Thread:Project:Support desk/Massive spam & vandalism. more than 150.000users!/reply (6)

You do not mean MW 1.9, but 1.19.

MW 1.19.4 should be secure currently. If you still get IPs spamming, although editing is disabled for IPs, then there obviously is a way to hack your wiki. I just had a look at your Special:Version page and it e.g. lists the extension "Maintenance Shell".

The version, which you use, has known security vulnerabilities. There are newer versions, in which several security issues have been fixed.

Apart from that, as the wiki page states, no matter if you use the newest version or not: This extension per se is a security risk. You should uninstall this extension.

If you continue having spam problems afterwards, see combating spam.