CVE-2018-1632 in Informix Dynamic Server Enterprise Edition
Summary
by MITRE
IBM Informix Dynamic Server Enterprise Edition 12.1 could allow a local user logged in with database administrator user to gain root privileges through a symbolic link vulnerability in .infxdirs. IBM X-Force ID: 144432.
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Analysis
by VulDB Data Team • 11/27/2023
The vulnerability identified as CVE-2018-1632 affects IBM Informix Dynamic Server Enterprise Edition version 12.1 and represents a critical privilege escalation flaw that enables local database administrators to elevate their privileges to root level access. This security weakness stems from improper handling of symbolic links within the .infxdirs directory structure, creating a path traversal scenario that can be exploited by maliciously crafted symbolic links. The vulnerability specifically impacts systems where database administrators have local login access, making it particularly concerning for environments where administrative privileges are shared across multiple users or where privilege separation is not properly enforced.
The technical flaw resides in the way Informix processes the .infxdirs file during database initialization and operation. When a database administrator logs into the system and the Informix server starts, the system attempts to process symbolic links within the .infxdirs directory to determine configuration parameters and directory locations. This processing does not adequately validate or sanitize symbolic link targets, allowing an attacker with database administrator privileges to create malicious symbolic links that point to sensitive system files or directories. The vulnerability operates under CWE-59, which classifies the weakness as "Improper Link Resolution" and falls within the broader category of path traversal attacks. The flaw essentially allows an attacker to manipulate the server's interpretation of directory locations, potentially causing the system to execute code or access files with elevated privileges.
The operational impact of this vulnerability is severe and multifaceted, particularly in enterprise environments where database administrators often possess significant system access. An attacker with database administrator privileges can leverage this vulnerability to gain root access, effectively bypassing all traditional privilege boundaries and gaining complete control over the underlying operating system. This escalation allows for unrestricted access to all system resources, including the ability to read sensitive data, modify system configurations, install malicious software, and potentially compromise other systems within the network. The vulnerability's local nature means that exploitation requires only a database administrator account, which is often less protected than system administrator accounts, making the attack surface broader than initially apparent.
Mitigation strategies for CVE-2018-1632 should focus on both immediate remediation and long-term architectural improvements. The primary recommendation is to apply the official IBM security patches and updates that address this specific vulnerability, which typically involve modifying how symbolic links are processed during server initialization. Organizations should also implement strict file permission controls and directory validation mechanisms to prevent unauthorized symbolic link creation in critical system directories. Network segmentation and privilege separation practices should be enhanced to ensure that database administrator accounts do not have unnecessary local system access. Additionally, monitoring and logging should be implemented to detect suspicious symbolic link creation activities, particularly in the .infxdirs directory. This vulnerability aligns with ATT&CK technique T1068 which covers "Exploitation for Privilege Escalation" and specifically addresses the use of local system vulnerabilities to gain elevated privileges. Organizations should also consider implementing principle of least privilege models where database administrators have minimal necessary access to system resources, reducing the potential impact of such privilege escalation attacks.