutron before 13.0.0.0b2, 12.0.3 and 11.0.5 are vulnerable.
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Analysis
by VulDB Data Team • 11/08/2024
The vulnerability described in CVE-2018-14635 represents a significant security flaw within the OpenStack Neutron networking service, specifically affecting the Linux bridge ml2 driver implementation. This issue stems from inadequate input validation mechanisms that allow unprivileged tenant users to create network ports without proper IP address specification, effectively bypassing the normal validation procedures that should enforce IP address allocation policies. The flaw exists in the network port creation process where the system fails to properly validate whether IP addresses are correctly assigned or whether they conflict with existing network resources, creating a potential pathway for malicious or unauthorized network manipulation.
The technical implementation of this vulnerability manifests through the Linux bridge ml2 driver's failure to enforce proper IP address validation during port creation operations. When tenants create network ports without specifying IP addresses, the system should typically validate these addresses against existing network configurations and allocation pools. However, this validation process is bypassed, allowing potentially conflicting IP addresses to be assigned to network ports. This weakness operates at the network layer where IP address management is handled, specifically within the neutron networking service that controls virtual network infrastructure in OpenStack environments. The vulnerability is categorized under CWE-20 as a "Bad Input Validation" issue, where the system fails to properly validate input parameters before processing them, and aligns with ATT&CK technique T1046 for Network Service Scanning and T1499 for Endpoint Denial of Service through network resource manipulation.
The operational impact of this vulnerability extends beyond simple configuration errors and can lead to serious network disruption and service availability issues. When non-privileged tenants create ports without proper IP address validation, they can potentially assign IP addresses that conflict with existing guests or router configurations, leading to network communication failures and service interruptions. The most significant concern arises when these conflicting IP addresses are assigned from outside the allowed allocation pools, creating scenarios where legitimate network services may become unreachable or where network traffic may be redirected to incorrect destinations. This situation can result in a denial of service condition affecting not just the specific tenant but potentially the entire network infrastructure, as IP address conflicts can cause routing tables to become corrupted and network connectivity to be severely compromised.
Organizations running affected versions of OpenStack Neutron, specifically those below 13.0.0.0b2, 12.0.3, and 11.0.5, face substantial risk of network-level attacks and service disruptions. The vulnerability enables a class of attacks where unauthorized users can manipulate network configurations to cause service degradation or complete network outages. Mitigation strategies should focus on immediate patching of affected systems to versions that properly enforce IP address validation during port creation operations. Additionally, network administrators should implement enhanced monitoring of port creation activities and IP address assignments to detect anomalous behavior that may indicate exploitation attempts. The fix addresses the root cause by implementing proper input validation that ensures all network ports created through the Linux bridge ml2 driver must undergo appropriate IP address validation before being attached to the network infrastructure, thereby preventing unauthorized or conflicting IP address assignments that could lead to denial of service conditions.