CVE-2015-6829 in WP Limit Login Attempts Plugin
Summary
by MITRE
Multiple SQL injection vulnerabilities in the getip function in wp-limit-login-attempts.php in the WP Limit Login Attempts plugin before 2.0.1 for WordPress allow remote attackers to execute arbitrary SQL commands via the (1) X-Forwarded-For or (2) Client-IP HTTP header.
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Analysis
by VulDB Data Team • 06/15/2022
The CVE-2015-6829 vulnerability represents a critical SQL injection flaw in the WP Limit Login Attempts WordPress plugin, specifically affecting versions prior to 2.0.1. This vulnerability resides within the getip function in the wp-limit-login-attempts.php file, demonstrating a classic improper input validation issue that has been classified under CWE-89, which pertains to SQL injection vulnerabilities. The flaw manifests when the plugin processes HTTP headers, particularly the X-Forwarded-For and Client-IP headers, which are commonly used to determine client IP addresses in web applications that operate behind load balancers or proxy servers. These headers are often passed directly into SQL queries without proper sanitization or parameterization, creating an exploitable pathway for malicious actors to inject arbitrary SQL commands.
The technical exploitation of this vulnerability occurs through the manipulation of HTTP headers that the plugin uses to track login attempts and identify potential attackers. When an attacker crafts malicious payloads within the X-Forwarded-For or Client-IP headers, these values are directly incorporated into database queries without adequate input filtering or escaping mechanisms. This allows threat actors to execute unauthorized database operations, potentially leading to data exfiltration, data manipulation, or complete database compromise. The vulnerability aligns with ATT&CK technique T1190, which covers exploitation of remote services through injection flaws, and demonstrates how web application security controls can be bypassed when input validation is insufficient at critical points in the application logic. The attack vector is particularly concerning because it can be executed remotely without requiring authentication, making it an attractive target for automated exploitation tools and mass scanners.
The operational impact of CVE-2015-6829 extends beyond simple data theft, as successful exploitation can lead to complete system compromise and persistent backdoor access. Attackers can leverage the SQL injection to escalate privileges, modify user accounts, extract sensitive information from the WordPress database, or even inject malicious code into the application. The vulnerability affects WordPress installations that rely on the WP Limit Login Attempts plugin for security monitoring, creating a significant risk for websites that store user credentials, personal information, or business-critical data. Organizations using vulnerable versions face potential regulatory compliance violations, reputational damage, and financial losses from data breaches. The vulnerability also demonstrates how seemingly innocuous header processing can become a critical security weakness, highlighting the importance of validating all inputs regardless of their source or expected format.
Mitigation strategies for CVE-2015-6829 primarily focus on immediate patching of the WP Limit Login Attempts plugin to version 2.0.1 or later, which includes proper input sanitization and parameterization of database queries. System administrators should also implement network-level protections such as web application firewalls that can detect and block malicious header content patterns. Additional defensive measures include disabling unnecessary HTTP header processing in the plugin configuration, implementing strict input validation at multiple layers, and conducting regular security audits of third-party WordPress plugins. Organizations should also consider implementing database query logging and monitoring to detect suspicious SQL activity, which can serve as an early warning system for exploitation attempts. The vulnerability underscores the necessity of following secure coding practices such as those outlined in OWASP Top Ten and the principle of least privilege in database access, ensuring that applications validate and sanitize all inputs before processing them in any security-sensitive context.