CVE-2017-8899 in IPS
Summary
by MITRE
Invision Power Services (IPS) Community Suite 4.1.19.2 and earlier has a composite of Stored XSS and Information Disclosure issues in the attachments feature found in User CP. This can be triggered by any Invision Power Board user and can be used to gain access to moderator/admin accounts. The primary cause is the ability to upload an SVG document with a crafted attribute such an onload; however, full path disclosure is required for exploitation.
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Analysis
by VulDB Data Team • 09/25/2020
The vulnerability identified as CVE-2017-8899 affects Invision Power Services (IPS) Community Suite versions 4.1.19.2 and earlier, specifically targeting the attachments feature within the User Control Panel. This security flaw represents a critical combination of stored cross-site scripting and information disclosure vulnerabilities that can be exploited by any registered user within the community platform. The vulnerability stems from insufficient input validation and sanitization mechanisms within the file upload processing system, creating a pathway for malicious actors to execute arbitrary code and potentially escalate privileges to administrative levels.
The technical exploitation of this vulnerability relies on the ability to upload specially crafted SVG (Scalable Vector Graphics) files that contain malicious attributes such as onload handlers. This particular attack vector is classified under CWE-79 as Cross-Site Scripting, while the information disclosure component falls under CWE-200 as Exposure of Sensitive Information. The SVG file upload functionality bypasses standard security checks because the system does not properly validate the content type or sanitize the SVG attributes before processing. The vulnerability requires a full path disclosure condition to be fully exploitable, which means attackers must first obtain directory traversal information to successfully execute the payload. This path disclosure typically occurs through error messages or other information leakage mechanisms within the application's response handling.
The operational impact of this vulnerability extends beyond simple XSS attacks as it provides a potential pathway for privilege escalation. An attacker who successfully uploads a malicious SVG file can execute scripts in the context of other users' browsers, potentially capturing session cookies or performing actions on behalf of victims. When combined with the information disclosure aspect, attackers can gain knowledge of system paths, user accounts, and potentially sensitive configuration details that can be leveraged for further exploitation. The attack surface is particularly concerning because it affects all users within the community suite, meaning any registered user can attempt to exploit this vulnerability without requiring special privileges or credentials.
The exploitation chain begins with an authenticated user uploading a crafted SVG file through the attachments feature, which is then stored on the server and served to other users. The onload attribute within the SVG file triggers JavaScript execution when the file is rendered in a browser, potentially allowing for session hijacking, data exfiltration, or redirection to malicious sites. The information disclosure component becomes critical when attackers can obtain file paths or system information through error responses, which then enables them to craft more sophisticated attacks or bypass additional security measures. This vulnerability aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter and T1068 for Exploitation for Privilege Escalation, demonstrating how a seemingly minor flaw in file handling can create significant security implications.
Mitigation strategies for CVE-2017-8899 should focus on implementing comprehensive input validation and sanitization for all file uploads, particularly SVG files which can contain executable code. Organizations should enforce strict content type checking, implement proper file extension validation, and sanitize all SVG attributes to prevent execution of potentially malicious code. The system should also disable or restrict SVG file processing capabilities where possible, as SVG files inherently pose a higher risk compared to traditional image formats. Additionally, implementing proper error handling and response management can prevent information disclosure that would otherwise aid attackers in their exploitation efforts. Regular security updates and patches from Invision Power Services should be applied immediately upon availability, as this vulnerability was addressed in later versions of the Community Suite. Network monitoring and intrusion detection systems should be configured to detect unusual file upload patterns or attempts to access potentially malicious content, providing an additional layer of defense against exploitation attempts.