Mass Assignment in K2 Joomla Plugin

Compliance Impact

The vulnerability allows a registered Joomla user to write arbitrary values into certain database columns (notes, image, plugins) of their own user record in the K2 extension. This could lead to unauthorized modification of user profile data that is not normally exposed via the frontend.

Such unauthorized data manipulation could potentially impact compliance with data protection regulations like GDPR or HIPAA, which require strict controls over personal data integrity and user consent. If malicious or incorrect data is injected into user profiles, it may lead to inaccurate or misleading personal information being stored or processed.

However, the provided information does not explicitly state the direct impact on compliance with these standards.

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Executive Summary

This vulnerability exists in K2 version 2.24 and earlier, specifically in the K2 system user plugin called plg_user_k2. It is a mass-assignment defect that allows a registered Joomla user to manipulate certain fields in their own user record.

By including the field K2UserForm=1 in a standard profile.save POST request to com_users, the user can write arbitrary values into the notes, image, and plugins columns of their own row in the #__k2_users database table. These fields are not normally exposed or editable through the K2 frontend profile-edit form.

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Impact Analysis

This vulnerability allows a registered user to modify hidden fields in their own user profile that are not normally accessible through the frontend interface.

Such unauthorized modifications could potentially be used to inject malicious data or alter user-related information in ways not intended by the application, which might lead to further exploitation depending on how these fields are used by the system.

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Detection Guidance

This vulnerability involves a mass-assignment defect in the K2 system user plugin plg_user_k2, where a registered Joomla user can modify certain fields in their own database row by including the field K2UserForm=1 in a com_users profile.save POST request.

To detect exploitation attempts on your system or network, you can monitor HTTP POST requests to the Joomla com_users profile.save endpoint that include the parameter K2UserForm=1.

Suggested commands to detect such activity include using network traffic inspection tools or web server logs analysis, for example:

• Using grep on web server access logs to find suspicious POST requests: grep -i 'profile.save' /path/to/access.log | grep 'K2UserForm=1'
• Using tcpdump or tshark to capture HTTP POST requests containing K2UserForm=1: tcpdump -A -s 0 'tcp port 80 and (((ip[2:2] - ((ip[0]&0xf)<<2)) - ((tcp[12]&0xf0)>>2)) != 0)' | grep 'K2UserForm=1'
• Using a web application firewall (WAF) or intrusion detection system (IDS) to create a rule that alerts on POST requests with the K2UserForm=1 parameter.

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Mitigation Strategies

Immediate mitigation steps include restricting or monitoring POST requests to the com_users profile.save endpoint that include the K2UserForm=1 parameter to prevent unauthorized modification of user data.

Additionally, consider applying any available patches or updates to the K2 extension that address this mass-assignment defect.

If patching is not immediately possible, you may temporarily disable the vulnerable K2 system user plugin plg_user_k2 or restrict access to it.

Implement monitoring and alerting on suspicious activity related to this vulnerability to detect exploitation attempts early.

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