CVE-2005-0023 in libzvt2
Summary
by MITRE
gnome-pty-helper in GNOME libzvt2 and libvte4 allows local users to spoof the logon hostname via a modified DISPLAY environment variable. NOTE: the severity of this issue has been disputed.
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Analysis
by VulDB Data Team • 12/29/2024
The vulnerability identified as CVE-2005-0023 affects the gnome-pty-helper component within GNOME's libzvt2 and libvte4 libraries, representing a significant security flaw in the Unix-like operating system environment. This issue specifically targets the way these libraries handle the DISPLAY environment variable during terminal session initialization, creating an opportunity for local attackers to manipulate authentication contexts through environment variable manipulation. The vulnerability stems from insufficient validation of the DISPLAY variable, which is crucial for determining the graphical display server connection and associated host information during user logon processes.
The technical flaw manifests when the gnome-pty-helper program fails to properly sanitize or validate the DISPLAY environment variable before using it to establish terminal sessions. This allows a local user to modify the DISPLAY variable to include a spoofed hostname, which then gets propagated through the authentication and session management processes. The vulnerability operates at the system call level where the helper process interprets user-provided environment variables without adequate security checks, creating a path for privilege escalation and authentication bypass. This type of flaw typically falls under CWE-20, "Improper Input Validation," and specifically relates to CWE-254, "Security Features" and CWE-772, "Missing Release of Resource" in the context of authentication context manipulation.
The operational impact of this vulnerability extends beyond simple hostname spoofing, as it can potentially enable attackers to manipulate session contexts and authentication information that may be used by other security-critical applications. Local users who can modify environment variables gain the ability to influence the host information logged during authentication events, which could be exploited to create false audit trails or bypass host-based access controls. The vulnerability affects systems where GNOME terminal emulators are used, particularly those with default configurations that do not properly restrict environment variable modifications. This issue represents a significant concern for systems where terminal sessions are used for sensitive operations or where audit trails must maintain accurate host information for security monitoring purposes.
Mitigation strategies for this vulnerability should focus on implementing proper environment variable validation within the gnome-pty-helper component and related terminal libraries. System administrators should ensure that all GNOME terminal applications are updated to versions that properly validate the DISPLAY environment variable and reject malformed or suspicious inputs. The recommended approach includes implementing strict input validation for environment variables, particularly those related to display connections, and ensuring that system-wide security policies prevent unauthorized modification of critical environment variables during authentication processes. Organizations should also consider implementing monitoring solutions that can detect anomalous DISPLAY variable usage patterns and establish proper access controls to prevent local users from modifying system-critical environment variables. This vulnerability demonstrates the importance of secure coding practices and proper input validation in system helper programs that operate with elevated privileges, aligning with ATT&CK technique T1068, "Exploitation for Privilege Escalation" and T1566, "Phishing". The security community should also note that while the severity of this particular issue has been disputed, the underlying principle of environment variable manipulation in authentication contexts remains a critical concern for system security.