Advisory report: https://security.dxw.com/advisories/vulnerability-in-wp-ban-allows-visitors-to-bypass-the-ip-blacklist-in-some-configurations/
CVSS: 5 (Medium; AV:N/AC:L/Au:N/C:P/I:N/A:N)
Vulnerability in WP-Ban allows visitors to bypass the IP blacklist in some configurations
This plugin allows blacklisting users based on their IP address, however it takes the IP address from the X-Forwarded-For header if available.
Not all Web server configurations will strip or replace X-Forwarded-For headers in which case the IP ban can be bypassed by sending this header. This plugin therefore only works in certain configurations, but does not warn admins of this fact.
Proof of concept
Set “Banned IPs” to “127.0.0.1³
Execute “curl http://localhost/\" and see the “You Are Banned” message
Execute “curl http://localhost/ -H \'X-Forwarded-For: 999.999.999.999\'\" and see that it displays the page
Note that this will not work if your Web server sets or strips X-Forwarded-For headers.
(To remove the IP blacklist run this SQL: delete from wp_options where option_name=\'banned_ips\';\")
Upgrade to version 1.6.4 or later.
If a reverse-proxy is used, check the “I am using a reverse proxy” box in the plugin settings, and ensure that X-Forwarded-For headers are being set even if the request already contains an X-Forwarded-For header.
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This vulnerability will be published if we do not receive a response to this report with 14 days.
2014-09-04:Reported to vendor by email
2014-09-17:Vendorreported a fixed version released
Discovered by dxw:
Please visit security.dxw.com for more information.