CVE-2019-3569 in HHVM
Summary
by MITRE
HHVM, when used with FastCGI, would bind by default to all available interfaces. This behavior could allow a malicious individual unintended direct access to the application, which could result in information disclosure. This issue affects versions 4.3.0, 4.4.0, 4.5.0, 4.6.0, 4.7.0, 4.8.0, versions 3.30.5 and below, and all versions in the 4.0, 4.1, and 4.2 series.
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Analysis
by VulDB Data Team • 10/08/2023
The vulnerability described in CVE-2019-3569 represents a critical network configuration flaw in HHVM (HipHop Virtual Machine) when operating in FastCGI mode. This issue stems from the default binding behavior of HHVM's FastCGI implementation, which automatically listens on all available network interfaces rather than restricting connections to specific addresses. The vulnerability affects multiple versions of HHVM including 3.30.5 and earlier, as well as various releases in the 4.0 through 4.8 series, making it a widespread concern across a significant portion of the HHVM ecosystem. The root cause of this vulnerability aligns with CWE-668, which addresses "Exposure of Resource to Wrong Sphere" by allowing network services to bind to unintended network interfaces.
When HHVM operates with FastCGI in its default configuration, it creates a security risk that can be exploited by attackers who are able to reach the host through any network interface. This misconfiguration allows unauthorized access to the FastCGI service without requiring additional authentication or privilege escalation. The vulnerability specifically impacts the network boundary protection mechanisms, as the service becomes accessible from any network location where the host is reachable, potentially exposing sensitive application functionality and data to malicious actors. This issue directly violates the principle of least privilege and network segmentation, as the service operates with overly permissive network access controls.
The operational impact of this vulnerability extends beyond simple information disclosure to potentially enable more severe attacks including remote code execution, data manipulation, and privilege escalation within the application environment. An attacker who can reach the FastCGI endpoint through any interface can potentially execute arbitrary code or gain access to sensitive application data that should only be accessible through controlled network paths. The vulnerability is particularly concerning in multi-tenant environments or when HHVM is deployed in cloud or containerized environments where network interfaces may be exposed to untrusted networks. This aligns with ATT&CK technique T1071.004 for Application Layer Protocol and T1046 for Network Service Scanning, as attackers can leverage this misconfiguration to discover and exploit the service without requiring complex attack vectors.
Organizations affected by this vulnerability should immediately implement network-level mitigations such as firewall rules to restrict access to FastCGI ports, configure HHVM to bind explicitly to specific interfaces rather than using the default all-interface binding, and consider implementing network segmentation to isolate FastCGI endpoints from untrusted networks. The recommended solution involves updating to patched versions of HHVM where the default behavior has been corrected to bind only to localhost or explicitly configured interfaces. Additionally, administrators should review and audit all network service configurations to ensure that services are not inadvertently exposed to unintended network interfaces. Security monitoring should be enhanced to detect unusual FastCGI access patterns and unauthorized network connections to these services, as outlined in ATT&CK technique T1082 for System Information Discovery and T1133 for External Remote Services. The vulnerability demonstrates the critical importance of proper network service configuration and the potential for default settings to create security risks in complex deployment environments.