CVE-2014-8156 in fso-gsm
Summary
by MITRE
The D-Bus security policy files in /etc/dbus-1/system.d/*.conf in fso-gsmd 0.12.0-3, fso-frameworkd 0.9.5.9+git20110512-4, and fso-usaged 0.12.0-2 as packaged in Debian, the upstream cornucopia.git (fsoaudiod, fsodatad, fsodeviced, fsogsmd, fsonetworkd, fsotdld, fsousaged) git master on 2015-01-19, the upstream framework.git 0.10.1 and git master on 2015-01-19, phonefsod 0.1+git20121018-1 as packaged in Debian, Ubuntu and potentially other packages, and potentially other fso modules do not properly filter D-Bus message paths, which might allow local users to cause a denial of service (dbus-daemon memory consumption), or execute arbitrary code as root by sending a crafted D-Bus message to any D-Bus system service.
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Analysis
by VulDB Data Team • 11/19/2019
The vulnerability described in CVE-2014-8156 represents a critical security flaw in the D-Bus security policy implementation within the Free Software Foundation (FSO) telephony stack components. This issue affects multiple FSO modules including fso-gsmd, fso-frameworkd, and fso-usaged, which are commonly packaged in Debian, Ubuntu, and other Linux distributions. The vulnerability stems from improper filtering of D-Bus message paths in system policy files located at /etc/dbus-1/system.d/*.conf, creating a pathway for malicious actors to exploit the underlying D-Bus daemon infrastructure. The flaw specifically manifests when these policy files fail to adequately validate or sanitize the message paths that are processed by the D-Bus system bus, allowing unauthorized access to privileged services.
The technical implementation of this vulnerability exploits the fundamental architecture of D-Bus security mechanisms, where policy files define which services can receive messages and what operations they can perform. When these policy files do not properly filter D-Bus message paths, they create opportunities for attackers to craft malicious messages that can bypass intended access controls. The flaw enables attackers to send specially crafted D-Bus messages that target system services, potentially causing the dbus-daemon process to consume excessive memory resources leading to denial of service conditions. More critically, the vulnerability can be leveraged to execute arbitrary code with root privileges, as the improperly filtered paths allow attackers to gain unauthorized access to services that should only be accessible by the system administrator or specific privileged processes.
The operational impact of CVE-2014-8156 is severe and multifaceted, affecting both system availability and integrity. Local attackers can exploit this vulnerability to cause denial of service by consuming excessive memory resources within the dbus-daemon process, potentially leading to system instability or complete service unavailability. However, the more dangerous aspect involves privilege escalation, where attackers can execute arbitrary code as root, effectively compromising the entire system. This vulnerability is particularly concerning in embedded systems and mobile devices where FSO components are commonly deployed, as these environments often lack additional security layers that might otherwise protect against such exploits. The impact extends beyond individual systems to potentially affect entire device fleets in managed environments where multiple devices share similar configurations.
The vulnerability aligns with CWE-22 (Improper Limitation of a Pathname to a Restricted Directory) and CWE-264 (Permissions, Privileges, and Access Controls) classifications, representing a combination of path traversal issues and access control bypass mechanisms. From an ATT&CK framework perspective, this vulnerability maps to T1068 (Exploitation for Privilege Escalation) and T1499.004 (Endpoint Denial of Service) techniques, demonstrating how improper input validation can lead to both privilege escalation and service disruption. The attack surface is particularly wide given that the vulnerability affects multiple FSO modules and is present in various distribution packages, making it a significant concern for system administrators maintaining telephony and mobile device infrastructure. Organizations should prioritize patching affected systems and implementing additional monitoring for anomalous D-Bus activity, as the vulnerability can be exploited without requiring network access or specialized privileges beyond local system access.
Mitigation strategies should focus on updating to patched versions of the affected FSO components, implementing proper D-Bus policy file validation, and establishing monitoring for suspicious D-Bus message patterns. System administrators should also consider implementing additional access controls and privilege separation measures to limit the impact of potential exploitation. The vulnerability underscores the importance of proper security policy implementation in distributed messaging systems and highlights the critical need for thorough testing of security configurations in complex software ecosystems.