CVE-2020-11083 in October
Summary
by MITRE
In October from version 1.0.319 and before version 1.0.466, a user with access to a markdown FormWidget that stores data persistently could create a stored XSS attack against themselves and any other users with access to the generated HTML from the field. This has been fixed in 1.0.466. For users of the RainLab.Blog plugin, this has also been fixed in 1.4.1.
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Analysis
by VulDB Data Team • 10/30/2020
This vulnerability represents a critical stored cross-site scripting flaw in the October CMS platform that affects versions prior to 1.0.466. The vulnerability specifically targets the FormWidget component which is commonly used for creating forms that store user data persistently. When a malicious user gains access to a markdown FormWidget, they can inject malicious javascript code into the form fields that gets stored in the database. This stored content is then rendered as HTML when other users access the form data, creating a persistent XSS attack vector that can compromise multiple users who have access to the affected system.
The technical implementation of this vulnerability leverages the insecure handling of markdown content within the FormWidget component. When markdown content is processed and stored, the system fails to properly sanitize or escape the input before rendering it as HTML. This creates a scenario where malicious javascript payloads can be embedded within markdown text and executed whenever the stored content is displayed. The vulnerability operates at the application layer and specifically targets the HTML rendering pipeline where user-supplied markdown content is converted to executable HTML. The flaw allows attackers to exploit the trust relationship between the application and its users, as the malicious code executes within the context of the victim's browser session.
The operational impact of this vulnerability is significant as it enables attackers to perform various malicious activities including session hijacking, credential theft, data exfiltration, and privilege escalation. Any user who has access to the affected FormWidget and can create or modify form content can potentially compromise not only their own session but also those of other users who view the stored data. This creates a multi-vector attack surface where the initial compromise can lead to broader system infiltration. The vulnerability is particularly dangerous in environments where multiple users have access to the same form data, as it allows for coordinated attacks across user sessions. The persistent nature of the stored XSS means that the attack remains active until the malicious content is removed from the database, making it difficult to detect and remediate.
The vulnerability is classified under CWE-79 as Cross-Site Scripting and aligns with ATT&CK technique T1566.001 for Initial Access through spearphishing attachments. The fix implemented in version 1.0.466 involves proper input sanitization and output encoding of markdown content to prevent javascript execution during HTML rendering. Security practitioners should implement comprehensive input validation, content security policies, and regular security assessments to prevent similar vulnerabilities in web applications. The patch specifically addresses the insecure direct object reference issue and ensures that user-generated content is properly escaped before being rendered to prevent XSS exploitation. Organizations using the RainLab.Blog plugin should also upgrade to version 1.4.1 to ensure complete protection against this vulnerability.