CVE-2018-13065 in ModSecurity
Summary
by MITRE
ModSecurity 3.0.0 has XSS via an onerror attribute of an IMG element.
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Analysis
by VulDB Data Team • 08/05/2024
The vulnerability identified as CVE-2018-13065 represents a critical cross-site scripting flaw within ModSecurity version 3.0.0, specifically targeting the handling of onerror attributes within IMG elements. This issue arises from insufficient input validation and sanitization mechanisms within the web application firewall's rule processing engine, creating an avenue for malicious actors to execute arbitrary scripts in the context of a victim's browser session. The flaw demonstrates a fundamental weakness in the security module's ability to properly interpret and filter HTML content, particularly when processing image elements that contain event handlers.
The technical implementation of this vulnerability stems from ModSecurity's inadequate parsing of the onerror attribute within HTML IMG tags, which should normally be treated as a potential security risk due to its capability to execute JavaScript code when an image fails to load. The flaw occurs because the security rule engine fails to properly neutralize or validate the content of the onerror attribute, allowing attackers to inject malicious JavaScript payloads that can execute when the browser attempts to render the problematic image element. This represents a classic XSS vulnerability where the attack vector leverages HTML event handlers to bypass traditional security controls.
From an operational impact perspective, this vulnerability exposes organizations using ModSecurity 3.0.0 to significant risks including session hijacking, data exfiltration, and potential lateral movement within compromised networks. Attackers could craft malicious web pages containing specially crafted IMG tags with onerror attributes that would execute malicious scripts in the context of users' browsers, potentially stealing cookies, credentials, or other sensitive information. The vulnerability is particularly concerning because ModSecurity is widely deployed as a core web application firewall component, meaning that organizations relying on this version could have their entire web infrastructure exposed to these attacks. The impact extends beyond simple script execution as it undermines the fundamental security assurances that organizations expect from their WAF implementations.
Mitigation strategies for this vulnerability should prioritize immediate deployment of the patched version of ModSecurity 3.0.0, which includes proper sanitization of onerror attributes and enhanced HTML parsing routines. Organizations should implement additional layers of protection including Content Security Policy headers, input validation at multiple points in their application architecture, and regular security assessments of their WAF configurations. The vulnerability aligns with CWE-79 which specifically addresses cross-site scripting flaws, and represents a technique that could be categorized under ATT&CK tactic TA0001 (Initial Access) through the use of malicious web content. Security teams should also consider implementing web application firewalls with more robust HTML sanitization capabilities and establish monitoring procedures to detect unusual patterns in web traffic that might indicate exploitation attempts.