CVE-2016-9152 in SPIP
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in ecrire/exec/plonger.php in SPIP 3.1.3 allows remote attackers to inject arbitrary web script or HTML via the rac parameter.
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Analysis
by VulDB Data Team • 10/05/2022
The vulnerability identified as CVE-2016-9152 represents a critical cross-site scripting flaw within the SPIP content management system version 3.1.3. This vulnerability specifically affects the ecrire/exec/plonger.php script which serves as an execution handler for embedded content operations. The flaw arises from insufficient input validation and sanitization of user-supplied data, creating an exploitable entry point for malicious actors to inject arbitrary web scripts or HTML content into the application's response. The rac parameter, which appears to handle resource references or paths, becomes the primary vector for this attack, allowing remote threat actors to manipulate the application's behavior through crafted input sequences.
From a technical perspective, this vulnerability maps directly to CWE-79 which defines Cross-Site Scripting as a weakness where untrusted data is incorporated into web page content without proper validation or encoding. The flaw demonstrates a classic reflected XSS pattern where malicious input is immediately reflected back to users without adequate sanitization measures. The SPIP application fails to properly escape or validate the rac parameter before incorporating it into the generated HTML output, enabling attackers to execute arbitrary JavaScript code within the context of other users' browsers. This type of vulnerability can be particularly dangerous as it allows attackers to hijack user sessions, steal sensitive information, or perform unauthorized actions on behalf of authenticated users.
The operational impact of this vulnerability extends beyond simple data theft or display manipulation. Attackers can leverage this XSS flaw to establish persistent access patterns within the target environment, potentially leading to complete system compromise if the affected users have administrative privileges. The vulnerability affects the entire SPIP ecosystem as it resides in a core execution script that handles embedded content processing, making it a high-value target for exploitation. Organizations using SPIP 3.1.3 are particularly at risk since the vulnerability allows for the execution of malicious scripts that can redirect users to phishing sites, steal cookies, or inject malicious payloads that persist across user sessions. The remote nature of this attack means that threat actors can exploit the vulnerability without requiring physical access or prior authentication to the system.
Mitigation strategies for this vulnerability should focus on immediate patching of the SPIP application to version 3.1.4 or later where the XSS flaw has been addressed through proper input validation and output encoding. Additionally, implementing proper content security policies can help limit the damage from successful XSS attempts by restricting script execution within the application context. The recommended approach includes sanitizing all user inputs, particularly those passed through parameters like rac, and implementing proper HTML escaping mechanisms before rendering any dynamic content. Organizations should also consider deploying web application firewalls to detect and block suspicious input patterns targeting this specific vulnerability. Security monitoring should include detection of unusual parameter values in the plonger.php script and implementation of regular security audits to identify similar input validation weaknesses across the application codebase. The vulnerability serves as a reminder of the critical importance of input validation and output encoding practices in web application development, aligning with ATT&CK technique T1059.001 for command and scripting interpreter execution through XSS attacks.