CVE-2006-3855 in Informix Dynamic Server
Summary
by MITRE
The ifx_load_internal function in IBM Informix Dynamic Server (IDS) allows remote authenticated users to execute arbitrary C code via the DllMain or _init function in a library, aka "C code UDR."
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Analysis
by VulDB Data Team • 06/24/2019
The vulnerability identified as CVE-2006-3855 represents a critical security flaw in IBM Informix Dynamic Server version 11.50 and earlier releases. This issue affects the ifx_load_internal function which is responsible for loading dynamic libraries within the database system. The vulnerability specifically targets the handling of shared libraries during the loading process, creating an execution path that allows authenticated remote attackers to inject and execute arbitrary C code within the context of the database server. The flaw is particularly dangerous because it enables attackers to leverage User Defined Routines (UDRs) as a means of code execution, bypassing normal security boundaries that should protect the database server from external code injection.
The technical implementation of this vulnerability stems from improper validation and handling of dynamic library loading mechanisms within IDS. When the ifx_load_internal function processes library loading requests, it fails to properly sanitize or validate the input parameters that specify which libraries to load. This deficiency creates a path where an authenticated user can craft malicious library files containing DllMain or _init functions that execute arbitrary code when loaded into the database process. The vulnerability operates at the system level where the database server process loads these libraries, effectively allowing attackers to execute code with the privileges of the database service account, which typically has extensive system access rights.
The operational impact of CVE-2006-3855 extends beyond simple code execution, as it can lead to complete system compromise when combined with proper authentication. Attackers who can authenticate to the database system can leverage this vulnerability to escalate privileges, access sensitive data, modify database contents, or establish persistent backdoors. The remote execution capability means that attackers do not need physical access to the server, making this vulnerability particularly attractive for network-based attacks. The vulnerability also impacts database integrity and availability since malicious code execution can corrupt database files or consume system resources. This weakness aligns with CWE-242, which describes the vulnerability of using potentially insecure functions that can lead to code execution, and represents a clear violation of the principle of least privilege in database security.
Organizations affected by this vulnerability should implement immediate mitigations including applying the latest security patches from IBM, which typically involve updating the IDS software to versions that properly validate library loading operations. Network segmentation and access controls should be strengthened to limit authentication access to database systems, particularly for users who do not require full administrative privileges. Monitoring should be enhanced to detect unusual library loading activities or attempts to execute code within database processes. The vulnerability also highlights the importance of following secure coding practices and conducting regular security assessments of database systems. According to ATT&CK framework, this vulnerability maps to T1059.007 for "Command and Scripting Interpreter: Python" and T1068 for "Exploitation for Privilege Escalation" while also covering T1546.008 for "Exploitation for Privilege Escalation" through DLL side-loading techniques. Organizations should also consider implementing database activity monitoring solutions that can detect anomalous behavior patterns associated with library loading and code execution within database environments.