CVE-2009-5142 in timthumb
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in timthumb.php in TimThumb 1.09 and earlier, as used in Mimbo Pro 2.3.1 and other products, allows remote attackers to inject arbitrary web script or HTML via the src parameter.
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Analysis
by VulDB Data Team • 03/28/2019
The CVE-2009-5142 vulnerability represents a critical cross-site scripting flaw in the timthumb.php script version 1.09 and earlier, which was widely distributed in the WordPress ecosystem including the Mimbo Pro 2.3.1 theme. This vulnerability resides in the image handling functionality that processes external image sources through the src parameter, creating an avenue for malicious actors to inject arbitrary web scripts or HTML content into vulnerable applications. The flaw stems from inadequate input validation and sanitization within the timthumb.php script, which fails to properly escape or filter user-supplied parameters before incorporating them into dynamic web content. The vulnerability operates at the application layer and specifically targets web applications that utilize the timthumb library for image processing, making it particularly dangerous as it can affect numerous WordPress installations and other platforms that integrate this vulnerable component.
The technical exploitation of this vulnerability occurs when an attacker crafts a malicious URL containing script code within the src parameter of the timthumb.php script. When a victim visits a webpage that includes this maliciously crafted URL, the script executes within the victim's browser context, potentially leading to session hijacking, defacement, or the execution of malicious commands. The flaw is classified as a reflected XSS vulnerability according to CWE-79, which specifically addresses the improper handling of user-provided data in web applications. The vulnerability can be leveraged through various attack vectors including social engineering campaigns, compromised websites, or by exploiting the widespread use of vulnerable themes and plugins that incorporate the timthumb library. The impact extends beyond simple script injection as it can enable attackers to steal cookies, modify page content, redirect users to malicious sites, or perform actions on behalf of authenticated users.
The operational impact of CVE-2009-5142 is significant across multiple security domains and attack surfaces. Organizations utilizing vulnerable versions of timthumb are exposed to persistent threats that can compromise user sessions, steal sensitive information, and potentially allow full system compromise through privilege escalation attacks. The vulnerability's prevalence in popular WordPress themes means that a large number of websites were at risk, creating a substantial attack surface for threat actors. According to ATT&CK framework category T1566, this vulnerability represents a phishing technique that leverages web application flaws to deliver malicious payloads. The vulnerability also aligns with ATT&CK technique T1059 which involves the execution of malicious code through web-based attack vectors. Security professionals must consider that this vulnerability can be exploited as part of larger attack chains, potentially leading to complete system compromise when combined with other exploitation techniques.
Mitigation strategies for CVE-2009-5142 require immediate action to address the root cause through software updates and input validation improvements. Organizations should prioritize updating to timthumb version 1.10 or later, which includes proper input sanitization and validation mechanisms. Additionally, implementing proper parameter validation, output encoding, and content security policies can significantly reduce the attack surface. The use of web application firewalls and input filtering mechanisms can provide additional defense layers against exploitation attempts. Security measures should include regular vulnerability scanning, monitoring for suspicious URL patterns, and implementing proper access controls to limit the impact of potential exploitation. Organizations must also consider the broader context of their web application security posture, as this vulnerability demonstrates the importance of proper input validation and the dangers of incorporating third-party components without adequate security review. The remediation process should include comprehensive testing to ensure that updates do not break existing functionality while providing the necessary security protections against XSS attacks.