CVE-2018-10297 in DiscuzX
Summary
by MITRE
Discuz! DiscuzX through X3.4 has stored XSS via the portal.php?mod=portalcp&ac=article URI, related to mishandling of IMG elements associated with remote images.
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Analysis
by VulDB Data Team • 01/30/2020
The vulnerability identified as CVE-2018-10297 affects Discuz! DiscuzX versions through X3.4 and represents a stored cross-site scripting flaw that manifests through the portal.php?mod=portalcp&ac=article URI. This issue arises from improper handling of IMG elements when processing remote images within the portal content management system. The vulnerability enables attackers to inject malicious scripts into stored content that will execute in the context of other users who view the affected pages.
The technical flaw stems from inadequate input validation and sanitization of image source attributes when users create or edit articles through the portal content management interface. When administrators or users submit content containing remote image references, the system fails to properly sanitize the img tag attributes, particularly the src attribute that points to external image resources. This weakness allows attackers to embed malicious JavaScript code within image URLs or image attributes, which gets stored in the database and subsequently executed when other users browse the affected portal pages.
The operational impact of this vulnerability extends beyond simple script execution as it enables attackers to perform various malicious activities including session hijacking, credential theft, and unauthorized actions within the Discuz! forum environment. Attackers can craft malicious image URLs that contain javascript: protocols or data: URIs that execute arbitrary code in the victim's browser context. This stored nature of the vulnerability means that once the malicious content is injected and saved, it persists and affects all users who view the compromised pages without requiring additional user interaction beyond visiting the affected portal sections.
The vulnerability aligns with CWE-79 Cross-site Scripting and follows patterns consistent with CWE-116 Improper Encoding or Escaping of Output, where the system fails to properly escape or validate user-supplied data before rendering it in web pages. From an attack framework perspective, this vulnerability maps to ATT&CK technique T1566.001 Phishing via Social Engineering, as attackers can craft malicious content that appears legitimate but executes harmful scripts when viewed by unsuspecting users. The attack chain typically involves an attacker gaining access to a portal management account or exploiting a vulnerability in the content creation process to inject malicious code that then executes for all users viewing the affected pages.
Mitigation strategies for this vulnerability include implementing comprehensive input validation and output encoding for all user-supplied content, particularly image attributes and URLs. Administrators should ensure that all image source attributes are properly validated against a whitelist of trusted domains or implement strict URL validation that prevents javascript: and data: protocols from being used in image sources. The system should also implement proper HTML sanitization routines that remove or escape potentially dangerous attributes from img tags. Regular security updates and patches should be applied immediately upon availability, and access controls should be strengthened to limit who can create or edit portal content, reducing the attack surface for potential exploitation.