Details
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Software: Content Audit
Version: 1.6
Homepage: http://wordpress.org/plugins/content-audit/
Advisory report: https://security.dxw.com/advisories/blind-sqli-vulnerability-in-content-audit-could-allow-a-privileged-attacker-to-exfiltrate-password-hashes/
CVE: CVE-2014-5389
CVSS: 3.6 (Low; AV:N/AC:H/Au:S/C:P/I:N/A:P)

Description
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Blind SQLi vulnerability in Content Audit could allow a privileged attacker to exfiltrate password hashes

Vulnerability
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An attacker with an admin account is able to add arbitrary text in the “Audited content types” option by using a DOM inspector to modify the value of a checkbox field. This text is then inserted into an SQL query and executed as part of a daily wp-cron job.
The fact that this is run only once a day makes it rather minor. An attacker would potentially need to poll /wp-cron.php repeatedly for 24 hours until they got the first result. As blind SQL injection attacks are usually done by comparing the first character to all possible characters – one at a time, until a match is found – it would take a very long time to exfiltrate useful data.
However, we don’t discount the possibility that someone cleverer than us could figure out a more practical attack.

Proof of concept
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Steps an attacker may take:

Visit /wp-admin/options-general.php?page=content-audit
Check an “Audited content types” checkbox
Right-click that checkbox and select “Inspect element”
Set the value attribute of the element to something which does sleep(5) if the first byte of the admin’s password hash is ‘a’ or sleep(10) otherwise
Press “Update Options”
Poll /wp-cron.php repeatedly until it takes longer than 5 seconds and record how long the request took
Repeat

Steps to take to verify that this issue exists:

Visit /wp-admin/options-general.php?page=content-audit
Check a “Audited content types” checkbox
Right-click that checkbox and select “Inspect element”
Set the value attribute of the element to “‘” (a single apostrophe)
Press “Update Options”
Add “add_action(‘init’, ‘content_audit_mark_outdated’);” to content-audit-schedule.php somewhere and load any page
This error should occur: “WordPress database error You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ‘2013-08-12′”
If you replace “$oldposts = $wpdb->get_results” with “echo” on line 134 of content-audit-schedule.php you’ll notice that it’s inserting the ‘ unescaped – which means that you can insert whatever you like


Mitigations
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You should update to version 1.62.

Disclosure policy
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dxw believes in responsible disclosure. Your attention is drawn to our disclosure policy: https://security.dxw.com/disclosure/

Please contact us on security@dxw.com to acknowledge this report if you received it via a third party (for example, plugins@wordpress.org) as they generally cannot communicate with us on your behalf.

This vulnerability will be published if we do not receive a response to this report with 14 days.

Timeline
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2014-08-11 – Discovered
2014-08-21 – Requested author email address via a contact form
2014-08-27 – Reported to author via email
2014-09-22 – No response from author; reminder sent
2014-09-23 – Author responded
2014-09-24 – Fix released
2014-10-01 – Published



Discovered by dxw:
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Tom Adams
Please visit security.dxw.com for more information.