Our WordPress website has been struggling for months from an ever-growing error_log file that consumes our disk house allocation. It is all SQL errors just like the one beneath, reporting a collation mismatch on a SQL question towards our WordPress database. The errors aren’t triggered by any regular operation on our website – they arrive in a burst each 1/2 hour, coinciding with a sequence of fast accesses from random worldwide IP addresses within the customer log. The queries include lengthy strings of mis-encoded characters, with some recognizable .com urls for spam web pages embedded. We subsequently suspect that that is seemingly all exterior origin from an automatic distributed spam attacker.
There are not any mismatched collations in our database tables. We have double-checked, and so they’re all utf8_general_ci. I am guessing that the collation mismatch error originates from the dangerous string within the question itself?
We will not deal with it by blocking the customer IP tackle due to the random distributed IP addresses used.
We have turned off all searches and varieties on our website, and put in plugins for Disable Search and Disable Running a blog. Modified SQL database password. The issue continues. Do not know the way the SQL question is being injected into our website.
We may flip off error logging, or simply preserve deleting the log each few days, however that does not actually repair the issue. Any recommendation appreciated.
Pattern error log entry:
[19-Oct-2021 16:14:55 UTC] WordPress database error Unlawful mixture of collations (utf8_general_ci,IMPLICIT) and (utf8mb4_unicode_520_ci,COERCIBLE) for operation '=' for question SELECT wp_redirection_items.*,wp_redirection_groups.place AS group_pos
FROM wp_redirection_items INNER JOIN wp_redirection_groups ON
wp_redirection_groups.id=wp_redirection_items.group_id AND wp_redirection_groups.standing='enabled'
AND wp_redirection_groups.module_id=1 WHERE (wp_redirection_items.regex=1
OR wp_redirection_items.url='/search/〔평창출장맛사지〕⇢24시출장샵→전주+모텔+가격◤（카톡:+hwp63）◦〔fкh846.сом〕출장코스가격⇛2019-03-27-09-40[]┼[][]w[]평창모텔+보도[]�%2') made by require('wp-blog-header.php'), require_once('wp-load.php'), require_once('wp-config.php'), require_once('wp-settings.php'), do_action('init'), WP_Hook->do_action, WP_Hook->apply_filters, call_user_func_array, WordPress_Module->init, Red_Item::get_for_url, Red_Item::get_old_url