CVE-2006-6692 in Zabbix
Summary
by MITRE
Multiple format string vulnerabilities in zabbix before 20061006 allow attackers to cause a denial of service (application crash) and possibly execute arbitrary code via format string specifiers in information that would be recorded in the system log using (1) zabbix_log or (2) zabbix_syslog.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 01/27/2025
The vulnerability identified as CVE-2006-6692 represents a critical format string vulnerability affecting the Zabbix monitoring system prior to version 20061006. This issue stems from improper input validation within the system's logging mechanisms, specifically in how the zabbix_log and zabbix_syslog functions handle user-supplied data. The vulnerability manifests when these logging functions process information that contains format string specifiers, which are typically used to control output formatting in C programming languages. When maliciously crafted input containing these specifiers is processed through the logging functions, it creates opportunities for exploitation that can result in system instability and potential code execution.
The technical flaw resides in the application's failure to properly sanitize or escape user input before passing it to logging functions that use printf-style formatting. This creates a classic format string vulnerability where an attacker can inject format specifiers such as %x, %s, %n, or %p into the logging input. When the logging system processes these specifiers, they can cause the application to read from or write to arbitrary memory locations, leading to memory corruption and potential application crashes. The vulnerability affects both zabbix_log and zabbix_syslog functions, indicating a systemic issue within the logging infrastructure rather than isolated components. This design flaw allows attackers to manipulate the program's execution flow by controlling how memory is accessed during logging operations.
The operational impact of this vulnerability is significant, as it enables both denial of service and potential remote code execution capabilities. An attacker who can control input to the logging functions can cause the Zabbix application to crash and restart repeatedly, resulting in service disruption that can go unnoticed for extended periods. More critically, the format string vulnerability may allow for arbitrary code execution, giving attackers the ability to escalate privileges and gain unauthorized access to the monitoring system. This is particularly concerning for Zabbix systems, which often serve as critical infrastructure monitoring tools with access to sensitive network data and system information. The vulnerability's potential for remote exploitation means that attackers could compromise monitoring systems from external networks, potentially gaining insights into network topology, system configurations, and security posture.
Mitigation strategies for CVE-2006-6692 should focus on immediate patching of affected Zabbix installations to version 20061006 or later, which contains the necessary fixes for the format string vulnerabilities. Organizations should also implement input validation and sanitization measures to prevent malicious format specifiers from reaching the logging functions. The principle of least privilege should be enforced when configuring logging operations, ensuring that the Zabbix application runs with minimal required permissions and that log files are properly protected from unauthorized modification. Network segmentation and monitoring of logging system behavior can help detect exploitation attempts, while regular security audits should verify that no other similar vulnerabilities exist within the application's codebase. This vulnerability aligns with CWE-134, which specifically addresses format string vulnerabilities, and maps to ATT&CK technique T1059.007 for command and scripting interpreter, as exploitation may involve executing arbitrary code through the compromised logging functions.
The vulnerability demonstrates the critical importance of proper input validation in security-critical applications, particularly those handling user-supplied data in logging contexts. It serves as a reminder that even seemingly benign functions like logging can become attack vectors when proper security controls are not implemented. Organizations should establish robust code review processes that specifically examine logging and formatting functions for potential format string vulnerabilities, as these issues often persist in legacy codebases where security considerations may not have been fully implemented. Regular security assessments and penetration testing should include thorough examination of application logging mechanisms to identify and remediate similar vulnerabilities before they can be exploited in production environments.