CVE-2019-3789 in Cloud Foundry
Summary
by MITRE
Cloud Foundry Routing Release, all versions prior to 0.188.0, contains a vulnerability that can hijack the traffic to route services hosted outside the platform. A user with space developer permissions can create a private domain that shadows the external domain of the route service, and map that route to an app. When the gorouter receives traffic destined for the external route service, this traffic will instead be directed to the internal app using the shadow route.
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Analysis
by VulDB Data Team • 06/02/2020
The vulnerability identified as CVE-2019-3789 affects Cloud Foundry Routing Release versions prior to 0188.0 and represents a significant security flaw in the platform's routing mechanism that enables unauthorized traffic redirection. This issue specifically targets the routing logic within Cloud Foundry's infrastructure, where the system fails to properly validate domain ownership and routing precedence when handling external route services. The vulnerability stems from a lack of proper domain validation that allows malicious actors to exploit the routing system's trust model, creating a scenario where legitimate external services can be hijacked through improper route mapping.
The technical implementation of this vulnerability exploits the fundamental trust relationship between internal and external domains within Cloud Foundry's routing architecture. When a user with space developer permissions creates a private domain that mirrors an external domain used by route services, the system's routing logic fails to distinguish between legitimate external services and maliciously created shadow routes. This flaw operates at the core of Cloud Foundry's routing decision-making process, where the gorouter component does not properly enforce domain ownership boundaries. The vulnerability is classified under CWE-284, which deals with inadequate access control mechanisms, and represents a privilege escalation issue that allows users with limited permissions to effectively take control of traffic destined for external services.
The operational impact of CVE-2019-3789 extends beyond simple traffic redirection, potentially enabling sophisticated attack scenarios including man-in-the-middle attacks, data interception, and service disruption. An attacker could leverage this vulnerability to redirect traffic intended for critical external route services such as authentication endpoints, payment processing systems, or monitoring services to malicious applications they control. The implications are particularly severe in multi-tenant environments where multiple organizations share the same Cloud Foundry platform, as a single malicious user could compromise the routing of services belonging to other tenants. This vulnerability effectively undermines the security boundaries that Cloud Foundry attempts to establish between internal applications and external services, creating a pathway for lateral movement and data exfiltration.
The attack vector for this vulnerability requires minimal privileges, specifically space developer permissions, making it particularly dangerous in environments where these permissions are granted more broadly than necessary. According to ATT&CK framework, this vulnerability maps to T1071.004 for application layer protocol: DNS and T1566 for credential access through service hijacking, as attackers can effectively hijack legitimate service communications. Organizations should implement immediate mitigations including upgrading to Cloud Foundry Routing Release 0.188.0 or later, enforcing stricter domain validation policies, and implementing network segmentation controls. Additionally, monitoring for unauthorized domain creation and route mapping activities should be enhanced, as this vulnerability can be used to establish persistent access points for further attacks. The remediation process must also include comprehensive security reviews of existing route service configurations to identify and eliminate any shadow domains that may have already been established by malicious actors.