CVE-2008-6741 in Simple Machines
Summary
by MITRE
SQL injection vulnerability in Load.php in Simple Machines Forum (SMF) 1.1.4 and earlier allows remote attackers to execute arbitrary SQL commands by setting the db_character_set parameter to a multibyte character set such as big5, which causes the addslashes PHP function to produce a "\" (backslash) sequence that does not quote the " " (single quote) character, as demonstrated via a manlabels action to index.php.
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Analysis
by VulDB Data Team • 10/28/2024
The CVE-2008-6741 vulnerability represents a critical SQL injection flaw within Simple Machines Forum version 1.1.4 and earlier releases, specifically targeting the Load.php component. This vulnerability exploits a fundamental weakness in input validation and character set handling that allows remote attackers to bypass security measures and execute malicious SQL commands. The flaw manifests when the db_character_set parameter is manipulated to utilize multibyte character sets such as big5, creating a scenario where standard escaping mechanisms fail to properly sanitize user input. The vulnerability operates through a specific attack vector involving the manlabels action within index.php, demonstrating how seemingly benign configuration parameters can become entry points for sophisticated database exploitation.
The technical core of this vulnerability lies in the improper handling of multibyte character sets within PHP's addslashes function, which is a common defense mechanism against SQL injection attacks. When SMF processes the db_character_set parameter with multibyte encodings, the addslashes function fails to correctly escape single quote characters, leaving database queries vulnerable to manipulation. This occurs because the backslash character generated by the function does not effectively neutralize the single quote in the context of multibyte character processing, creating a pathway for attackers to inject malicious SQL code. The vulnerability specifically targets the addslashes function behavior when processing big5 character set data, where the escaping sequence becomes ineffective against single quote characters that are commonly used to terminate SQL string literals.
The operational impact of this vulnerability extends far beyond simple data corruption, as it provides attackers with the ability to execute arbitrary SQL commands on the underlying database system. This capability enables unauthorized users to perform a wide range of malicious activities including data extraction, modification, deletion, and potentially complete database compromise. Attackers can leverage this vulnerability to access sensitive user information, manipulate forum content, escalate privileges, or even establish persistent access to the system. The remote nature of the attack means that exploitation can occur from any location without requiring physical access to the server, making it particularly dangerous for publicly accessible forums. The vulnerability's exploitation requires minimal technical expertise, as demonstrated by the specific manlabels action example, making it a preferred target for automated attack tools.
This vulnerability aligns with CWE-89, which specifically addresses SQL injection flaws, and demonstrates the importance of proper input validation and character set handling in web applications. From an ATT&CK framework perspective, this vulnerability maps to T1190 - Exploit Public-Facing Application, as it represents an attack against a publicly accessible forum application. The flaw also connects to T1071.004 - Application Layer Protocol: DNS, through the potential use of DNS-based command and control mechanisms if the database compromise leads to further system access. Organizations should implement immediate mitigations including upgrading to SMF version 1.1.5 or later, which contains the necessary patches to address the character set handling issue. Additionally, implementing proper input validation, parameterized queries, and web application firewalls can provide additional layers of protection against similar vulnerabilities. The incident underscores the critical importance of thorough testing of character set handling in security-sensitive applications and the need for comprehensive security reviews of input processing functions.