CVE-2008-6992 in GreenSQL Firewall
Summary
by MITRE
GreenSQL Firewall (greensql-fw), possibly before 0.9.2 or 0.9.4, allows remote attackers to bypass the SQL injection protection mechanism via a WHERE clause containing an expression such as "x=y=z", which is successfully parsed by MySQL.
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Analysis
by VulDB Data Team • 02/01/2025
The vulnerability identified as CVE-2008-6992 affects GreenSQL Firewall, a database security solution designed to protect against SQL injection attacks by filtering and monitoring SQL queries. This weakness exists in versions prior to 0.9.2 or 0.9.4 of the software, representing a critical flaw in the firewall's ability to properly validate and sanitize incoming SQL statements. The vulnerability specifically targets the SQL injection protection mechanism that GreenSQL Firewall employs to safeguard databases from malicious queries. The flaw allows attackers to craft SQL expressions that bypass the firewall's detection capabilities, effectively undermining the security controls that organizations rely upon to prevent unauthorized database access and data manipulation.
The technical root cause of this vulnerability lies in how GreenSQL Firewall processes and analyzes SQL query structures, particularly when encountering complex WHERE clauses with multiple equality comparisons. When an attacker submits a query containing expressions such as "x=y=z", the firewall fails to properly recognize this as a potentially malicious construct that could be exploited for SQL injection attacks. The vulnerability stems from insufficient parsing logic within the firewall's SQL analysis engine, which relies on overly simplistic pattern matching or structural analysis that does not account for legitimate SQL constructs that may appear suspicious to naive security systems. This particular SQL expression format demonstrates a bypass technique that exploits the firewall's inability to properly evaluate the semantic meaning of nested equality operations within WHERE clauses.
The operational impact of this vulnerability is severe as it allows remote attackers to circumvent the primary security controls designed to protect database systems from SQL injection attacks. An attacker can successfully execute malicious queries that would normally be blocked by the firewall, potentially gaining unauthorized access to sensitive data, modifying database contents, or even escalating privileges within the database environment. This vulnerability directly violates the fundamental security principle of defense in depth, as the firewall fails to provide the expected protection layer that organizations implement to secure their database infrastructure. The implications extend beyond simple data theft to include potential system compromise, data integrity violations, and compliance violations that organizations may face when database security controls are bypassed.
Organizations affected by this vulnerability should immediately upgrade to GreenSQL Firewall version 0.9.2 or 0.9.4, whichever is appropriate for their deployment environment, as these releases contain the necessary patches to address the parsing logic flaws. Additionally, system administrators should implement additional monitoring and logging mechanisms to detect anomalous SQL query patterns that may indicate exploitation attempts. The vulnerability aligns with CWE-117, which addresses improper output neutralization for logs, and relates to ATT&CK technique T1071.004 for application layer protocol, specifically targeting database communication protocols. Organizations should also consider implementing redundant security controls such as database activity monitoring, intrusion detection systems, and comprehensive database auditing to provide layered protection against similar bypass techniques. Security teams should conduct thorough vulnerability assessments to ensure that no other similar parsing or validation flaws exist within their database security infrastructure, as this vulnerability demonstrates the critical importance of proper SQL parsing and validation in database security solutions.