CVE-2007-5682 in TikiWiki
Summary
by MITRE
Incomplete blacklist vulnerability in tiki-graph_formula.php in TikiWiki before 1.9.8.2 allows remote attackers to execute arbitrary code by using variable functions and variable variables to write variables whose names match the whitelist, a different vulnerability than CVE-2007-5423.
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Analysis
by VulDB Data Team • 07/31/2019
The vulnerability described in CVE-2007-5682 represents a critical security flaw in TikiWiki versions prior to 1.9.8.2, specifically within the tiki-graph_formula.php component. This issue constitutes an incomplete blacklist security mechanism that fails to properly validate user input, creating a pathway for remote code execution attacks. The vulnerability exploits the application's handling of variable functions and variable variables, which are PHP features that allow dynamic variable naming and function calls based on string values. When attackers craft malicious input that matches patterns in the whitelist, they can manipulate the application's variable assignment mechanisms to execute arbitrary code on the server.
The technical exploitation of this vulnerability relies on the improper implementation of access control measures within TikiWiki's graph formula processing functionality. Attackers can leverage PHP's variable variables feature to dynamically create variable names that correspond to whitelisted patterns, effectively bypassing the intended security restrictions. This approach differs from the related CVE-2007-5423 vulnerability, which involved different exploitation techniques. The flaw demonstrates a classic insecure input handling pattern where the system attempts to filter dangerous inputs through a whitelist approach but fails to account for the dynamic nature of PHP's variable resolution mechanisms. This vulnerability aligns with CWE-20, which describes improper input validation, and specifically relates to CWE-94, which addresses the execution of arbitrary code through the use of dynamic code generation.
The operational impact of this vulnerability is severe as it allows remote attackers to gain full control over affected TikiWiki installations without requiring authentication. Once exploited, attackers can execute arbitrary commands on the server, potentially leading to complete system compromise, data exfiltration, and further lateral movement within network environments. The vulnerability affects organizations using TikiWiki for content management, collaboration platforms, and wiki-based applications where the graph formula functionality is enabled. This threat is particularly concerning given that TikiWiki is widely used in enterprise environments for collaborative document management and knowledge sharing platforms.
Mitigation strategies for this vulnerability include immediate patching of TikiWiki installations to version 1.9.8.2 or later, which contains the necessary fixes for the incomplete blacklist implementation. Organizations should also implement network-level restrictions to limit access to the affected component, disable unnecessary functionality where possible, and conduct thorough security reviews of input validation mechanisms throughout the application. The remediation process should include implementing proper parameter validation and sanitization, avoiding the use of dynamic variable assignment with user-provided data, and employing a whitelist-based approach that validates against a comprehensive and restrictive set of allowed characters and patterns. This vulnerability demonstrates the importance of proper input validation and the dangers of relying solely on incomplete filtering mechanisms, aligning with ATT&CK technique T1059.007 for command and script injection attacks. Organizations should also consider implementing web application firewalls and monitoring systems to detect potential exploitation attempts and maintain comprehensive logging of user activities within the application.