CVE-2012-4558 in HTTP Server
Summary
by MITRE
Multiple cross-site scripting (XSS) vulnerabilities in the balancer_handler function in the manager interface in mod_proxy_balancer.c in the mod_proxy_balancer module in the Apache HTTP Server 2.2.x before 2.2.24-dev and 2.4.x before 2.4.4 allow remote attackers to inject arbitrary web script or HTML via a crafted string.
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Analysis
by VulDB Data Team • 12/29/2021
The vulnerability identified as CVE-2012-4558 represents a critical cross-site scripting flaw within the Apache HTTP Server's mod_proxy_balancer module, specifically affecting the balancer_handler function in the manager interface. This issue impacts Apache versions prior to 2.2.24-dev and 2.4.4, creating a significant security risk for web applications that rely on load balancing functionality. The vulnerability stems from insufficient input validation and sanitization within the manager interface, which is designed to provide administrative control over proxy load balancer configurations. Attackers can exploit this weakness by crafting malicious strings that bypass the server's security controls, potentially executing arbitrary web scripts or HTML code within the context of authenticated user sessions.
The technical exploitation of this vulnerability occurs through the manipulation of input parameters within the balancer_handler function, which processes requests to the manager interface. When the server processes these malformed inputs without proper sanitization, the malicious content gets rendered in the browser of authenticated users who access the manager interface. This creates a persistent XSS vector that can be leveraged to steal session cookies, redirect users to malicious sites, or perform actions on behalf of authenticated users. The flaw is classified as CWE-79 - Improper Neutralization of Input During Web Page Generation, which specifically addresses the failure to properly escape or encode user-controllable data before including it in web page output. The vulnerability is particularly dangerous because it affects the manager interface, which typically requires administrative privileges, amplifying the potential impact of successful exploitation.
From an operational perspective, this vulnerability presents a severe risk to organizations using Apache HTTP Server with mod_proxy_balancer functionality, particularly those operating load-balanced web applications. The attack surface expands significantly when considering that the manager interface is often accessible to administrators and may be exposed to untrusted networks. Successful exploitation could lead to complete compromise of the load-balancing configuration, allowing attackers to redirect traffic to malicious servers, steal sensitive administrative credentials, or establish persistent backdoors within the web infrastructure. The vulnerability also poses risks to data integrity and availability, as attackers could manipulate the load-balancer configuration to disrupt service or create unauthorized access points. According to ATT&CK framework, this vulnerability maps to T1059.007 - Command and Scripting Interpreter: JavaScript and T1566.002 - Phishing: Spearphishing Attachments, as it enables the delivery of malicious JavaScript payloads and potential credential theft through compromised administrative sessions.
Organizations should immediately implement mitigations including upgrading to Apache HTTP Server versions 2.2.24-dev or 2.4.4, which contain the necessary patches to address this vulnerability. Additionally, implementing proper input validation and output encoding mechanisms in custom applications that interface with the manager functionality can provide additional defense-in-depth. Network segmentation and access controls should be enforced to limit exposure of the manager interface to trusted administrative networks only. Security monitoring should include detection of suspicious requests to the manager interface, particularly those containing unusual parameter patterns or attempts at script injection. Regular security assessments and penetration testing should be conducted to identify similar vulnerabilities in other components of the web infrastructure, as this vulnerability demonstrates the importance of validating all user inputs in administrative interfaces. The patching process should be prioritized at the highest level due to the potential for privilege escalation and the ease of exploitation through standard web-based attack vectors.