We found that the 301 redirect pages generated by some websites powered by Litespeed used to return hidden URLs as below. You can check websites powered by LiteSpeed at https://www.wappalyzer.com/technologies/litespeed
As you can see it looks like Litespeed injects an advertisement link to litespeedtech.com in the 301 redirect pages.
[[email protected] etc]# curl zhaket.com -I
HTTP/1.1 301 Moved Permanently
Date: Mon, 03 Sep 2018 09:31:29 GMT
Accept-Ranges: bytes
Server: LiteSpeed
Location: https://zhaket.com/
Connection: Keep-Alive
[[email protected] etc]# curl zhaket.com
<!DOCTYPE html>
<html style="height:100%">
<head><title> 301 Moved Permanently
</title></head>
<body style="color: #444; margin:0;font: normal 14px/20px Arial, Helvetica, sans-serif; height:100%; background-color: #fff;">
<div style="height:auto; min-height:100%; "> <div style="text-align: center; width:800px; margin-left: -400px; position:absolute; top: 30%; left:50%;">
<h1 style="margin:0; font-size:150px; line-height:150px; font-weight:bold;">301</h1>
<h2 style="margin-top:20px;font-size: 30px;">Moved Permanently
</h2>
<p>The document has been permanently moved.</p>
</div></div><div style="color:#f0f0f0; font-size:12px;margin:auto;padding:0px 30px 0px 30px;position:relative;clear:both;height:100px;margin-top:-101px;background-color:#474747;border-top: 1px solid rgba(0,0,0,0.15);box-shadow: 0 1px 0 rgba(255, 255, 255, 0.3) inset;">
<br>Proudly powered by <a style="color:#fff;" href="http://www.litespeedtech.com/error-page">LiteSpeed Web Server</a><p>Please be advised that LiteSpeed Technologies Inc. is not a web hosting company and, as such, has no control over content found on this site.</p></div></body></html>