CVE-2006-3758 in MyBB
Summary
by MITRE
inc/init.php in Archive Mode (Light) in MyBB (aka MyBulletinBoard) 1.1.4 calls the extract function with EXTR_OVERWRITE on HTTP POST and GET variables, which allows remote attackers to overwrite arbitrary variables, as demonstrated via an SQL injection using the _SERVER[HTTP_CLIENT_IP] parameter in archive/index.php.
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Analysis
by VulDB Data Team • 04/30/2019
The vulnerability described in CVE-2006-3758 represents a critical variable overwrite flaw within MyBB version 1.1.4's Archive Mode implementation. This issue resides in the inc/init.php file where the extract function is improperly configured with the EXTR_OVERWRITE flag, creating a dangerous attack surface that allows remote adversaries to manipulate core application variables. The vulnerability specifically manifests when processing HTTP POST and GET parameters through the archive/index.php endpoint, enabling attackers to inject malicious data that can override critical system variables.
The technical exploitation of this vulnerability leverages the PHP extract function's behavior when configured with EXTR_OVERWRITE, which allows variables from arrays to be imported into the current symbol table and potentially overwrite existing variables with the same names. In this case, attackers can manipulate the _SERVER[HTTP_CLIENT_IP] parameter to inject malicious values that overwrite critical application variables, ultimately enabling SQL injection attacks. This represents a classic variable overwrite vulnerability that falls under CWE-1287, which specifically addresses the improper handling of variable extraction in PHP applications. The flaw demonstrates a fundamental lack of input validation and proper variable scoping practices within the MyBB codebase.
The operational impact of this vulnerability is severe as it provides attackers with the ability to execute arbitrary SQL commands within the application's database context. By overwriting variables that control database queries or authentication mechanisms, attackers can potentially gain unauthorized access to sensitive user data, modify database records, or even escalate privileges within the system. This vulnerability directly aligns with ATT&CK technique T1190, which covers the exploitation of vulnerabilities in web applications to execute arbitrary code. The attack chain typically involves crafting malicious HTTP requests that leverage the variable overwrite to inject SQL payloads, potentially leading to full system compromise.
Mitigation strategies for this vulnerability require immediate implementation of proper input sanitization and variable handling practices. Developers should avoid using extract() with EXTR_OVERWRITE flags and instead implement explicit variable assignment or use safer alternatives such as extract() with EXTR_SKIP or EXTR_PREFIX_SAME flags. The recommended approach involves validating all incoming HTTP parameters against a whitelist of expected values and implementing proper escaping mechanisms for database queries. Additionally, system administrators should ensure that MyBB installations are updated to patched versions, as this vulnerability was addressed in subsequent releases. Network-level protections such as web application firewalls can provide temporary mitigation while patches are deployed, though the fundamental issue requires code-level remediation to ensure complete protection against similar variable overwrite attacks.