CVE-2006-2220 in phpBB
Summary
by MITRE
phpBB 2.0.20 does not properly verify user-specified input variables used as limits to SQL queries, which allows remote attackers to obtain sensitive information via a negative LIMIT specification, as demonstrated by the start parameter to memberlist.php, which reveals the SQL query in the resulting error message.
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Analysis
by VulDB Data Team • 08/19/2018
The vulnerability described in CVE-2006-2220 represents a classic SQL injection weakness within the phpBB 2.0.20 bulletin board system that stems from inadequate input validation mechanisms. This flaw exists in the application's handling of user-supplied parameters that are directly incorporated into SQL query construction without proper sanitization or range checking. The specific vulnerability manifests when the application processes the start parameter in memberlist.php, which is used to control pagination of user listings. Attackers can manipulate this parameter to include negative values that bypass normal input validation checks, enabling them to craft malicious SQL queries that exploit the application's insufficient parameter verification.
The technical exploitation of this vulnerability leverages the fundamental principle of SQL injection attacks where user-controllable input is improperly handled within database query construction. When phpBB processes the start parameter without validating that it represents a legitimate positive integer, attackers can submit negative values that cause the database to return error messages containing the actual SQL query structure. This occurs because most database systems will process negative LIMIT clauses by throwing errors that reveal internal query details. The vulnerability specifically maps to CWE-129 Input Validation and CWE-89 SQL Injection, representing a failure in both input sanitization and parameter handling. The ATT&CK framework categorizes this under T1190 Exploit Public-Facing Application, as it targets a web application component that is accessible from external networks.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with detailed insights into the application's database structure and query patterns. The error messages that reveal SQL queries can expose table names, column structures, and potentially sensitive data elements that would otherwise remain hidden. This information can be leveraged by attackers to plan more sophisticated attacks against the same application or to develop additional exploitation techniques. The vulnerability affects the confidentiality and integrity of the system, as it allows unauthorized access to database query structures that could be used to infer sensitive information about user data and system architecture. Organizations running vulnerable phpBB installations face significant risk of data exposure and potential further compromise if attackers can use this information to identify additional vulnerabilities.
The recommended mitigations for this vulnerability include implementing proper input validation and sanitization for all user-supplied parameters that are used in database queries. Applications should enforce strict type checking and range validation, ensuring that numeric parameters like the start parameter are validated as positive integers before being used in SQL operations. The phpBB development team addressed this issue by implementing proper parameter validation in subsequent releases, requiring that pagination parameters be validated against expected ranges and sanitized before database processing. Organizations should also implement proper error handling that does not expose database query details to end users, and should apply security patches immediately upon release. Additional defensive measures include implementing web application firewalls, database query monitoring, and regular security assessments to identify similar input validation weaknesses across all application components. The vulnerability demonstrates the critical importance of input validation in preventing SQL injection attacks and highlights the necessity of following secure coding practices that align with industry standards such as those defined by the Open Web Application Security Project OWASP.