CVE-2015-9359 in Jetpack Plugin
Summary
by MITRE
The Jetpack plugin before 3.4.3 for WordPress has XSS via add_query_arg() and remove_query_arg().
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Analysis
by VulDB Data Team • 12/07/2023
The vulnerability identified as CVE-2015-9359 affects the Jetpack plugin for WordPress versions prior to 3.4.3, representing a cross-site scripting flaw that emerges from improper handling of URL query parameters. This issue specifically involves the add_query_arg() and remove_query_arg() functions within the plugin's codebase, which fail to adequately sanitize user-supplied input before incorporating it into dynamically generated URLs. The flaw exists in the plugin's core functionality that manages query string parameters for various administrative and user-facing features, creating an attack surface where malicious actors can inject malicious scripts into URLs that are subsequently processed by the WordPress platform.
The technical implementation of this vulnerability stems from the plugin's failure to properly escape or validate input data when manipulating query arguments in URL construction. When users interact with Jetpack features that utilize these functions, any unsanitized input becomes embedded directly into the URL structure without appropriate encoding or validation measures. This creates a scenario where an attacker can craft malicious URLs containing script tags or other harmful payloads that execute in the context of other users' browsers when they navigate to affected pages. The vulnerability manifests as a classic XSS attack vector because the plugin does not perform proper output encoding or input validation on the parameters passed through add_query_arg() and remove_query_arg() functions, allowing arbitrary code execution in the victim's browser context.
The operational impact of CVE-2015-9359 extends beyond simple script injection, as it can enable attackers to perform various malicious activities including session hijacking, credential theft, defacement of website content, and redirection to malicious sites. When exploited, this vulnerability allows unauthorized individuals to manipulate the behavior of legitimate users who visit affected WordPress sites, potentially compromising the entire website's security posture. The attack can be particularly devastating in environments where Jetpack is used for critical administrative functions or where users have elevated privileges, as the injected scripts could potentially escalate privileges or access sensitive administrative interfaces. The vulnerability affects not only individual users but also the broader WordPress ecosystem since Jetpack is one of the most widely used plugins, amplifying the potential scope of exploitation.
Mitigation strategies for this vulnerability require immediate patching of affected Jetpack installations to version 3.4.3 or later, which includes proper input validation and output encoding for the affected functions. System administrators should also implement additional security measures such as content security policies to limit the execution of unauthorized scripts, monitor for suspicious URL patterns in web server logs, and conduct regular security audits of installed plugins. The vulnerability aligns with CWE-79 which categorizes cross-site scripting flaws, and follows ATT&CK technique T1566 related to phishing attacks that leverage web-based exploits. Organizations should also consider implementing web application firewalls to detect and block malicious query parameter injection attempts, while maintaining up-to-date security monitoring to identify potential exploitation attempts. Regular security assessments of WordPress installations and plugin ecosystems remain critical for early detection and prevention of similar vulnerabilities in the future.