Executive Summary

The Blog2Social: Social Media Auto Post & Scheduler plugin for WordPress has a vulnerability due to a missing capability check on the b2s_curation_draft AJAX action in all versions up to and including 8.7.4.

Specifically, the curationDraft() function only verifies if the user has the 'read' capability but does not check whether the user has permission to edit the target post.

Because the plugin grants UI access and nonce exposure to all user roles, authenticated attackers with Subscriber-level access or higher can exploit this flaw.

They can overwrite the title and content of arbitrary posts and pages by supplying a target post ID via the 'b2s-draft-id' parameter.

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Impact Analysis

This vulnerability allows authenticated users with low-level access (Subscriber and above) to modify the content of any post or page on the affected WordPress site.

An attacker could overwrite post titles and content arbitrarily, potentially defacing the website, injecting misleading or malicious content, or disrupting the site's normal operation.

Since the integrity of posts can be compromised without proper authorization, this can lead to loss of trust, damage to reputation, and possible further exploitation.

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Compliance Impact

I don't know

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Detection Guidance

[{'type': 'paragraph', 'content': "This vulnerability involves unauthorized modification of WordPress posts via the Blog2Social plugin's AJAX action 'b2s_curation_draft'. Detection involves monitoring for suspicious AJAX requests targeting this action, especially those that include the 'b2s-draft-id' parameter to overwrite post content."}, {'type': 'paragraph', 'content': "You can detect exploitation attempts by inspecting web server logs for POST requests to admin-ajax.php with the action parameter set to 'b2s_curation_draft'. Look for requests from authenticated users with Subscriber-level access or higher."}, {'type': 'paragraph', 'content': 'Suggested commands to detect such activity include:'}, {'type': 'list_item', 'content': 'Using grep to find suspicious AJAX calls in web server logs: grep "action=b2s_curation_draft" /var/log/apache2/access.log'}, {'type': 'list_item', 'content': 'Filtering for POST requests with \'b2s-draft-id\' parameter: grep "b2s-draft-id" /var/log/apache2/access.log'}, {'type': 'list_item', 'content': 'Using WordPress CLI to check recent post modifications that might be unauthorized: wp post list --post_type=post --orderby=modified --order=desc --fields=ID,post_title,post_modified'}, {'type': 'paragraph', 'content': 'Additionally, monitoring for unexpected changes in post titles and content, especially from users with low privileges, can help detect exploitation.'}] [3]

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Mitigation Strategies

Immediate mitigation steps include:

• Update the Blog2Social plugin to a version later than 8.7.4 where the missing capability check on the 'b2s_curation_draft' AJAX action is fixed.
• Restrict access to the plugin's AJAX actions by ensuring proper capability checks are enforced, especially verifying 'edit_post' permissions before allowing post modifications.
• Temporarily disable or restrict the plugin's AJAX endpoints if an immediate update is not possible.
• Review user roles and permissions to limit Subscriber-level users from having unnecessary access to plugin features.
• Monitor logs for suspicious activity related to the 'b2s_curation_draft' action and respond to any detected exploitation attempts.

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