Websites hosted on a Plesk server with Imunify360 are intermittently unavailable: Error establishing a database connection

Symptoms

• Imunify360 packages have been recently upgraded on a Plesk server to 5.4.2-2 version:

  # grep imunify360 /var/log/yum.log
  Nov 25 03:46:51 Updated: imunify360-php-i360-rules-5.4.0-8.el7.x86_64
  Nov 25 03:47:56 Updated: imunify360-php-i360-5.4.0-1.12.el7.x86_64
  Nov 25 03:47:58 Updated: imunify360-pam-5.3.0-8.el7.x86_64
  Nov 25 03:48:00 Updated: imunify360-webshield-bundle-1.13-3.3.el7.x86_64
  Nov 25 03:48:01 Updated: imunify360-unified-access-logger-1.1.0-1.el7.x86_64
  Nov 25 03:48:01 Updated: imunify360-ossec-3.1.0-87.el7.x86_64
  Nov 25 03:48:02 Updated: imunify360-ossec-server-3.1.0-87.el7.x86_64
  Nov 25 03:48:04 Updated: imunify360-firewall-5.4.2-2.x86_64
  Nov 25 03:48:04 Updated: imunify360-firewall-plesk-5.4.2-2.noarch

• Sites periodically show:

  503 Service Temporarily Unavailable

• Below errors can be found in /var/log/messages

  # grep i360.so /var/log/messages
  Nov 25 03:47:45 optiwar-u kernel: php-fpm[25750]: segfault at 98 ip 00007f40804fd3e4 sp 00007fffd323a9c0 error 4 in i360.so[7f40804e9000+7e000]
  Nov 25 03:47:49 optiwar-u kernel: php-fpm[25751]: segfault at 98 ip 00007f40804fd3e4 sp 00007fffd323a9c0 error 4 in i360.so[7f40804e9000+7e000]

Cause

Immunify360 PHP extension bug, which has been fixed in version 5.4.3: https://blog.imunify360.com/imunify360-version-5.4.3-updated.

Resolution

Update the Immunify360 extension manually using the following commands:

# wget https://repo.imunify360.cloudlinux.com/defence360/imunify-force-update.sh
# bash imunify-force-update.sh

Alternatively, apply the following workaround:

1. Login to Plesk
2. Check what PHP version is used by site in Domains > example.com > PHP Settings
3. Disable i360 php extension for used php version in Tools & Settings > PHP Settings > X.X FPM application > Extensions