CVE-2017-8898 in IPS
Summary
by MITRE
Invision Power Services (IPS) Community Suite 4.1.19.2 and earlier has stored XSS in the Announcements, allowing privilege escalation from an Invision Power Board moderator to an admin. An attack uses the announce_content parameter in an index.php?/modcp/announcements/&action=create request. This is related to the "<> Source" option.
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Analysis
by VulDB Data Team • 12/30/2019
The vulnerability CVE-2017-8898 represents a critical stored cross-site scripting flaw within Invision Power Services (IPS) Community Suite versions 4.1.19.2 and earlier, specifically affecting the announcements module functionality. This security defect allows malicious actors to escalate privileges from a standard moderator account to administrative level access, creating a severe escalation of privileges threat. The vulnerability manifests through the announce_content parameter within the index.php?/modcp/announcements/&action=create request handler, where user-supplied input is inadequately sanitized before being stored and subsequently rendered to other users. The flaw is particularly concerning because it leverages the "<> Source" option functionality, which typically provides a rich text editing interface that should properly escape or encode user input to prevent malicious script execution. This stored XSS vulnerability enables attackers to inject malicious JavaScript code that executes whenever legitimate users view the announcements, potentially compromising user sessions and enabling further exploitation.
The technical implementation of this vulnerability stems from insufficient input validation and output encoding within the IPS Community Suite's announcement creation process. When moderators create announcements using the affected interface, the system fails to properly sanitize the announce_content parameter before storing it in the database. The "<> Source" option, which allows users to toggle between rich text and source code modes, does not adequately escape or filter content when transitioning from source mode back to rendered content. This creates a persistent XSS vector where malicious scripts can be stored in the database and executed whenever the announcement is displayed to other users. The vulnerability's impact is amplified by the fact that it operates at the privilege escalation level, allowing a low-privileged user to gain administrative capabilities, which directly violates the principle of least privilege and could lead to complete system compromise. According to CWE standards, this represents a CWE-79: Cross-site Scripting vulnerability, specifically classified as a stored XSS variant that enables privilege escalation through user input manipulation.
The operational impact of CVE-2017-8898 extends beyond simple script execution, as it creates a persistent backdoor for attackers to maintain access to compromised systems while potentially exfiltrating sensitive data or modifying system configurations. Once an attacker successfully exploits this vulnerability, they can execute JavaScript code that may steal session cookies, redirect users to malicious sites, or perform actions on behalf of legitimate users. The privilege escalation aspect means that moderators who create malicious announcements can effectively become administrators, gaining access to system management functions, user data, and potentially sensitive configuration information. This vulnerability aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter, specifically JavaScript execution, and T1078.002 for Valid Accounts through the exploitation of administrative privileges. The stored nature of this XSS means that the attack persists even after the initial injection, making detection and remediation more challenging.
Mitigation strategies for CVE-2017-8898 require immediate implementation of multiple defensive measures to protect affected systems. Organizations should upgrade to IPS Community Suite version 4.1.19.3 or later, which contains the necessary patches addressing the input sanitization issues. Immediate input validation should be implemented at the application level, ensuring all user-supplied content passed through the announce_content parameter undergoes proper HTML sanitization and encoding before storage. The "<> Source" functionality should be modified to properly escape or filter content regardless of the mode selected, preventing malicious scripts from being stored in the database. Security headers including Content-Security-Policy should be implemented to limit script execution capabilities, and regular security auditing of user input handling functions should be conducted. Additionally, implementing proper access controls and monitoring for unusual administrative activities can help detect exploitation attempts. According to industry best practices, this vulnerability demonstrates the importance of the OWASP Top 10 security controls, particularly focusing on input validation and output encoding, as well as the principle of defense in depth through multiple security layers to protect against similar vulnerabilities in the future.