CVE-2011-0729 in language-selector
Summary
by MITRE
dbus_backend/ls-dbus-backend in the D-Bus backend in language-selector before 0.6.7 does not restrict access on the basis of a PolicyKit check result, which allows local users to modify the /etc/default/locale and /etc/environment files via a (1) SetSystemDefaultLangEnv or (2) SetSystemDefaultLanguageEnv call.
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Analysis
by VulDB Data Team • 11/05/2021
The vulnerability identified as CVE-2011-0729 resides within the D-Bus backend implementation of the language-selector package in Ubuntu and related distributions. This flaw exists in versions prior to 0.6.7 and represents a critical authorization bypass that undermines the security controls designed to protect system locale configuration files. The D-Bus framework serves as a message bus system that enables communication between different applications and system services, making it a crucial component for desktop environment functionality and system management operations.
The technical flaw manifests in the dbus_backend/ls-dbus-backend module where the language-selector application fails to properly validate PolicyKit authorization checks before permitting modifications to critical system files. PolicyKit is an authorization framework that determines whether specific operations should be allowed based on user privileges and system policies. When local users invoke the SetSystemDefaultLangEnv or SetSystemDefaultLanguageEnv D-Bus methods, the system should verify that the requesting user possesses sufficient privileges to modify system-wide locale settings. However, this validation is bypassed, allowing unauthorized modification of sensitive configuration files.
This vulnerability creates a significant operational impact by enabling local privilege escalation within the context of system locale management. Attackers can exploit this weakness to modify the /etc/default/locale and /etc/environment files, which contain system-wide language and locale settings that affect the entire desktop environment and system services. The implications extend beyond simple configuration changes, as these files influence application behavior, system localization, and potentially create persistent backdoors or misconfigurations that could affect system stability and security posture.
The vulnerability aligns with CWE-284, which describes improper access control, and represents a clear violation of the principle of least privilege in system security design. From an attacker's perspective, this flaw provides an effective means of modifying system configuration without proper authorization, potentially leading to more severe consequences such as privilege escalation or system misconfiguration. The ATT&CK framework categorizes this as a privilege escalation technique through legitimate system tools, where an attacker leverages existing system services to gain unauthorized access to system resources.
Mitigation strategies should focus on immediate patching of affected systems to version 0.6.7 or later of the language-selector package. System administrators should also implement monitoring for unauthorized modifications to the /etc/default/locale and /etc/environment files, as well as ensure that appropriate file permissions and access controls are maintained on these critical system configuration files. Additional defensive measures include implementing mandatory access controls, regular security auditing of system services, and ensuring that all system components properly validate authorization checks before executing privileged operations. Organizations should also consider implementing application whitelisting policies to prevent unauthorized execution of potentially malicious code that could exploit similar authorization bypass vulnerabilities.